2023 |
Adams, A., Daval, D., Baumgartner, L. P., Bernard, S., Vennemann, T., Cisneros-Lazaro, D., et al. (2023). Rapid grain boundary diffusion in foraminifera tests biases paleotemperature records. Communications Earth & Environment, 4(1).
Résumé: The paleoseawater temperature record from the oxygen isotope compositions of fossil foraminifera tests may be biased by up to about 1 degrees C due to grain-boundary diffusion alone, according to isotope exchange experiments on foraminifera tests. The oxygen isotopic compositions of fossil foraminifera tests constitute a continuous proxy record of deep-ocean and sea-surface temperatures spanning the last 120 million years. Here, by incubating foraminifera tests in O-18-enriched artificial seawater analogues, we demonstrate that the oxygen isotopic composition of optically translucent, i.e., glassy, fossil foraminifera calcite tests can be measurably altered at low temperatures through rapid oxygen grain-boundary diffusion without any visible ultrastructural changes. Oxygen grain boundary diffusion occurs sufficiently fast in foraminifera tests that, under normal upper oceanic sediment conditions, their grain boundaries will be in oxygen isotopic equilibrium with the surrounding pore fluids on a time scale of <100 years, resulting in a notable but correctable bias of the paleotemperature record. When applied to paleotemperatures from 38,400 foraminifera tests used in paleoclimate reconstructions, grain boundary diffusion can be shown to bias prior paleotemperature estimates by as much as +0.86 to -0.46 degrees C. The process is general and grain boundary diffusion corrections can be applied to other polycrystalline biocarbonates composed of small nanocrystallites (<100 nm), such as those produced by corals, brachiopods, belemnites, and molluscs, the fossils of which are all highly susceptible to the effects of grain boundary diffusion.
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Aguilar, G., Martinod, J., Gallardo, M., & Sue, C. (2023). Chronology of the Bayo River valley deglaciation and implications for the Late Pleistocene Atlantic-to-Pacific drainage reversal of the General Carrera-Buenos Aires palaeolake, Patagonia-Chile. Andean Geology, 50(1), 1–21.
Résumé: We present a study on the glacial and paraglacial geomorphology of a Patagonian Cordillera Valley that is key to understanding evolution of the great lakes of Patagonia. 10Be cosmogenic nuclide exposure ages of ice-moulded surfaces from the Bayo River Valley confirm that the valley became ice-free before 13.4-14.2 ka. This valley constituted the first outlet of the Chelenko Lake, precursor of the General Carrera-Buenos Aires Lake (GCBAL), toward the Pacific Ocean. This age constrains the timing of the lake drainage reversal from the Atlantic Ocean to the Pacific Ocean. Alluvial fans and terrace levels recognized in the eastern segment of the valley at the same altitude as terrace levels observed in the GCBAL basin confirm that the Bayo Pass controlled the elevation of the lake once the drainage reversed to Pacific Ocean. 10Be cosmogenic nuclide exposure ages also confirm that the maximum advance of the Exploradores Glacier since its major retreat >13.4-14.2 ka ago occurred during the Little Ice Age, the last remnant of glacial drift in these valleys.
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Aichele, J., Latour, S., Catheline, S., & Roux, P. (2023). Dynamic Full-Field Imaging of Rupture Radiation: Material Contrast Governs Source Mechanism. Geophysical Research Letters, 50(1).
Résumé: In seismology, the rupture mechanisms of an earthquake, a glacier stick-slip and a landslide are not directly observed, but inferred from surface measurements. In contrast, laboratory experiments can illuminate near field effects. The near field reflects the rupture mechanism but is highly attenuated in the case of real-world surface data. We directly image the elastic wave-field of a nucleating rupture non-invasively in its near-field with ultrasound speckle correlation. Our imaging yields the particle velocity of the full shear wave field at the source location and inside the 3D frictional body. We experimentally show that a strong bimaterial contrast, as encountered in environmental seismology, yields a unidirectional or linear force mechanism for pre-rupture microslips and decelerating supershear ruptures. A weak contrast, characteristic for earthquakes, generates a double-couple source mechanism for sub-Rayleigh ruptures, sometimes preceded by slow deformation at the interface. This deformation is reproduced by the NF of a unidirectional force.
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Aminov, J., Roperch, P., Dupont-Nivet, G., Cordier, C., Guillot, S., Glodny, J., et al. (2023). Contractional deformation between extensional dome exhumation in Central Pamir at 17-15 Ma constrained by metamorphic and paleomagnetic data from the Bartang volcanic rocks, Tajikistan. Tectonophysics, 868.
Résumé: The debated mechanism and timing of formation of the Pamir orogenic salient provides an ideal case to combine paleomagnetic and metamorphic analyses. Opposing views argue for either oroclinal bending of the Pamir since the India-Asia collision or for an originally arcuate shape, which can be tested using paleomagnetism to estimate vertical-axis rotations. Furthermore, Pamir deformation can be dated and characterized by the analysis of a well-expressed regional metamorphism. However, paleomagnetism is seldom applied to metamorphic rocks such that the significance of their rock magnetic signal with respect to deformation remains poorly understood. We studied a > 2 km thick sequence of slightly metamorphosed Cretaceous-Paleogene volcanic and volcaniclastic rocks from the western Central Pamir Mountains using metamorphic petrology, geochronology, and paleomagnetic analyses. These rocks present a medium-grade metamorphism and have undergone fine grained recrystallisation of biotite due to NW-SE compression. 40Ar/39Ar and Rb/Sr ages (similar to 17 to 15 Ma) on whole rock and biotite, confirm that the greenschist facies metamorphism is related to the coeval exhumation of Pamir gneiss domes during the Middle Miocene. The rocks generally show homogenous magnetic properties. High field magnetic properties and SEM/EDS data show that the main magnetic remanent carrier is titano-hematite. Thermal demagnetizations yield complex characteristic remanent magnetization with site-mean directions obtained for only 14 of the 44 studied sites but scattered mainly within the foliation plane defined by the anisotropy of magnetic susceptibility (AMS). These rocks have also unusual magnetic characteristics where strong-field isothermal remanent magnetizations induce an AMS fabric, likely related to the specific composition and structure of the metamorphic titano-hematite but independent of the original anisotropy fabrics. Combined paleomagnetic and geochronological data from the Bartang volcaniclastics rocks enable us to identify a similar to 17-15 Ma compressive deformation event contemporaneous with the emplacement of the gneiss domes and suggest no oroclinal bending since that event.
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Andrieu, B., Marrauld, L., Vidal, O., Egnell, M., Boyer, L., & Fond, G. (2023). Health-care systems' resource footprints and their access and quality in 49 regions between 1995 and 2015:an input-output analysis. Lancet Planetary Health, 7(9), E747–E758.
Résumé: Background Strategies to reduce the environmental impact of health care are often limited to greenhouse gas emissions. To broaden their scope, our aim was to determine the evolution of the resource footprints, dependency, and efficiency of health-care systems and to determine the relationship between this evolution and their Healthcare Access and Quality (HAQ) index.Methods We carried out an input-output analysis of 49 health-care systems from 1995 to 2015. We harmonised the EXIOBASE v3.8.2 database-providing data for 49 world regions-to the World Health Organization Health Expenditures Database. We then performed a panel data analysis to understand the relationship between Healthcare Access and Quality index and energy footprint per capita of health-care systems. EXIOBASE3 does not provide measurement errors so it was not possible to propagate the uncertainties as can be done with other input-output databases.Findings Health-care systems' footprint increased over the past two decades, reaching 7% of global non-metallic minerals footprint, 4% of global metal ores footprint, and 5% of global fossil fuels footprint in 2013. This increase was mostly due to China, rising from 7% of the non-metallic minerals footprint in 1995 to 45% in 2013. 80% of the health-care systems studied were dependent at more than 50% on fossil fuel imports. The energy footprint per capita was correlated exponentially with the HAQ index but some countries performed much better than others at a given energy footprint. Health-care systems have not become more efficient between 2002 and 2015.Interpretation Health-care systems' resources footprint are exponentially linked to their HAQ. Both prevention and efficiency measures will be needed to change this relationship. If it is not enough, high-income countries will have to choose between further reducing the resource consumption of their health-care systems or shifting the efforts to other sectors, health being considered an incompressible need. We call for the creation of a HAQE (health-care access, quality, and efficiency) index that would add resource efficiency to access and quality when ranking health-care systems.Funding The Shift Project.Copyright (c) The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND IGO license.
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Andrieu, B., Roche, M., Simeone, P., Leone, M., Marie, B. D. S., Andre, B., et al. (2023). Navigating Healthcare's Dual Fronts – Balancing Quality and the Environment. Revue D Epidemiologie Et De Sante Publique, 71(6).
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Annen, C., Pinel, V., & Burgisser, A. (2023). <i>Re</i>-evaluation of the role of volatiles in the rupture of magma chambers and the triggering of crystal-rich eruptions. Journal Of Volcanology And Geothermal Research, 435.
Résumé: The role of volatile exsolution in triggering volcanic eruption is re-evaluated using numerical simulations of a growing and solidifying magma chamber. The modelled magma chamber is silicic, emplaced at about 2 Kbar, and H2O-saturated. The rate of volume additions to the chamber by the release of volatiles is controlled by cooling and solidification and is significantly lower than magma infilling rates. Thus, the increase in volume due to volatile exsolution is unlikely to be the primary cause of magma chamber failure unless the magma chamber is already on the brink of failure. However, the formation of buoyant H2O rich layers within the mush that sur-rounds the magma chamber makes the system gravitationally unstable. If the host rock is not permeable and volatiles accumulate, their buoyancy might overcome the strength of the wall resulting in dyke injection and possibly an eruption. Eruptions that are triggered or facilitated by volatiles exsolution are associated to the presence of mush in the chamber and are expected to be crystal-rich. Triggering of eruption by volatiles buoyancy explains the common occurrence of large ranges of crystals ages and protracted crystal residence times at low temperature.
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Arguello, D., Chavez, E., Gutierrez, E., Pittomvils, M., Dekeyrel, J., Blommaert, H., et al. (2023). Soil amendments to reduce cadmium in cacao<i> (Theobroma</i><i> cacao</i> L.): A comprehensive field study in Ecuador. Chemosphere, 324.
Résumé: The new EU regulations on maximum levels of cadmium (Cd) in cacao products sparked research on counter-measures to reduce Cd concentrations in cacao beans. This study was set up to test the effects of soil amendments in two established cacao orchards (soil pH 6.6 and 5.1) in Ecuador. Soil amendments included: 1) agricultural limestone at 2.0 and 4.0 Mg ha-1 y-1, 2) gypsum at 2.0 and 4.0 Mg ha-1 y-1 and 3) compost at 12.5 and 25 Mg ha-1 y-1, all amendments were applied at the surface during two subsequent years. Lime application increased the soil pH by one unit down to 20 cm depth. On the acid soil, leaf Cd concentrations decreased by lime application and the reduction factor gradually rose to 1.5 after 30 months. No effects of liming or gypsum on leaf Cd was found in the pH neutral soil. Compost application in the pH neutral soil reduced leaf Cd concentration with factor 1.2 at 22 months but that effect was absent at 30 months after application. Bean Cd concentrations were unaffected by any of the treatments at 22 months after application (acid soil) or 30 months (pH neutral soil) suggesting that any treatment effects on bean Cd might be even more delayed than in leaves. Soil columns ex-periments in the laboratory showed that mixing lime with compost largely enhanced the depth of lime pene-tration compared to lime only. Compost + lime reduced 10-3 M CaCl2 extractable Cd in soil without lowering extractable Zn. Our results suggest that soil liming has the potential to lower Cd uptake in cacao in the long term in acid soils and that the compost + lime treatment should be tested at field scale to accelerate the effects of the mitigation.
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Arndt, N., Ganino, C., & Li, C. (2023). Comment on: Baddeleyite U-Pb age and Hf isotopes, and constraints on genesis of the Panzhihua carbonatite in SW China by Wang et al. (2023). Ore Geology Reviews, 159.
Résumé: Wang et al. (2023) propose that rocks adjacent to the Panzhihua intrusion are not marbles and skarns, but carbonatites. If true, this interpretation could have important implications for models explaining the origin of the large Fe-Ti ore deposits in the intrusion. We reject this interpretation for two principal reasons: 1) the objects described as “mantle xenoliths”, and considered, incorrectly, as diagnostic of carbonatite, are in fact deformed and altered mafic/ultramafic intrusions; 2) the concentrations of incompatible trace elements in the marbles are low and typical of metasedimentary rocks, not carbonatite.
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Arrospide, C., Aguilar, G., Martinod, J., Rodriguez, M. P., & Regard, V. (2023). Coastal cliff evolution: Modelling the long-term interplay between marine erosion, initial topography, and uplift in an arid environment. Geomorphology, 428.
Résumé: Coastal cliff evolution is modulated by several factors, such as uplift, marine erosion, previous topographical conditions, and changes in global sea level. In this study, a numerical model is used to understand the influence of these processes on the evolution of coastal cliffs. This model is based on erosional and tectonic conditions of the Great Coastal Cliff in the Atacama Desert, the tallest and most uninterrupted coastal cliff on Earth. The results show that a faster uplift rate (> 0.3 mm/yr) or an older onset of uplift (3 Myrs) favors the formation of inactive cliffs, whereas active cliffs preferentially form under conditions of a slow uplift (0.2 mm/yr) or a younger uplift onset (1 Myr). Low erosion rates (< 1 m2/yr) also favor the preservation of sequences of staircase marine ter-races, separating the seashore from an inactive coastal cliff. In contrast, high erosion rates (>= 1 m2/yr) inhibit marine terrace formation, keeping the cliff active. The effect of erosion on cliff activity is enhanced or reduced by the slope of the initial topography. Steep coasts (> 5-10 degrees) may hamper cliffs from reaching an inactive state. Thus, this model gives insights on the relative importance of these variables on the development of active and inactive cliffs, especially in an environment such as the Atacama Desert in northern Chile.
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Aslan, G., de Michele, M., Raucoules, D., Renard, F., Dehls, J., Penna, I., et al. (2023). Dynamics of a giant slow landslide complex along the coast of the Aral Sea, Central Asia. Turkish Journal Of Earth Sciences, 32(6), 819–832.
Résumé: We report here a slow-moving landslide complex of the lateral spreading type revealed by Sentinel-1 interferometric time-series analysis. Located along the western coast of the Aral Sea, with a >150-km length and 3-km width, a giant active landslide complex, slides with a constant velocity of up to 60 mm/year. Systematic subsidence up to 5 mm/year is also observed along narrow strips of terraces that appear to result from rotations of fault-bounded blocks. The landslide deformation velocity does not correlate with the annual variations of the water level in the southwestern lake of the Aral Sea during the observation period of 2014-2022, indicating a long-term forcing of this landslide that is rather interpreted to be caused by the long-term sea-level drop. The lateral spreading involves the competent limestone beds lying horizontally on plastic clay-and evaporite-rich layers. We propose a conceptual model for the kinematic of landslides that appear to be controlled by the attitude of bedding, lithological sequence, hydrogeology, and low angle faults.
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Aucour, A. M., Sarret, G., Blommaert, H., & Wiggenhauser, M. (2023). Coupling metal stable isotope compositions and X-ray absorption spectroscopy to study metal pathways in soil-plant systems: a mini review. Metallomics, 15(4).
Résumé: Excess and limited trace metal contents in soils and plants can limit crop yields and pose a risk for the environment and human health. This mini-review reports on the emerging approach of combining X-ray absorption spectroscopy (XAS) with isotope analyses to improve the understanding of metal speciation and dynamics in soil-plant systems. In soils and their components, shifts in isotope compositions could be in some cases linked to changing metal speciation and thereby provide information on processes that control the phytoavailability of metals. In plants, the XAS-isotope approach has potential to improve the understanding of how complex interactions of metal speciation, redox processes, and membrane transport control metal uptake and translocation to edible plant parts. Yet, the XAS-isotope approach proves to be in a rather exploratory phase, and many research gaps remain. Such limitations can be overcome by methodological improvements and combining the approach with molecular biology and modelling approaches.
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Audin, L., Gerard, B., Gautheron, C., Schwartz, S., Benavente, C., Robert, X., et al. (2023). Burial in the western Central Andes through Oligocene to Miocene ignimbrite flare-ups recorded by low-temperature thermochronology in the Canete Canyon, Peru. Terra Nova, 35(6), 488–497.
Résumé: Thermochronological data are essential to constrain thermal and exhumation histories in active mountain ranges. In the Central Andes, bedrock outcrops are rare, being blanketed by widespread late Palaeogene-Neogene and younger volcanic formations. For this reason, the exhumation history of the Western Cordillera (WC) in the Peruvian Andes has only been investigated locally along the mountain range. Dense thermochronological data are only available in canyons of the Arequipa (16 degrees S) and Cordillera Negra regions (10 degrees S). We present new apatite (U-Th)/He and fission-track data from the 1 km deep Canete Canyon (13 degrees S), where the Oligo-Miocene deposits are preserved lying conformably on an Eocene palaeo-topographic surface. Thermal modelling of thermochronological data indicate that the 30-20 Ma ignimbrite deposits overlying the bedrock were thick enough to cause burial reheating. We demonstrate that burial associated with thick volcanic formations should be taken into account when interpreting thermochronological data from the WC or in similar volcanic-arc settings.
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Authemayou, C., Nunez, A., Pedoja, K., Penalver, L., Chauveau, D., Dunan-Avila, P., et al. (2023). Oblique Collision of the Bahamas Platform at the Northern Boundary of the Caribbean Plate Recorded by the Late Cenozoic Coastal Terraces of SE Cuba. Tectonics, 42(8).
Résumé: The southeastern tip of Cuba Island is limited to the south by the N-Caribbean boundary. By revisiting the impressive sequences of coastal terraces of this region, we decipher the Quaternary deformation pattern of this plate boundary. We present a detailed mapping of coastal terraces uplifted over a hundred kilometers of coastline, and U/Th dating. At Punta de Maisi, the deformation pattern shows (a) a faster uplift close to the transform boundary and (b) a northward propagation of folding produced by the convergence of the Bahamas platform toward the Caribbean plate. Along the southern coast of Punta de Maisi, the sequence displays 29 coastal terraces up to 520 m in elevation and a upper Pleistocene uplift rate of 0.23 +/- 0.07 mm yr(-1). We interpret this deformation as resulting from an offshore north-dipping reverse fault near the coast. This uplift rate corresponds to 3% to 1.6% of the short-term horizontal slip rate of Septentrional Oriente Fault Zone (10 +/- 0.1 mm yr(-1)). Along the northern coast of Punta de Maisi, the sequence displays height coastal terraces up to 220 m in elevation and the uplift rates amount to 0.1 +/- 0.05 mm yr(-1) and likely result from the reverse faulting and folding associated with the offshore North Hispaniola Fault Zone. Uplift rates quickly decrease to the West, in agreement with the westward decrease in the activity of the North Hispaniola Fault Zone due to the docking of the Bahamas Platform against Cuba, while the platform more gently underthrusts Cuba to the East.
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Badreldin, H., Abu El-Ata, A., El-Hadidy, M., Cornou, C., Abd el-aal, A. el-aziz K., & Lala, A. M. (2023). Active and passive seismic methods for site characterization in Nuweiba, Gulf of Aqaba, Egypt. Soil Dynamics And Earthquake Engineering, 172.
Résumé: Nuweiba is located on the western coast of the Gulf of Aqaba (GoA), which represents the southern part of the Gulf of Aqaba – Dead Sea transform fault (GoA-DST). The GoA is characterized by high seismic activity and is the source of the November 22, 1995, Nuweiba earthquake, with a moment magnitude of Mw 7.3. This seismic unrest caused extensive damage in the city of Nuweiba due to the strong shaking caused by the earthquake. In addition, soil amplification triggered by the thick soft-sediments of the Wadi Watir delta beneath the city amplified the destructive power of the event. Therefore, an assessment of the effect of the Wadi Watir sediments on the ground motion at Nuweiba is very important for future construction, seismic hazard assessment, and seismic risk mitigation. Accordingly, the goal of the current study is to define the amplification characteristics of the Wadi Watir deposits using microtremor and surface wave data sets. The horizontal-to-vertical spectral ratio (HVSR) technique is applied to the microtremor data and Multichannel Analysis of Surface Waves (MASW) is applied to the surface wave data. The data are processed to obtain the distribution of the fundamental resonance frequency (F0), the depth of the geophysical bedrock using joint inversion of the Rayleigh wave dispersion curve and ellipticity peak, the shear wave velocity structure, the time-averaged shear-wave velocity in the topmost 30 m (Vs30), and the shear wave transfer function. The results of the HVSR show that F0 in the northern part of the city is 4.2-5.2 Hz and 0.5-0.8 Hz in the middle of the city. Bedrock depth is found to be in the range of 27 and 199 m. The one-dimensional velocity structure obtained from the MASW measurements has resolved two sedimentary layers within the upper 15 m. The Vs30 ranges between 207 and 556 m/s, according to the Vs30 the soil in the study area is categorized into soil classes B and C according to Eurocode 8. The obtained shear wave transfer functions show that the highest amplification factors are observed in the middle part of the study area.
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Bahamonde, H. A., Pimentel, C., Lara, L. A., Bahamonde-Fernandez, V., & Fernandez, V. (2023). Foliar Application of Potassium Salts to Olive, with Focus on Accompanying Anions. Plants-Basel, 12(3).
Résumé: Potassium (K) is an essential element, which is often supplied to horticultural crops via foliar spraying. Some studies have investigated the effect of different foliar-applied K compounds; however, most studies have focussed on crop quality and yield parameters, or were performed with isolated leaf cuticles. The aim of this study was to evaluate the rates of the foliar ion penetration and leaf surface deposition of 130 mM K sprays of compounds with markedly different point of deliquescence (POD) and efflorescence (POE) values, the rates having been previously estimated in climate chamber trials. Shoots of field-grown, commercial olive trees were sprayed with K-nitrate (KNO3), K-sulphate (K2SO4), K-chloride (KCl), K-phosphate (K3PO4), K-carbonate (K2CO3) and K-bicarbonate (KHCO3), and leaf samples were collected after 3 and 24 h. Cation and anion concentrations were determined in the leaf tissues, and in a preliminary leaf water wash for estimating surface-deposited ion concentrations. No significant leaf tissue K increments were recorded between the K sprays. Olive tissue anion concentrations showed different patterns, and a chloride (Cl-) increase was detected 3 h after the foliar KCl supply. On the other hand, the foliar K applications led to leaf nitrate changes regardless of the K source supplied. High amounts of K and accompanying ions were recovered in the washing liquid of the foliar K-supplied leaves. Some foliar K treatments increased the leaf surface concentration of sulphate and chloride, suggesting a potential effect on leaf cell anion extrusion. Hence, despite no evidence of foliar K uptake, an effect of leaf anion concentrations was observed, indicating that foliar nutrient sprays may influence leaf and leaf surface anion balance.
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Ball, O. B., Prescher, C., Appel, K., Baehtz, C., Baron, M. A., Briggs, R., et al. (2023). Dynamic optical spectroscopy and pyrometry of static targets under optical and x-ray laser heating at the European XFEL. Journal Of Applied Physics, 134(5).
Résumé: Experiments accessing extreme conditions at x-ray free electron lasers (XFELs) involve rapidly evolving conditions of temperature. Here, we report time-resolved, direct measurements of temperature using spectral streaked optical pyrometry of x-ray and optical laser-heated states at the High Energy Density instrument of the European XFEL. This collection of typical experiments, coupled with numerical models, outlines the reliability, precision, and meaning of time dependent temperature measurements using optical emission at XFEL sources. Dynamic temperatures above 1500 K are measured continuously from spectrally- and temporally-resolved thermal emission at 450-850 nm, with time resolution down to 10-100 ns for 1-200 μs streak camera windows, using single shot and integrated modes. Targets include zero-pressure foils free-standing in air and in vacuo, and high-pressure samples compressed in diamond anvil cell multi-layer targets. Radiation sources used are 20-fs hard x-ray laser pulses at 17.8 keV, in single pulses or 2.26MHz pulse trains of up to 30 pulses, and 250-ns infrared laser single pulses. A range of further possibilities for optical measurements of visible light in x-ray laser experiments using streak optical spectroscopy are also explored, including for the study of x-ray induced optical fluorescence, which often appears as background in thermal radiation measurements. We establish several scenarios where combined emissions from multiple sources are observed and discuss their interpretation. Challenges posed by using x-ray lasers as non-invasive probes of the sample state are addressed. (c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0142196
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Banjan, M., Crouzet, C., Sabatier, P., Jomard, H., Bajard, M., Demory, F., et al. (2023). Did the Younger Dryas to Holocene climate transition favour high seismicity rates in the north-western Alps? Sedimentology, 70(2), 538–568.
Résumé: In the French north-western Alps, several lakes of glacial origin, such as Aiguebelette and La Thuile, present some mass-transport deposits within their sedimentary sequences. These event layers can result from lake sediment destabilization eventually triggered by earthquakes. On Lake Aiguebelette, based on sedimentological, geochemical and magnetic analyses, and high-resolution seismic and bathymetric surveys a ca 1 m thick event layer was identified in the deepest lake basin and a synchronous ca 2 cm thick deposit in the shallow basin. Age-depth models based on radiocarbon ages reveal that both mass-transport deposits in Lake Aiguebelette occurred around the Younger Dryas – Early Holocene climatic transition (i.e. 11 700 cal bp) time range. In Lake La Thuile, located 30 km away, unique mass-transport deposits (translational slide type) were recorded at the same time range in sedimentary records. Additionally, high-resolution seismic profiles previously acquired in Lake Annecy and Lake Bourget support the hypothesis of significant mass-transport deposits occurring at the Younger Dryas – Early Holocene time range. These outcomes on four north-western peri-Alpine and Alpine lakes highlight the regional occurrence of mass-transport deposits in the Younger Dryas – Early Holocene time range. Seismic and rockfall events are discussed as potential sources of these significant and similarly aged mass-transport deposits. Based on this study and a literature review, the authors suggest that mechanisms induced by rapid climate change and glacial retreat, such as crustal rebound and erosional unloading, could favour the triggering of earthquakes and rockfall events. In the case of mass-transport deposits archived in north-western Alpine lakes during this time period, this study favours the hypothesis of increased seismicity as the primary source driving process involved.
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Barajas, A., Journeau, C., Obara, K., & Shapiro, N. M. (2023). Comparison of Continuously Recorded Seismic Wavefields in Tectonic and Volcanic Environments Based on the Network Covariance Matrix. Journal Of Geophysical Research-Solid Earth, 128(12).
Résumé: Extended and sufficiently dense seismic networks capture spatiotemporal properties of the continuously recorded wavefields and can be used to compute the level of their coherence at different frequencies via the analysis of the network covariance matrix, which has been successfully used to study volcanic seismicity. Here, we present an application of the covariance matrix method in a subduction zone environment. We show that most coherent signals identified through the covariance matrix analysis are related to regional earthquakes with the wavefield properties affected by the scattering, which depends on the source location. Tectonic tremors, on the other hand, are not characterized by a high level of coherence. We compare real data results with a set of synthetic tests aimed at mimicking the properties of seismic sources and the main features of wave propagation. We conclude that highly coherent volcanic tremor wavefields could be produced in two ways: by a spatially localized group of monochromatic seismic sources or by a single source located in a highly heterogeneous medium. In both cases, the stability of the source position is a necessary condition to reproduce the observations in volcanoes. On the other hand, the low coherence of tectonic tremor wavefields can be explained by a spatially extended distribution of sources, in agreement with large portions of the subduction interface being nearly simultaneously involved in the episodes of slow deformation. In addition to earthquakes, weak and nearly continuous seismic signals known as “seismic tremors” are observed in the vicinity of active volcanoes and large seismic faults. They are related to slow processes that lead to accumulation of energy released during catastrophic events such as large eruptions and earthquakes. The exact mechanisms generating seismic tremors remain elusive. Possible physical processes include variations of the fluid pressure, slow deformation and rupturing of rocks. In order to better understand possible analogies and differences between seismic tremors occurring in the volcanic and the tectonic environments, we compare observations from the Kyuchevskoy group of volcanos in Kamchatka, Russia and from the Nankai subduction zone in Japan. We apply a mathematical formalism called “network-based covariance matrix analysis” that is based on correlating signals recorded by a network of seismographs. Our results show significant differences between the distribution of sources of volcanic and tectonic tremors. For the former, the sources are found to be very localized in space and stable in time while the latter are generated by a spatially broad and variable in time distribution of sources, in agreement with large portions of the subduction interface being nearly simultaneously involved in the episodes of slow earthquakes. We compare deep volcanic and tectonic tremors continuously recorded by regional-scale seismic networksVolcanic tremor wavefields are characterized by high level of spatial coherence across the networkLow level of coherence of tectonic tremor wavefields can be explained by a spatially extended distribution of their sources
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Barelli, M., Casado, S., Cassin, F., Pimentel, C., Pina, C. M., Giordano, M. C., et al. (2023). Highly efficient sequestration of aqueous lead on nanostructured calcite substrates. Nanotechnology, 34(36).
Résumé: Following defocused ion beam sputtering, large area highly corrugated and faceted nanoripples are formed on calcite (10.4) faces in a self-organized fashion. High resolution atomic force microscopy (AFM) imaging reveals that calcite ripples are defined by facets with highly kinked (11.0) and (21.12) terminations. In situ AFM imaging during the exposure of such modified calcite surfaces to PbCl2 aqueous solution reveals that the nanostructured calcite surface promotes the uptake of Pb. In addition, we observed the progressive smoothing of the highly reactive calcite facet terminations and the formation of Pb-bearing precipitates elongated in registry with the underlying nanopattern. By SEM-EDS analysis we quantified a remarkable 500% increase of the Pb uptake rate, up to 0.5 atomic weight % per hour, on the nanorippled calcite in comparison to its freshly cleaved (10.4) surfaces. These results suggest that nanostructurated calcite surfaces can be used for developing future systems for lead sequestration from polluted waters.
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Barlas, N. T., Bahamonde, H. A., Pimentel, C., Dominguez-Huidobro, P., Pina, C. M., & Fernandez, V. (2023). Evaluating Leaf Wettability and Salt Hygroscopicity as Drivers for Foliar Absorption. Plants-Basel, 12(12).
Résumé: The objective of this study was to evaluate the rate of foliar absorption of magnesium (Mg) salts with different deliquescence and efflorescence relative humidity values (DRH and ERH, also known as point of deliquescence (POD) and point of efflorescence (POE), respectively) when supplied to leaves of model plants with different wettability properties. For this purpose, a greenhouse pot experiment was conducted with lettuce (very wettable), broccoli (highly unwettable) and leek (highly unwettable). Foliar sprays contained 0.1% surfactant plus 100 mM Mg supplied as MgCl2 & BULL;6H(2)O, Mg(NO3)(2)& BULL;6H(2)O or MgSO4 & BULL;7H(2)O. Leaf Mg concentrations were determined 1 and 7 days after foliar application. Anion concentrations were also measured in lettuce where a significant foliar Mg absorption was detected. Leaf wettability, leaf surface free energy and fertilizer drop deposit appearance onto the foliage were assessed. It is concluded that despite including a surfactant in the spray formulation, leaf wettability plays a major role in foliar Mg absorption.
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Barras, F., Thogersen, K., Aharonov, E., & Renard, F. (2023). How Do Earthquakes Stop? Insights From a Minimal Model of Frictional Rupture. Journal Of Geophysical Research-Solid Earth, 128(8).
Résumé: The question “what arrests an earthquake rupture?” sits at the heart of any potential prediction of earthquake magnitude. Here, we use a one-dimensional, thin-elastic-strip, minimal model, to illuminate the basic physical parameters that may control the arrest of large ruptures. The generic formulation of the model allows for wrapping various earthquake arrest scenarios into the variations of two dimensionless variables (tau) over bar (kappa) (initial dimensionless stress parameter on the fault) and (G) over bar (c) (dimensionless fracture energy), valid for both in-plane and antiplane shear loading. Our continuum model is equivalent to the standard Burridge-Knopoff model, with an added characteristic length scale, H, that corresponds to either the thickness of the damage zone for strike-slip faults or to the thickness of the downward moving plate for subduction settings. We simulate the propagation and arrest of frictional ruptures and derive closed-form expressions to predict rupture arrest under different conditions. Our generic model illuminates the different energy budget that mediates crack- and pulse-like rupture propagation and arrest. It provides additional predictions such as generic stable pulse-like rupture solutions, stress drop independence of the rupture size, the existence of back-propagating fronts, and predicts that asymmetric slip profiles arise under certain pre-stress conditions. These diverse features occur also in natural earthquakes, and the fact that they can all be predicted by a single minimal framework is encouraging and pave the way for future developments of this model. Plain Language Summary Untangling the dynamics that governs the propagation and arrest of earthquakes is still challenging, mainly because of the few constraints available on the fault zone geometry, the constitutive properties of fault materials, as well as fault rheology during the rupture event. The present study aims at formulating a model containing a minimal number of parameters to describe the dynamics of large earthquakes. Despite its simplicity, this minimal model is able to reproduce several salient features of natural earthquakes that are still debated (e.g., various arrest scenarios, stable pulse-like rupture, back-propagating front, asymmetric slip profiles). We demonstrate how the proposed model can be used to simulate the propagation and arrest of large earthquakes, which are controlled by local variations of shear stress and material properties on the fault. With this simple and generic description, the proposed model could be readily extended to account for additional processes controlling the dynamics of large earthquakes.
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Bascou, P., & Jouanne, F. (2023). Quantification and modelling of post-seismic deformation following the 2013 September 24 <i>M</i><sub>w</sub> 7.7 earthquake in the Makran region, Pakistan. Geophysical Journal International, 233(2), 999–1017.
Résumé: On 2013 September 24, an earthquake of magnitude M-w 7.7 occurred on the Hoshab Fault in southern Pakistan, south of the 650-km-long Chaman Fault, within the eastern Makran accretionary wedge. This earthquake was caused predominantly by strike-slip faulting. To quantify the post-seismic deformation following this large earthquake, we used ascending and descending Sentinel-1 data over the period 2014 November-2017 December. The deformation time-series over these 3 years shows that the post-seismic deformation was not linear over the time. To determine the mechanisms that may have driven post-seismic deformation, such as after-slip or a combination of after-slip and viscous relaxation, we explored some models, including after-slip only, and a combination of after-slip and viscous relaxation, to identify the best fit between the observed and simulated deformation time-series. Our results indicate that after-slip was the main mechanism controlling the post-seismic deformation. The introduction of a basal flat fault in the modelling improves the fit between the model results and the time-series obtained from the satellite images This basal fault is located at a depth of 18 km, has a northward dip of 7 degrees and corresponds to the basal decollement level of the Makran accretionary prism.
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Batanova, V. G., & Sobolev, A. V. (2023). Development of Reference Materials for Microanalysis in Geosciences: The Case of Olivine MongOL Sh11-2. Microscopy and microanalysis : the official journal of Microscopy Society of America, 29(Supplement_1), 227–228.
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Bazarkina, E. F., Zotov, A. V., Chareev, D. A., Truche, L., & Tarnopolskaya, M. E. (2023). Cadmium Behavior in Sulfur-bearing Aqueous Environments: Insight from CdS Solubility Measurements at 25-80°C. Geology Of Ore Deposits, 65(1), 28–43.
Résumé: The present experimental study explores the effects of temperature and sulfur in Cd aqueous geo-chemistry under reduced conditions. Greenockite CdS solubility is measured in H2O-H2S-HClO4-NaHS solutions at 25-80 degrees C as a function of pH and sulfur concentration. Based on solubility product measurements in highly acid solutions, the standard thermodynamic properties of greenockite (CdS) are revised, and the recommended value of Delta(integral)G(298.15)(0) for greenockite CdS(s) is -151.5 +/- 0.3 kJ mol(-1). The stability of greenockite (CdS) is higher than predicted by calculations using previous literature data. At 80 degrees C, the stability constants for Cd-HS complexes are measured for the first time, the values are 10(-5.65 +/- 1.00) for CdS(s) + H+ = CdHS+, 10(-6.00 +/- 0.40) for CdS(s) + H2S(aq)0 = Cd(HS)(2(aq))(0), 10(-3.87 +/- 0.10) for CdS(s) + H2S(aq)0 + HS- = Cd(HS)(3)(-), and 10(-3.53 +/- 0.20) for CdS(s) + H2S(aq)0 + 2HS- = Cd(HS)(4)(2-). Modeling of Cd behavior at 3-200 degrees C shows that Cd-HS species are more important than previously believed. The fraction of Cd(HS)(n)(2-n) (n = 1-4) complexes increases with m H2S and decreases with T. Thus, in euxinic marine environments with m H2S >= 10(-5), Cd speciation changes from Cd-Cl to Cd-HS. This speciation change is expected to affect Cd isotope fractionation and should be accounted for when applying Cd isotopic signature as a paleo tracer in marine sediments. The new thermodynamic data are indispensable for modeling Cd behavior in response to pH, T, and m H2S. As a function of these parameters, sulfur has the main control on Cd geochemistry being the main factor of Cd precipitation at low m H2S and favoring Cd mobilization at high m H2S.
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Berezhnev, Y., Belovezhets, N., Shapiro, N., & Koulakov, I. (2023). Temporal changes of seismic velocities below Bezymianny volcano prior to its explosive eruption on 20.12.2017. Journal Of Volcanology And Geothermal Research, 433.
Résumé: The strong explosive eruption of Bezymianny volcano (Klychevskoy volcano group) occurred on 21 December 2017, the preparation phases of which were recorded by a local seismic network. Applying methods of estimation of seismic velocity changes based on cross-correlation of ambient noise, we obtained different velocity variations at several passbands before the eruption. In order to explain the observations obtained, we performed qualitative mechanical estimates of stress changes resulting from the migration of the pressure source. The obtained and estimated velocity changes have the same patterns. We propose that observed and evaluated velocity changes are caused by fluids migration from mid-crustal magma reservoir of the Bezymianny volcano to the shallow magma chamber that then triggered the eruption.
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Bilau, A., Bienveignant, D., Rolland, Y., Schwartz, S., Godeau, N., Guihou, A., et al. (2023). The Tertiary structuration of the Western Subalpine foreland deciphered by calcite-filled faults and veins. Earth-Science Reviews, 236.
Résumé: The age of brittle deformation in the superficial part of orogens is generally constrained by relative, cross-cutting structural relationships. However, it becomes possible to decipher the timing of fault activity by a combination of methods based on U-Pb dating and stable isotope composition of calcite-filled fault and veins. This methodology is applied to constrain the timing of deformation of the frontal part of an orogenic system, through the example of the Tertiary development of subalpine massifs fold and thrust belt (composed by Bauges, Chartreuse, Vercors massifs). The architecture of the massifs is well constrained, but the chronology and the nature of involved fluids is unknown. Clumped isotope Delta 47 analysis shows a significant variation of fluid temperature from 54 degrees C to the west up to 149 degrees C for the internal Vercors thrust to the east. These temperature estimates highlight a deep underthrusting with a significant exhumation of the eastern Vercors (4-6 km), while a shallow underthrusting at a depth of around 2 km is estimated for the central Vercors. Carbon and oxygen stable isotope analyses, reveal three fluid signatures corresponding to heated fluids from meteoric or basin-derived origin, which interacted at various extents with the host-rock. These data are in agreement with a low altitude frontal belt, and with a progressive reequilibration of downwards infiltrating fluids with the composition of the host-rocks. The successfully dated calcites are those exhibiting the highest fluid-rock ratios, which allowed U enrichment in a mainly uranium-poor rock environment. In-situ U-Pb calcite dating was performed on fault mirrors of main thrusts and on fractured pebbles of the underthrusted molasses of eight major thrusts. Preserved Oligocene ages of extensional veins related to pre-Alpine rifting demonstrate that U-Pb calcite is a robust method to characterize multiple superimposed events of a whole mountain building history. Furthermore, the presence of multiple deformation events in the same location point out the importance of inherited structures on the strain localization processes. Thrust related U-Pb on calcite ages on an E-W section between the Vercors and Chartreuse massifs record a major Miocene shortening phase, and the timing of strain propagation towards the foreland. The oldest thrust dated at 15 Ma, corresponds to the activation of the most internal preserved thrust mobilizing 149 degrees C fluids. In the central subalpine massifs, ages range from 14 Ma (Chartreuse) to 12 Ma (Vercors) mobilizing 54 degrees C fluids. On the western part, the initiation of the most external thrust has been dated between 10 Ma and 7 Ma. These geochronological constraints are consistent with an 'in-sequence' westward propagation of the deformation between 15 Ma and 7 Ma and contemporaneous with the exhumation of the Belledonne External Crystalline Massif and the development of flexural basin sedimentation. Paleostress calculations indicate a threestage evolution of the subalpine nappe stack. Reverse and strike-slip deformations are interpreted as a diffuse tectonic reactivation in an 'hors-sequence' mode from 10 Ma to present in a broadly similar stress field.
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Bilau, A., Rolland, Y., Dumont, T., Schwartz, S., Godeau, N., Guihou, A., et al. (2023). Early onset of Pyrenean collision (97-90 Ma) evidenced by U-Pb dating on calcite (Provence, SE France). Terra Nova, 35(5), 413–423.
Résumé: Early Late Cretaceous uplift of Provence gave rise to the Durance Isthmus. In the present study, U-Pb dating on calcite of compressional structures related to Pyrenean foreland compressional deformation in Provence shows that N-S shortening occurred coeval with emersion of the Durance Isthmus, through the development of combined top-to-the-North to NW thrusts between 97 and 90 Ma. This large-scale event, recorded from the Pyrenees to the Middle-East regions is interpreted as a far-field internal plate precursor of the Africa-Europe plates reorganization. Furthermore, the change in tectonic style and amount of shortening between Provence and Pyrenees was accommodated by sinistral reactivation of the NE-SW Cevennes and Nimes faults, acting as transform boundaries in this incipient collisional context.
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Bindeman, I. N., Melnik, O. E., Guillong, M., Utkin, I. V., Wotzlaw, J. -f., Schmitt, A. K., et al. (2023). Age of the magma chamber and its physicochemical state under Elbrus Greater Caucasus, Russia using zircon petrochronology and modeling insights. Scientific Reports, 13(1).
Résumé: Mount Elbrus, Europe's tallest and largely glaciated volcano, is made of silicic lavas and is known for Holocene eruptions, but the size and state of its magma chamber remain poorly constrained. We report high spatial resolution U-Th-Pb zircon ages, co-registered with oxygen and hafnium isotopic values, span similar to 0.6 Ma in each lava, documenting magmatic initiation that forms the current edifice. The best-fit thermochemical modeling constrains magmatic fluxes at 1.2 km(3)/1000 year by hot (900 degrees C), initially zircon-undersaturated dacite into a vertically extensive magma body since similar to 0.6 Ma, whereas a volcanic episode with eruptible magma only extends over the past 0.2 Ma, matching the age of oldest lavas. Simulations explain the total magma volume of similar to 180 km(3), temporally oscillating delta O-18 and epsilon Hf values, and a wide range of zircon age distributions in each sample. These data provide insights into the current state (similar to 200 km(3) of melt in a vertically extensive system) and the potential for future activity of Elbrus calling for much-needed seismic imaging. Similar zircon records worldwide require continuous intrusive activity by magmatic accretion of silicic magmas generated at depths, and that zircon ages do not reflect eruption ages but predate them by similar to 10(3) to 10(5) years reflecting protracted dissolution-crystallization histories.
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Bissardon, C., Proux, O., Gazze, S. A., Filhol, O., Toubhans, B., Sauzeat, L., et al. (2023). Intracellular Fate of Sub-Toxic Concentration of Functionalized Selenium Nanoparticles in Aggressive Prostate Cancer Cells. Nanomaterials, 13(23).
Résumé: Selenium 0 (Se0) is a powerful anti-proliferative agent in cancer research. We investigated the impact of sub-toxic concentrations of Se0 functionalized nanoparticles (SeNPs) on prostate cancer PC-3 cells and determined their intracellular localization and fate. An in-depth characterization of functionalized selenium nanoparticles composition is proposed to certify that no chemical bias relative to synthesis issues might have impacted the study. Selenium is an extremely diluted element in the biological environment and therefore requires high-performance techniques with a very low detection limit and high spatial resolution for intracellular imaging. This was explored with state-of-the-art techniques, but also with cryopreparation to preserve the chemical and structural integrity of the cells for spatially resolved and speciation techniques. Monodisperse solutions of SeNPs capped with bovine serum albumin (BSA) were shown to slow down the migration capacity of aggressive prostate cancer cells compared to polydisperse solutions of SeNPs capped with chitosan. BSA coating could prevent interactions between the reactive surface of the nanoparticles and the plasma membrane, mitigating the generation of reactive oxygen species. The intracellular localization showed interaction with mitochondria and also a localization in the lysosome-related organelle. The SeNPs-BSA localization in mitochondria constitute a possible explanation for our result showing a very significant dampening of the PC-3 cell proliferation capabilities. The purpose of the use of sublethal compound concentrations was to limit adverse effects resulting from high cell death to best evaluate some cellular changes and the fate of these SeNPs on PC-3. Our findings provide new insight to further study the various mechanisms of cytotoxicity of SeNPs.
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Borisova, A. Y., Melnik, O. E., Gaborit, N., Bindeman, I. N., Traillou, T., Raffarin, M., et al. (2023). In situ probing of the present-day zircon-bearing magma chamber at Krafla, Northeastern Iceland. Frontiers In Earth Science, 11.
Résumé: Active felsic magmatism has been rarely probed in situ by drilling but one recent exception is quenched rhyolite sampled during the 2009 Iceland Deep Drilling Project (IDDP). We report finding of rare zircons of up to similar to 100 μm in size in rhyolite glasses from the IDDP-1 well products and the host 1724 AD Viti granophyres. The applied SHRIMP U-Th dating for both the IDDP and the Viti granophyre zircons gives zero-age (+/- 2 kyr), and therefore suggests that the IDDP-1 zircons have crystallized from an active magma intrusion rather than due to the 20-80 ka post-caldera magmatic episodes recorded by nearby domes and ridges. Ti-in-zircon geothermometer for Viti granophyre reveals zircon crystallization temperatures similar to 800 degrees C-900 degrees C, whereas IDDP-1 rhyolite zircon cores show Ti content higher than 100 ppm, corresponding to temperatures up to similar to 1,100 degrees C according to the Ti-in-zircon thermometer. According to our thermochemical model at such elevated temperatures as 1,100 degrees C, rhyolitic magma cannot be saturated with zircon and zircon crystallization is not possible. We explain this controversy by either kinetic effects or non-ideal Ti incorporation into growing zircons at low pressures that start to grow from nucleus at temperatures similar to 930 degrees C. High temperatures recorded by IDDP-1 zircon together with an occurrence of baddeleyite require that the rhyolite magma formed by partial melting of the host granophyre due to basaltic magma intrusion. Zr concentration profiles in glass around zircons are flat, suggesting residence in rhyolitic melt for >4 years. In our thermochemical modeling, three scenarios are considered. The host felsite rocks are intruded by: 1) a basaltic sill, 2) rhyolite magma 3) rhyolite sill connected to a deeper magmatic system. Based on the solution of the heat conduction equation accounting for the release of latent heat and effective thermal conductivity, these data confirm that the rhyolite magma could be produced by felsic crust melting as a result of injection of a basaltic or rhyolite sill during the Krafla Fires eruption (1975 AD).
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Boschetti, L., Schwartz, S., Rolland, Y., Dumont, T., & Nouibat, A. (2023). A new tomographic-petrological model for the Ligurian-Provence back-arc basin (North-Western Mediterranean Sea). Tectonophysics, 868.
Résumé: The nature of the crystalline basement of the Ligurian-Provence back-arc (LPB) basin is a matter debate as it remains unexplored by direct drilling methods. Several models have been proposed for the lower crustal structure comprising hyperextended continental crust or serpentinized mantle. In this paper, a new Vp-Vs geophysical dataset and corresponding tomography are used to propose a new petrological model for the LPB basin and for the formation of the crust of this back-arc domain. By crossing values of Vp, Vs and Vp/Vs ratios, the Messinian salt layer can be clearly identified down to 5 km depth, which highlights salt diapir structures into its overlying sedimentary cover. The 7.5 km depth corresponds to the transition with a heterogeneous basaltic oceanic crust about 4.5-5 km thick, intruded by rounded felsic gabbro plutons and underplated by a more mafic/ ultramafic gabbro. This latter results from fractional crystallization of a hydrous magma inherited from the melting of a supra-subduction mantle which interacted with fluids originating from the subducting Adria slab. These magmas can be traced at the surface by magnetic anomalies punctuating the studied profile. Those new data and observations lead to conclude that the crust of the LPB basin resulted from a fast oceanic accretion during the opening of the back-arc. Its nature remains comparable to an immature oceanic crust with an overall basaltic and gabbroic composition and appears devoid of any serpentinized exhumed mantle.
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Bosse, L., Lilensten, J., Gillet, N., Brogniez, C., Pujol, O., Rochat, S., et al. (2023). Night light polarization: Modeling and observations of light pollution in the presence of aerosols and background skylight or airglow. Journal Of Atmospheric And Solar-Terrestrial Physics, 246.
Résumé: We introduce a new polarized radiative transfer model able to compute the polarization measured by a virtual instrument in a given nocturnal environment recreating real world conditions (1-dimensional atmospheric and aerosol profiles, 3-dimensional light sources with complex and widespread geometries, terrain obstructions). Initially developed to address the issue of aurorae and nightglow polarization, the model has potential applications in the context of light pollution, or aerosols and air pollution measurements in night time conditions. We provide the physical assumptions behind the model together with the main points regarding its numerical implementation, together with the inherent constraints and liberties it brings. The model, based on single scattering equations in the atmosphere, is first tested on a few simple configurations to assess the effect of several key parameters in controlled environments. The model outputs are then compared to field measurements obtained in four wavelengths at mid-latitude in a dark valley of the French Alps, 20 km away from the closest city. In this context where the nightglow emissions are supposedly stationary and widespread, a convincing fit between the model predictions and observations is found in three wavelengths. This confrontation of ground-based records with our modeling constitutes a proof of concept for the investigation of our polarized environment in nocturnal conditions, in the presence of localized and/or extended sources. It calls for further investigations. In particular we discuss the future need for inter-calibrating the sources and the polarimeter in order to optimally extract the information contained in such measurements, and how multiple-scattering (not implemented in the present study) could impact our observations and their interpretation.
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Branco, F. R., Callefo, F., Zezzi Arruda, M. A., Pessoa, G. D. S., Franca Barreto, A. M., Ghilardi, A. M., et al. (2023). Early Diagenesis Of Seeds Associated With Limestones Soils. Palaios, 38(3), 158–171.
Résumé: Early diagenesis of fossil plants, especially of their reproductive structures, provides essential information about the evolution of the group. In this study, we describe the morphology and early fossil diagenesis of isolated eudicot seeds collected in neosols (entisols) derived from limestones of Romualdo Formation, Araripe Basin, Brazil. They were studied using scanning electron microscopy, X-ray microtomography, and laser ablation inductively coupled plasma mass spectrometry in the imaging mode. The seeds were three-dimensionally preserved with volumes ranging from 10.16 to 18.57 mm(3). The morphology and anatomy are described, and the specimens are identified as Fabidae seeds. It is known that Fabidae arose in the mid-late Cretaceous, so the seeds were considered diachronic to the paleobiota from the Romualdo Formation, not belonging to this stratigraphy. Based on the spectrometric intensities of the mapped elements, such as C, Fe, Si, and Cu, intensity images were elaborated on these elements on the surface and inside the seeds. The maps indicated higher intensities of C, Fe, Si, and Cu in the seed tissues than those in modern seeds, suggesting an early stage of diagenesis. The calcareous sandstones of the Romualdo Formation may have contributed charged ions carried by meteoric water and groundwater, and they later precipitated in the organic tissues, triggering the start of diagenesis in the soil.
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Brenner, S., Horvat, C., Hall, P., Lo Piccolo, A., Fox-Kemper, B., Labbe, S., et al. (2023). Scale-Dependent Air-Sea Exchange in the Polar Oceans: Floe-Floe and Floe-Flow Coupling in the Generation of Ice-Ocean Boundary Layer Turbulence. Geophysical Research Letters, 50(23).
Résumé: Sea ice is a heterogeneous, evolving mosaic of individual floes, varying in spatial scales from meters to tens of kilometers. Both the internal dynamics of the floe mosaic (floe-floe interactions), and the evolution of floes under ocean and atmospheric forcing (floe-flow interactions), determine the exchange of heat, momentum, and tracers between the lower atmosphere and upper ocean. Climate models do not represent either of these highly variable interactions. We use a novel, high-resolution, discrete element modeling framework to examine ice-ocean boundary layer (IOBL) turbulence within a domain approximately the size of a climate model grid. We show floe-scale effects could cause a marked increase in the production of fine-scale three-dimensional turbulence in the IOBL relative to continuum model approaches, and provide a method of representing that turbulence using bulk parameters related to the spatial variance of the ice and ocean: the floe size distribution and the ocean kinetic energy spectrum. Sea ice is a complex broken mosaic of individual pieces, called floes. These floes control how heat and momentum move between the atmosphere and ocean. But these floes interact with each other as well as with the upper ocean and lower atmosphere, and this means that these exchanges can be complexly related to both types of processes: floe-floe and floe-flow. Using experiments that explicitly evolve sea ice floes interacting with each other and the upper ocean, we develop a formulation for how momentum is transferred between the ice and ocean as a function of simple parameters of the ice-ocean system that may be available to climate models. Discrete element model results show floe-size-dependent ice-ocean boundary layer (IOBL) stress-driven turbulenceIOBL turbulence is driven both by floe collisional velocity and by floe-scale ocean variabilityWe present a framework for a scale-aware parameterization of IOBL turbulence using bulk parameters
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Bushenkova, N., Koulakov, I., Bergal-Kuvikas, O., Shapiro, N., Gordeev, E. I., Chebrov, D. V., et al. (2023). Connections between arc volcanoes in Central Kamchatka and the subducting slab inferred from local earthquake seismic tomography. Journal Of Volcanology And Geothermal Research, 435.
Résumé: The area of Central Kamchatka limited by latitudes of 52.5 and 54 degrees includes six active volcanoes (Avacha, Koryaksky, Zhupanovsky, Mutnovsky, Gorely and Opala), as well as a number of dormant and extinct strato-volcanoes, monogenic cones and large calderas. Furthermore, it contains the Malko-Petropavlovsk fracture zone (MPZ), which marks the boundary between two distinct subduction regimes to the south and to the north. We present a new seismic tomography model for this area, which was constructed based on the joint use of data of the Kamchatkan permanent seismic stations and a temporary network installed in the region in 2019-2020. A series of synthetic tests have demonstrated fair resolution of the derived seismic velocity structures in the crust and in the mantle wedge down to-150 km. The distributions of the P and S wave velocities, and especially the Vp/Vs ratio, clearly highlight the connection between the volcanic centers in Central Kamchatka and the sub -ducting slab. At depths below 40 km depth, we observe two large low-velocity anomalies centered below Zhupanovsky and Mutnovsky volcanoes and covering all other volcanoes in the area. In the vertical sections, the corresponding anomalies of high Vp/Vs ratio have mushroom shapes with the heads spreading along the bottom of the crust, which probably represent the underplating of magma material that feeds the volcanoes of the groups. The tomography results also reveal some important tectonic features, such as a V-shaped fault system in the Avacha Graben, which is the part of the MPZ.
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Caballero, E., Duputel, Z., Twardzik, C., Rivera, L., Klein, E., Jiang, J., et al. (2023). Revisiting the 2015 M<sub>w</sub>=8.3 Illapel earthquake: unveiling complex fault slip properties using Bayesian inversion. Geophysical Journal International, 235(3), 2828–2845.
Résumé: The 2015 moment magnitude M-w = 8.3 Illapel earthquake is the largest mega-thrust earthquake that has been recorded along the Chilean subduction zone since the 2010 M-w = 8.8 Maule earthquake. Previous studies indicate a rupture propagation from the hypocentre to shallower parts of the fault, with a maximum slip varying from 10 to 16 m. The amount of shallow slip differs dramatically between rupture models with some results showing almost no slip at the trench and other models with significant slip at shallow depth. In this work, we revisit this event by combining a comprehensive data set including continuous and survey GNSS data corrected for post-seismic and aftershock signals, ascending and descending InSAR images of the Sentinel-1A satellite, tsunami data along with high-rate GPS, and doubly integrated strong-motion waveforms. We follow a Bayesian approach, in which the solution is an ensemble of models. The kinematic inversion is done using the cascading capability of the AlTar algorithm, allowing us to first get a static solution before integrating seismic data in a joint model. In addition, we explore a new approach to account for forward problem uncertainties using a second-order perturbation approach. Results show a rupture with two main slip patches, with significant slip at shallow depth. During the rupture propagation, we observe two regions that are encircled by the rupture, with no significant slip, westward of the hypocentre. These encircling effects have been previously suggested by back-projection results but have not been observed in finite-fault slip models. We propose that the encircled regions correspond to zones where the yield stress largely exceeds the initial stress or where fracture energy is too large to be ruptured during the Illapel earthquake. These asperities may potentially break in the future and probably already broke in the past.
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Cabrera, L., & Poli, P. (2023). A Struggled Rupture Initiation of the <i>M</i><sub>w</sub> 6.1 2009 L'Aquila Earthquake. Geophysical Research Letters, 50(6).
Résumé: Understanding under which physical conditions large earthquakes begin, is a key question in Earth science. Laboratory experiments and numerical models have shown that earthquake nucleation has distinct phases: a quasi-static and an acceleration stage, followed by dynamic propagation. However, obtaining observations of such or similar processes in nature is complex. Here, we report on the rupture initiation of the M-w 6.1 2009 L'Aquila earthquake. From the detailed analysis of seismic waves recorded at several stations, we identify an similar to 0.6-s signal preceding the large dynamic rupture. From the geometrical characterization and rupture parameters of this initial phase, we infer that the rupture struggled to initiate exhibiting a slow rupture velocity (Vr=0.9 +/- 0.2 $Vr=0.9\pm 0.2$ km/s) and low seismic efficiency (eta=0.24 $\eta =0.24$) due to a complex environment in the region where the rupture starts. We also show that the parameters of the rupture initiation are representative of scale-dependent quantities for slip-dependent nucleation models.
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Cabrera-Perez, I., D'Auria, L., Soubestre, J., Przeor, M., Barrancos, J., Garcia-Hernandez, R., et al. (2023). Spatio-temporal velocity variations observed during the pre-eruptive episode of La Palma 2021 eruption inferred from ambient noise interferometry. Scientific Reports, 13(1).
Résumé: On Sept. 19th, 2021, a volcanic eruption began on the island of La Palma (Canary Islands, Spain). The pre-eruptive episode was characterized by seismicity and ground deformation that started only 9.5 days before the eruption. In this study, we applied seismic interferometry to the data recorded by six broadband seismic stations, allowing us to estimate velocity variations during the weeks preceding the eruption. About 9.5 days before the eruption, we observed a reduction in the seismic velocities is registered next to the eruptive centers that opened later. Furthermore, this zone overlaps with the epicenters of a cluster of volcano-tectonic earthquakes located at shallow depth (< 4 km) and detached from the main cluster of deeper seismicity. We interpret the decrease in seismic velocities and the occurrence of such a shallow earthquake cluster as the effect of hydrothermal fluid released by the ascending magma batch and reaching the surface faster than the magma itself.
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Cabrera-Perez, I., D'Auria, L., Soubestre, J., van Dorth, D. M., Cervigon-Tomico, G., Martin-Lorenzo, A., et al. (2023). Ambient Noise Tomography studies for geothermal exploration in the Canary Islands. Boletin Geologico Y Minero, 134(3), 7–25.
Résumé: Ambient Noise Tomography is a geophysical exploration technique that has proven to be highly efficient for studies at different scales and for multiple purposes, such as geothermal exploration. In this article, we introduce this technique by reviewing its various steps. Additionally, we present some examples of applications from studies conducted in the Canary Islands (specifically in Tenerife, Gran Canaria, and La Palma) for geothermal exploration purposes.The study realized in Gran Canaria reveals a series of low-velocity zones in the southern and eastern parts of the island, which could be linked to convective cells. In Tenerife, a low-velocity zone has been observed, potentially associated with a superficial clay cap that could facilitate the ascent of gases to the surface. Finally, the study carried out in La Palma highlights the existence of two low-velocity zones in the southern part of the island, possibly related to hydrothermally altered clay zones, indicating a circulation of hydrothermal fluids.
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Cabrera-Perez, I., Soubestre, J., D'Auria, L., Barrancos, J., Martin-Lorenzo, A., van Dorth, D. M., et al. (2023). Geothermal and structural features of La Palma island (Canary Islands) imaged by ambient noise tomography. Scientific Reports, 13(1).
Résumé: La Palma island is located in the NW of the Canary Islands and is one of the most volcanically active of the archipelago, therefore the existence of geothermal resources on the island is highly probable. The main objective of this work is to detect velocity anomalies potentially related to active geothermal reservoirs on La Palma island, by achieving a high-resolution seismic velocity model of the first few kilometres of the crust using Ambient Noise Tomography (ANT). The obtained ANT model is merged with a recent local earthquake tomography model. Our findings reveal two high-velocity zones in the island's northern and southern parts, that could be related to a plutonic intrusion and old oceanic crust materials. Conversely, four low-velocity zones are imaged in the southern part of the island. Two of them can be related to hydrothermal alteration zones located beneath the Cumbre Vieja volcanic complex. This hypothesis is reinforced by comparing the S-wave velocity model with the seismicity recorded during the pre-eruptive phase of the 2021 Tajogaite eruption, which revealed an aseismic volume coinciding with these low-velocity zones. Another low-velocity zone is observed in the southern part of the island, which we interpret as highly fractured rocks which could favour the ascent of hot fluids. A last low-velocity zone is observed in the central part of the island and associated with loose deposits generated by the Aridane valley mega landslide.
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Cabrera-Perez, I., Soubestre, J., D'Auria, L., van Dorth, D. M., Ledo, J., Pina-Varas, P., et al. (2023). Ambient noise tomography of Gran Canaria island (Canary Islands) for geothermal exploration. Geothermics, 108.
Résumé: Ambient noise tomography (ANT) has proved to be efficient in resolving crustal structures for different purposes. Despite the numerous studies carried out in Gran Canaria in the past for purposes of geothermal exploration, ANT had never been used before on this island. We applied this technique to understand Gran Canaria island's shallow structure, determining the 3-DS-wave velocity model of the island and focusing on its implications for geothermal exploration. We used data from 30 seismic stations installed between October 2019 and February 2020. Our findings revealed five relevant velocity anomalies helpful in understanding the island's geology and its geothermal potential. In particular, we identified two high-velocity anomalies in the central part of the island aligned with the primary northwest-southeast structural trends of Gran Canaria. We interpret them as evidence of intrusive volcanic bodies emplaced during the early stages of the island's geological history. We also identified three low-velocity zones located in different parts of the island. We maintain that these anomalies could be associated with porous and highly fractured materials produced during the more recent volcanic episodes. In addition, we observed a spatial correlation of anomalies in the electric conductivity identified in previous studies and strong lateral gradients in our S-wave velocity model. We interpret them as evidence of hydrothermal circulation and thermal anomalies in correspondence of lateral contacts between different geological units and/or faults.
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Carboni, A., Slomberg, D. L., Ouaksel, A., Brousset, L., Campos, A., Angeletti, B., et al. (2023). Matrix-driven environmental fate and effects of silver nanowires during printed paper electronics end of life. Environmental Science-Nano, 10(11), 3039–3050.
Résumé: The release of engineered nanomaterials (ENMs) during manufacturing, use and disposal of nano-enabled products (NEPs) is a potential route of environmental nanopollution. To date, there is limited knowledge on the ecological impact of ENMs incorporated in NEP matrices and how they compare to pristine nanoparticles. Here, we examined the fate and effect of silver nanowires (AgNWs) embedded in a cellulose matrix for the production of printed paper electronics (PPE) (nano)technologies. The fate and impact of fragmented AgNWs-PPE was monitored for 21 days in freshwater mesocosms mimicking a pond ecosystem. The Ag release and AgNWs-PPE behavior in water was further characterized in abiotic batch incubations. Qualitative and quantitative analyses were carried out to estimate the Ag partitioning between the environmental compartments and the aging of AgNWs-PPE as well as bioaccumulation and behavioral responses in biota. In contaminated pond mesocosms, the NEP cellulose/polyvinylidene chloride matrix resulted in rapid settling of the Ag on the sediments and prevented Ag release into the water column. The highest aqueous concentration measured corresponded to less than 0.5% of the total Ag introduced. The AgNWs-PPE fragments accumulated at the water sediment interface, where they were rapidly (bio)degraded and became bioavailable for benthic organisms. Aquatic snails accumulated a significant fraction of the Ag (1.4 +/- 0.5%) and displayed enhanced burrowing behavior in comparison to controls. In batch experiments, alteration of the ENM morphology was evident at the NEP surface. Here, the colocalization of Ag and S clusters suggests aging via sulfidation, similar to other pristine Ag ENMs. However, the cellulose matrix prevented weathering of the AgNWs within the NEP, which presented a near-pristine state even after 21 days of incubation. Overall, these results indicate that the fate and impact of Ag embedded in the AgNWs-PPE were driven by the cellulose matrix. In particular, given the specific properties and behavior of paper-based (nano)products, these may constitute a unique category when evaluating NEP environmental impact. The data gathered in this study can help in defining the environmental fate of such materials and provide useful information to address future studies focused on ENM environmental fate and risk assessment in a life-cycle perspective. The fate and impact of silver nanowires incorporated in a paper-based nano-enabled product (NEP) was investigated in freshwater mesocosms.
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Carlin, W., Malvoisin, B., Lanson, B., Brunet, F., Findling, N., Lanson, M., et al. (2023). FeIII-substituted brucite: Hydrothermal synthesis from (Mg0.8FeII0.2)-brucite, crystal chemistry and relevance to the alteration of ultramafic rocks. Applied Clay Science, 234.
Résumé: Ferroan brucite, (Mg,Fe)(OH)2, is a common mineral product of serpentinization reactions. The alteration of ferroan brucite under subsurface conditions is expected to form magnetite and hydrogen (H2). Ferroan brucite, (Mg0.8Fe0.2)(OH)2, with a grain size of 20-100 nm, was synthesized by precipitation of iron salts in the presence of NaOH under sub-anoxic conditions. Both composition and grain size of the synthetic product are similar to those of ferroan brucite found in serpentinized peridotites collected during the Oman Drilling Project. Synthetic ferroan brucite was then reacted in aqueous solutions at 378 and 403 K during 1 to 36 days either in PTFE-lined reactors or in gold capsules placed in externally heated pressure vessels. In gold capsules, ferroan brucite barely reacted and minor magnetite and H2 were produced. In PTFE-lined reactors, reaction progress over 75% could be achieved with reaction products composed of magnetite, pyroaurite [Mg6Fe2(OH)16(CO3)center dot 4.5H2O1, and a new phase, identified as ferrian brucite [(Mg0.8FeIII0.2)O0.2(OH)1.81 based on the Rietveld refinement of its X-ray powder diffraction data, FeIII/Fetot colorimetric determination and thermogravimetric analysis. Ferrian brucite is isostructural to ferroan brucite and displays the same iron/magnesium ratio. However, all iron is trivalent. X-ray diffraction and thermogravimetric data support deprotonation as the mechanism responsible for charge compensating FeII oxidation (Fe2+ + OH-=Fe3+ + O2-). The difference in reaction products obtained with the two types of reactors is attributed to the higher permeability to H2 (and/or O2) of the PTFE-lined reactors compared to gold capsules. Ferroan brucite conversion into ferrian brucite was unexpectedly fast and proceeded in a few days. The thermodynamic stability of ferrian brucite is discussed as a function of oxygen fugacity and pH.
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Castro-Cruz, D., Gatti, F., Lopez-Caballero, F., Hollender, F., El Haber, E., & Causse, M. (2023). Blind broad-band (0-10 Hz) numerical prediction of the 3-D near field seismic response of an M<sub>W</sub>6.0 extended fault scenario: application to the nuclear site of Cadarache (France). Geophysical Journal International, 232(1), 581–600.
Résumé: In this paper, physics-based numerical simulation (PBS) is employed to render a broad-band (0-10 Hz) realization of the near-field seismic response of the experimental nuclear site of Cadarache, located nearby the active Middle Durance Fault (southeastern France). The sensitivity of the earthquake numerical model to geological features is investigated by comparison with geophysical measurements and past aftershock and by highlighting the amplification induced by the soft sediments below Cadarache. The blind prediction of an M(W)6 target earthquake is approached by synthesizing four different finite-fault scenarios. The outcome is compared to the standard ground motion prediction equations (GMPEs), unveiling a possible GMPE overestimation of the pseudospectral acceleration ordinates at short natural periods, supporting the actual need to integrate synthetic and empirical predictions when direct observations are not available.
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Causse, M., Maufroy, E., Andre, L., & Bard, P. - Y. (2023). What Was the Level of Ground Motion across Europe during the Great AD 365 Crete Earthquake? Seismological Research Letters, 94(5), 2397–2410.
Résumé: Historical and archeological data report that an earthquake was felt over the whole eastern Mediterranean on 21 July A.D. 365. The impact of the tsunami it generated, which may have caused several thousands of fatalities, has been widely studied, whereas the impact of the seismic waves has hardly been explored. Here, we present simulations of the ground motion caused by the A.D. 365 event at 316 sites now instru-mented by seismological stations throughout Europe. The simulation approach is based on the modeling of a series of rupture scenarios coupled with empirical Green's func-tions (EGFs) obtained at the stations from a recent M-w 6.4 earthquake. The broadband and remarkably also the accelerometric records in urbanized areas can be exploited at distances as far as similar to 2000 km. Then, we use three empirical models to estimate the macroseismic intensity across Europe from the simulated peak ground accelerations and peak ground velocities. The presence of stations in thick sedimentary basins (lower Danube valley, Po plain, urban accelerometric network in the alpine valley of Grenoble) shows that local basin amplification effects can dominate acceleration values at frequencies favorable to human earthquake perception (similar to 0.5-1 Hz), even for basins located at more than 1500 km from the earthquake. Thus, our simulations indicate that the A.D. 365 earthquake was likely felt by the populations as far as the Po plain and as the city of Grenoble, about 1800 km away, and presumably in other large European basins such as the Pannonian basin. It is possible that the perception of the earthquake up to such distances contributed to its “universal” character perpetuated in archival sources. At closer distances (300-500 km), the simulated intensity levels indicate that the earthquake probably caused no damage.
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Chakraborty, S., Banerjee, D., Scheinost, A. C., Greneche, J. - M., Favre, F., Gehin, A., et al. (2023). Assessing the reactivity of Fe(II) sorbed on smectite surface towards U(VI) reduction. Journal Of Materials Research, 38(10), 2752–2763.
Résumé: The reactivity of Fe(II) sorbed on clay edges towards U(VI) reduction is investigated at pH 6.0 using Fe-free synthetic montmorillonite (MONT), Fe-poor natural montmorillonite (Fe-MONT) and Fe-rich natural nontronite (NAu-2). Partial reduction of U(VI) by sorbed Fe(II) only occurred on MONT but neither on Fe-MONT nor NAu-2. In the former case, the formation of a hydrated uranyl silicate (soddyite)-like phase is demonstrated by U L-III-edge EXAFS spectroscopy. Fe-57 Mossbauer spectrometry reveals that in this case 10% of the total sorbed Fe(II) was oxidized before- and an additional 6% after-addition of U(VI). The lack of reactivity towards U(VI) of Fe(II) sorbed on Fe-MONT or NAu-2 is likely due to inter-valence charge transfer (IVCT) between surface Fe(II) and structural Fe(III). The present study demonstrates that the reactivity of clay sorbed Fe2+ towards U(VI) strongly depends on the nature of clay and correspondingly on the oxidation state of sorbed Fe.
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Charlet, L., Tournassat, C., Greneche, J. - M., Wersin, P., Gehin, A., & Hadi, J. (2023). Mossbauer spectrometry insights into the redox reactivity of Fe-bearing phases in the environment. Journal Of Materials Research, 38(4), 958–973.
Résumé: Rates and mechanisms of important reactions in the cycling of electrons via the geochemical transformations of iron have been identified using Mossbauer spectrometry. The cycling of iron through various reservoirs (aquifer, soils, sediments, claystone) depends on high surface-area-to-volume ratios of Fe-bearing solids. The ability of Fe-bearing solids surfaces to interact chemically, through surface complexation, and ligand exchange mechanisms, with reductants such as Fe-II, and oxidants such as Se, U, Tc, Co, Eu, and O-2 facilitates electron transfer as well as dissolution and precipitation. Various pathways have been assessed on the basis of laboratory experiments for application to natural and engineered systems. Fe-II in the structure of layered silicates, oxides (e.g., Fe3O4) and hydrous oxides, and sulfides, as well as Fe-II surface complexes, such as on clay mineral edges, are very efficient reductants from a thermodynamic as well as from a kinetic point of view.
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Charlety, A., Le Breton, M., Baillet, L., & Larose, E. (2023). RFID Landslide Monitoring: Long-Term Outdoor Signal Processing and Phase Unwrapping. Ieee Journal Of Radio Frequency Identification, 7, 319–329.
Résumé: Localization of passive Radio-Frequency Identification (RFID) tags has been used to monitor landslide surface displacement since 5 years. This method, applied on slow displacements lower than 1cm per day, allows a high spatio-temporal resolution at a relatively low cost. With the feedback of the previous years, this paper proposes to summarize the various challenges encountered with the long-term outdoor RFID localization method, and presents data-processing solutions that were implemented to overcome these challenges. We propose a complex-smoothing unwrapping algorithm, a multi-frequency merging operation, as well as multi-tag and multi-antenna phase combining method. The concept of an unwrapping reference guide is presented and applied with groups of tags showing coherent displacements, or with absolute reference measurements. These approaches allow a higher data availability up to 38% for one site over multiple years, and a better phase unwrapping. Earth surface displacement monitoring with RFID proves to be a robust and accurate solution, with four equipped sites across France and Switzerland.
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Chauveau, D., Pastier, A. - M., de Gelder, G., Husson, L., Authemayou, C., Pedoja, K., et al. (2023). Unravelling the morphogenesis of coastal terraces at Cape Laundi (Sumba Island, Indonesia): Insights from numerical models. Earth Surface Processes And Landforms, .
Résumé: The morphology of coastal sequences provides fundamental observations to unravel past sea level (SL) variations. For that purpose, converting morphometric observations into a SL datum requires understanding their morphogenesis. The long-lasting sequence of coral reef terraces (CRTs) at Cape Laundi (Sumba Island, Indonesia) could serve as a benchmark. Yet, it epitomizes a pitfall that challenges the ultimate goal: the overall chronology of its development remains poorly constrained. The polycyclic nature of the terraces, involving marine erosion and reoccupation of old coral colonies by more recent ones hinders any clear assignment of Marine Isotope Stages (MIS) to specific terraces, in particular the reference datum corresponding to the last Interglacial maximum (i.e., MIS 5e). Thus, to overcome these obstacles, we numerically model the genesis of the sequence, testing a range of eustatic SL (ESL) reconstructions and uplift rates, as well as exploring the parameter space to address reef growth, erosion and sedimentation. A total of 625 model runs allowed us to improve the morpho-chronological constraints of the coastal sequence and, more particularly, to explain the morphogenesis of the several CRTs associated with MIS 5e. Our results suggest that the lowermost main terrace was first constructed during the marine transgression of MIS 5e and was later reshaped during the marine regression of MIS 5e, as well as during the MIS 5c and MIS 5a highstands. Finally, we discuss the general morphology of the sequence and the implications it may have on SL reconstructions. At Cape Laundi, as elsewhere, we emphasize the necessity of addressing the development of CRT sequences with a dynamic approach, that is, considering that a CRT is a landform built continuously throughout the history of SL oscillations, and not simply during a singular SL maximum. Careful modelling the morphology of a coral reef terrace (CRT) sequence permits to unravel the past sea level (SL) variations, to better understand the reef bioconstruction formed during transgressions, highstands and regressions, and thus potentially improve SL reconstructions. This article explains the presence of Marine Isotopic Stage (MIS) 5e ages of corals sampled on multiple distinct terraces by retracing the eustatic history of this MIS and by demonstrating that it is not necessary to invoke a double SL peak.image
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Chen, Y., Gueguen, P., Chen, K. H., Lin, C. - J., Ku, C. - S., Huang, W. - G., et al. (2023). Dynamic Characteristics of TAIPEI 101 Skyscraper from Rotational and Translation Seismometers. Bulletin Of The Seismological Society Of America, 113(2), 690–709.
Résumé: Continuous data streams from translational and rotational seismometers installed in TAIPEI 101 enable monitoring of the natural frequencies on different time scales. Using the 2014 seismic data recorded on the 90th floor of this high-rise building and the meteorological data from a weather station located just 1 km away, we explored the characteristics and controlling factors of the ambient vibrations in TAIPEI 101. Using the random decrement technique, the three modal frequencies in translation were identified as 0.15 Hz (F1), 0.43 Hz (F2), and 0.78 Hz (F3). For rotation around the vertical axis, the modal frequencies were 0.23 Hz (R1), 0.59 Hz (R2), and 0.93 Hz (R3). In translation, TAIPEI 101 exhibits a trend of increasing modal frequency with increasing temperature but decreasing modal frequency with increasing wind velocity. The trend with temperature is reversed in rotation motion. The different frequency versus temperature relationship seen for rotational and translational motion demonstrates the importance of introducing rotational motion analysis into structural health monitoring. The change in modal frequencies were also found to decrease with growing amplitude. It is intriguing that F1 exhibits a weaker dependency with amplitude with respect to the higher modes, which may be associated with the suppression of F1 vibration caused by the damper installed in TAIPEI 101. Other than long-term (seasonable) variation, we also highlight the hourly variation of the first-mode amplitude throughout a day by comparing with weather and mobility data. Other than the atmospheric conditions that strongly influence the modal frequencies in long-term behavior, we found that human activities may play an important role in the short-term vibration characteristics of the building.
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Chlieh, M. (2023). Triggers of Chile's mega-earthquakes. Nature Geoscience, .
Résumé: Megathrust earthquakes along subduction zones present significant hazards. Evidence from the South Chile subduction zone suggests that the structure and fluid distribution of the megathrust interface governs the size and timing of large earthquakes.
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Chmiel, M., Walter, F., Pralong, A., Preiswerk, L., Funk, M., Meier, L., et al. (2023). Seismic Constraints on Damage Growth Within an Unstable Hanging Glacier. Geophysical Research Letters, 50(9).
Résumé: Forecasting hanging glacier instabilities remain challenging as sensing technology focusing on the ice surface fails to detect englacial damage leading to large-scale failure. Here, we combine icequake cluster analysis with coda wave interferometry constraining damage growth on Switzerland's Eiger hanging glacier before a 15,000 m(3) break-off event. The method focuses on icequake migration within clusters rather than previously proposed “event counting.” Results show that one cluster originated from the glacier front and migrated by 13.9(+/- 1.2) m within 5 weeks before the break-off event. The corresponding crevasse extension separates unstable and stable ice masses. We use the measured source displacement for damage parametrization and find a 90% agreement between an analytical model based on damage mechanics and frontal flow velocities measured with an interferometric radar. Our analysis provides observational constraints for damage growth, which to date is primarily a theoretical concept for modeling englacial fractures.
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Clesi, V., & Deguen, R. (2023). Linking the Core Heat Content to Earth's Accretion History. Geochemistry Geophysics Geosystems, 24(5).
Résumé: In this study we use a parameterized model of differentiation in a magma ocean setting, in which the magma ocean depth evolves during accretion, to predict the composition of the primordial core. We couple this chemical model to a thermal evolution model of the accreting metal to estimate the Earth's core heat content at the end of its formation. We find geochemically consistent models. All these scenarios have in common two key features: (a) the average pressure of metal-silicates equilibration is between 20 and 45 GPa (final pressure between 40% and 60% of CMB pressure); (b) 60%-80% of Earth's mass is accreted as reduced material. The chemical stratification is stable in most cases, though some scenarios result in an unstable compositional stratification. Mixing an initially stratified core requires a small fraction of the energy released after a giant impact. Importantly, the temperature at the Core Mantle Boundary is ranging from 3925 to 4150 K. For example, scenarios in which the magma ocean remains shallow for a large part of the accretion, then gets deeper at the end of accretion can produce chemically coherent models with cooler cores. This suggests that independent constraints on the core temperature could in principle be used as constraints for the differentiation conditions, and core composition. In particular, we find that the abundance of light elements in the core correlates positively with the temperature of the core at the end of accretion, as well as with the average pressure of equilibration during differentiation.
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Cloetingh, S., Sternai, P., Koptev, A., Ehlers, T. A., Gerya, T., Kovacs, I., et al. (2023). Coupled surface to deep Earth processes: Perspectives from TOPO-EUROPE with an emphasis on climate- and energy-related societal challenges. Global And Planetary Change, 226.
Résumé: Understanding the interactions between surface and deep Earth processes is important for research in many diverse scientific areas including climate, environment, energy, georesources and biosphere. The TOPO-EUROPE initiative of the International Lithosphere Program serves as a pan-European platform for integrated surface and deep Earth sciences, synergizing observational studies of the Earth structure and fluxes on all spatial and tem-poral scales with modelling of Earth processes. This review provides a survey of scientific developments in our quantitative understanding of coupled surface-deep Earth processes achieved through TOPO-EUROPE. The most notable innovations include (1) a process-based understanding of the connection of upper mantle dynamics and absolute plate motion frames; (2) integrated models for sediment source-to-sink dynamics, demonstrating the importance of mass transfer from mountains to basins and from basin to basin; (3) demonstration of the key role of polyphase evolution of sedimentary basins, the impact of pre-rift and pre-orogenic structures, and the evo-lution of subsequent lithosphere and landscape dynamics; (4) improved conceptual understanding of the tem-poral evolution from back-arc extension to tectonic inversion and onset of subduction; (5) models to explain the integrated strength of Europe's lithosphere; (6) concepts governing the interplay between thermal upper mantle processes and stress-induced intraplate deformation; (7) constraints on the record of vertical motions from high -resolution data sets obtained from geo-thermochronology for Europe's topographic evolution; (8) recognition and quantifications of the forcing by erosional and/or glacial-interglacial surface mass transfer on the regional magmatism, with major implications for our understanding of the carbon cycle on geological timescales and the emerging field of biogeodynamics; and (9) the transfer of insights obtained on the coupling of deep Earth and surface processes to the domain of geothermal energy exploration.Concerning the future research agenda of TOPO-EUROPE, we also discuss the rich potential for further ad-vances, multidisciplinary research and community building across many scientific frontiers, including research on the biosphere, climate and energy. These will focus on obtaining a better insight into the initiation and evolution of subduction systems, the role of mantle plumes in continental rifting and (super)continent break-up, and the deformation and tectonic reactivation of cratons; the interaction between geodynamic, surface and climate processes, such as interactions between glaciation, sea level change and deep Earth processes; the sensitivity, tipping points, and spatio-temporal evolution of the interactions between climate and tectonics as well as the role of rock melting and outgassing in affecting such interactions; the emerging field of bio-geodynamics, that is the impact of coupled deep Earth – surface processes on the evolution of life on Earth; and tightening the connection between societal challenges regarding renewable georesources, climate change, nat-ural geohazards, and novel process-understanding of the Earth system.
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Cornet, A., Garbarino, G., Zontone, F., Chushkin, Y., Jacobs, J., Pineda, E., et al. (2023). Denser glasses relax faster: Enhanced atomic mobility and anomalous particle displacement under<i> in</i><i>-situ</i> high pressure compression of metallic glasses. Acta Materialia, 255.
Résumé: Despite that metallic glasses are among the most studied metallic materials, still very little is known on the evolution of their unique structural, dynamical and elastic properties under compression, owing to the difficulty to perform in-situ high pressure experiments. Coupling the brightest x-rays available in synchrotrons with cutting edge high pressure technologies, we provide direct evidence of the microscopic structural and dynamical mechanisms occurring under in-situ high pressure compression and decompression in the GPa range, from the onset of the perturbation up to a severely-deformed state. We show that while pressure promotes density increasing through quasi-elastic structural deformations, the atomic mobility exhibits a hysteresis and is enhanced up to a factor 15 even at temperatures well below the glass transition. This surprising behavior results from a competition between fast avalanche-like atomic rearrangements and slow relaxation processes triggered by an anomalous super-diffusive collective particle displacement. These results provide new insights on the effect of deformation in non-ergodic materials and support the occurrence of string-like diffusion of liquid-like atoms in metallic glasses. They explain also the macroscopic impressive rejuvenation and strain hardening reported recently under ex-situ densifications.
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Corre, M., Brunet, F., Schwartz, S., Gautheron, C., Agranier, A., & Lesimple, S. (2023). Quaternary low-temperature serpentinization and carbonation in the New Caledonia ophiolite. Scientific Reports, 13(1).
Résumé: The low-temperature alteration (< 150 degrees C) of ophiolites by infiltrated meteoric waters removes atmospheric CO2 through mineral carbonation and is assumed to generate H-2 and possibly CH4 according to so-called serpentinization reactions. This overall alteration pattern is primarily constrained by the chemical composition of alkaline springs that are issued in several ophiolites worldwide. Here we report on the fingerprint, as veinlet mineralization, of the reactive percolation of such meteoric waters in the New Caledonia ophiolite (Massif du Sud). The mineralization which resulted from carbonation and serpentinization reactions, is young (< 2 Ma) and formed at a temperature of ca. 95 degrees C. It is mainly composed of lizardite, dolomite, magnetite +/- pyroaurite. Thermochemical simulation of mineral-water equilibria shows that the percolating aqueous fluid was alkaline and H-2 bearing. The delta C-13 of dolomite is exceptionally high, between 7.1 and up to 17.3 parts per thousand, and is interpreted as evidence of low-temperature methanogenesis. Overall, the percolating fluid had a chemical composition similar to that of the waters issued today in the (hyper)alkaline springs of the Massif du Sud. The studied veinlets are thus interpreted as a sample of the plumbing system that fed an ancient Quaternary alkaline spring in the area.
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Cossa, D., Guedron, S., Coquery, M., Calafat, A., Zuniga, D., Stavrakakis, S., et al. (2023). Mercury deposition in the Eastern Mediterranean: Modern fluxes in the water column and Holocene accumulation rates in abyssal sediment. Chemical Geology, 636.
Résumé: Modern and past mercury (Hg) fluxes in the oceanic water column and abyssal sediments are poorly quantified. Here, we investigated the particulate transfer of Hg in the water column of the ultra-oligotrophic Ionian Sea (Eastern Mediterranean) with sediment traps during a one-year period, and its accumulation in the deep central abyssal plain using sediment cores comprising the last 10 ka. The Hg concentrations in the particles collected in the sediment traps varied from 112 to 401 ng g(-1) and enabled quantifying annual Hg fluxes of 2.0, 2.5, and 2.5 μg m(- 2) a(-1), for traps deployed at 250, 1440, and 2820 m deep, respectively. Hg collected in the upper trap originates from atmospheric deposition, including Saharan dust, which is scavenged by the biological pump. Higher Hg fluxes found at mid-depth and near-bottom than in the upper water layer are attributed to lateral advection under the mixed layer of Hg-rich resuspended sediments from the Adriatic continental margin. In the abyssal sediment, Hg concentrations range from 15 to 134 ng g(-1) with the highest levels in the Sapropel S1. Methylmercury concentrations varied from 0.06 to 0.24 ng g(-1) following the distribution of total Hg, with evidence of its specific accumulation at the oxidized front of the sapropel. We estimated that <1.8% of the total Hg in the sedimentary column was diagenetically reallocated. The reconstruction of historical Hg accumulation rates (HgAR) during the Holocene shows low pre-anthropogenic values (similar to 0.3 μg m(2)a(- 1) before 4 ka BP), increasing up to similar to 0.9 μg m(2)a(- 1) during the late Iron Age and the Roman period (1.5-2.5 ka BP), and up to 2.9 μg m(2)a(- 1) during the Industrial Era. During the Sapropel S1 period (similar to 6-10 ka BP), HgARs rose to 6.4 μg m(- 2) a(-1) likely due to the intensity of the Hg removal by the biological pump, the organic matter preservation, along with high inputs of Hg-rich terrigenous matter and a possible restricted recycling in the atmosphere. Hg accumulation in the Ionian Sea deep sediment is found similar to 3-fold lower than those in the western Mediterranean abyssal plain.
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Costantino, G., Giffard-Roisin, S., Radiguet, M., Dalla Mura, M., Marsan, D., & Socquet, A. (2023). Multi-station deep learning on geodetic time series detects slow slip events in Cascadia. Communications Earth & Environment, 4(1).
Résumé: Slow slip events (SSEs) originate from a slow slippage on faults that lasts from a few days to years. A systematic and complete mapping of SSEs is key to characterizing the slip spectrum and understanding its link with coeval seismological signals. Yet, SSE catalogues are sparse and usually remain limited to the largest events, because the deformation transients are often concealed in the noise of the geodetic data. Here we present a multi-station deep learning SSE detector applied blindly to multiple raw (non-post-processed) geodetic time series. Its power lies in an ultra-realistic synthetic training set, and in the combination of convolutional and attention-based neural networks. Applied to real data in Cascadia over the period 2007-2022, it detects 78 SSEs, that compare well to existing independent benchmarks: 87.5% of previously catalogued SSEs are retrieved, each detection falling within a peak of tremor activity. Our method also provides useful proxies on the SSE duration and may help illuminate relationships between tremor chatter and the nucleation of the slow rupture. We find an average day-long time lag between the slow deformation and the tremor chatter both at a global- and local-temporal scale, suggesting that slow slip may drive the rupture of nearby small asperities. A deep learning detector applied to raw multi-station geodetic time series data from 2007 to 2022 is able to identify slow slip events in the Cascadia region and finds that they are each associated with periods of greater tremor activity
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Courtial-Manent, L., Mugnier, J. - L., Zerathe, S., Carcaillet, J., Vassallo, R., Ravanel, L., et al. (2023). Late Holocene initiation of a deep rock slope failure in an alpine valley revealed by 10Be surface exposure dating (Chamonix, France). Quaternary International, 652, 52–62.
Résumé: We studied a newly identified, multiple-kilometer-long rock slope failure in the Aiguilles Rouges massif (Cha-monix valley, France). Owing to a high-resolution light detection and ranging (LiDAR) digital elevation model (DEM) and field work, we mapped morphostructures, including scarps, open fractures, and counterscarps. In some places, vertical offsets can reach tens of meters and crevasses can be meters wide. The evidence of grav-itational activity (boulder displacements from analyses of archival satellite images) and the sharpness of the scarp outcrops together suggest very recent movements. These observations agree with ground displacement rates of a few millimeters per year estimated by interferometric synthetic aperture radar (InSAR) time series between 2014 and 2018.We sampled two vertical profiles along the top scarps to define the chronology of the slope failure using beryllium-10 (10Be) surface exposure dating. Glacially polished surfaces cut by these gravitational scarps were also sampled to determine glacial retreat timing as well as to constrain the pre-exposure 10Be inheritance. In total, 11 samples were studied.Our results highlight a significant time lag (approximately 15 ka) between the first evidence of nonglacial activity and the initiation of the slope failure that happened 1.3-2.5 ka ago, depending on the inheritance schemes. This suggests that the delayed opening of the crevasse is only one stage of a process that began when the valley was deepened and the glacial debuttressing is not the unique driving factor. This process of progressive failure of an excessively steep slope may continue, and the evolution of this slope failure may constitute a hazard for the upper part of the Chamonix valley.
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Daout, S., D'Agostino, N., Pathier, E., Socquet, A., Lave, J., Doin, M. - P., et al. (2023). Along-strike variations of strain partitioning within the Apennines determined from large-scale multi-temporal InSAR analysis. Tectonophysics, 867.
Résumé: In the Apennine Mountains of the Italian Peninsula, GPS data display 3-4 mm/yr of divergent motion oriented N50 degrees E between the Adriatic and Tyrrhenian coastlines. However, the mechanisms driving this extension remain debated and along-strike variations of extension within the actively deforming belt remain poorly constrained. Here, we derived the first large-scale extensional and vertical velocity field for the Apennines by multi-temporal InSAR analysis of 7 years of Sentinel-1 data at the scale of the entire range, improving the spatial resolution and vertical accuracy of existing GPS measurements. The results reveal along-strike variations of extensional rates and gradients, with extension concentrated on single fault systems in the north, consistent with the loci of seismicity and recent moderate earthquakes, and distributed throughout the central Apennines, where the range is widening. Vertical surface displacements do not resolve any active long-wavelength uplift of the orogenic belt and, on average, show more subsidence than uplift relative to the Tyrrhenian and Adriatic coasts. This work provides the first InSAR-based geodetic map of differential extension and uplift within the Italian Peninsula. Our results are compatible with a pure shear extensional model of the crust, driven by both boundary and gravitational forces.
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Darrin, M., Samudre, A., Sahun, M., Atwell, S., Badens, C., Charrier, A., et al. (2023). Classification of red cell dynamics with convolutional and recurrent neural networks: a sickle cell disease case study. Scientific Reports, 13(1).
Résumé: The fraction of red blood cells adopting a specific motion under low shear flow is a promising inexpensive marker for monitoring the clinical status of patients with sickle cell disease. Its high-throughput measurement relies on the video analysis of thousands of cell motions for each blood sample to eliminate a large majority of unreliable samples (out of focus or overlapping cells) and discriminate between tank-treading and flipping motion, characterizing highly and poorly deformable cells respectively. Moreover, these videos are of different durations (from 6 to more than 100 frames). We present a two-stage end-to-end machine learning pipeline able to automatically classify cell motions in videos with a high class imbalance. By extending, comparing, and combining two state-of-the-art methods, a convolutional neural network (CNN) model and a recurrent CNN, we are able to automatically discard 97% of the unreliable cell sequences (first stage) and classify highly and poorly deformable red cell sequences with 97% accuracy and an F1-score of 0.94 (second stage). Dataset and codes are publicly released for the community.
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De Gelder, G., Solihuddin, T., Utami, D. A., Hendrizan, M., Rachmayani, R., Chauveau, D., et al. (2023). Geodynamic control on Pleistocene coral reef development: Insights from northwest Sumba Island (Indonesia). Earth Surface Processes And Landforms, 48(13), 2536–2553.
Résumé: The fossil record of Quaternary reef systems, as expressed in uplifted regions by sequences of stacked terraces, has been extensively used either to understand their morphodynamics or to unravel sea level variations. Yet, because these two aspects are intimately linked, Quaternary reef analysis is often underdetermined because the analysis often focuses on single sequences, along one-dimensional profiles. Here, we take advantage of the lateral variations of coral reef sequences by documenting the morphological variations of the reef sequence on Sumba Island. Near Tambolaka, northwest Sumba, we analysed a reef transect, topography, and associated sedimentological record to obtain a precise coral reef stratigraphy and geomorphic patterns that can be compared with the well-documented eastern counterpart. In Tambolaka, the reef sequence displays four lower layers of bedded chalky limestone units with a weakly cemented sandy matrix, which we attribute to the Middle Miocene to Pliocene Wakabukak formation based on calcareous nannofossils and planktonic foraminifers. The uppermost layer is a calcretized reefal limestone unit with a well-lithified sandy matrix, which we attribute to the Plio-Pleistocene reef sequence of the Kalianga formation. Seven marine terraces imprint the regional morphology, four of which we correlate with Marine Isotope Stage (MIS) 5e, MIS 7e, MIS 9e, and MIS 11c terraces of Cape Laundi, northeast Sumba. When scrutinized at the light of numerical models of reef development, these results indicate that the morphodynamics of reefal sequences is strongly impacted by the tectonic evolution. The geodynamic context sets both the extrinsic conditions of reef development, such as the morphology of the basement and hydrodynamics, and the intrinsic properties, in particular reef growth rate. While the morphodynamic evolution of the sequence is at first-order representative of the interplay between uplift rates and sea level oscillations, the detailed assemblage of the reef units drastically varies along the coastline.
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Delouche, E., & Stehly, L. (2023). Seasonal Seismic Velocity Variations Measured Using Seismic Noise Autocorrelations to Monitor the Dynamic of Aquifers in Greece. Journal Of Geophysical Research-Solid Earth, 128(12).
Résumé: Monitoring groundwater levels in aquifers is crucial for water resources management on a global scale. In Greece, water stress is particularly high due to the expansion of agricultural land, urbanization and tourism, leading to aquifer over-exploitation. In this study, we investigate the possibility of monitoring groundwater reservoirs from seismic velocity changes (delta v/v) measured using noise autocorrelations. The results obtained at short periods (0.5-3 s) indicate that in several regions, seismic wave velocity varies according to an annual cycle mainly controlled by aquifer loading and discharge. We also predict seismic velocity variations from a simple model using precipitation records. In addition, this model provides a proxy for the characteristic time of aquifer discharge rate and allows us to distinguish shallow alluvial aquifers (similar to 100 m) from deep karst systems (similar to 1 km). Finally, we study the effect of water pumping from groundwater reservoirs. To that end, we combine Global Positioning System (GPS), hydraulic heads and velocity variations measurement. The results indicate that confined and unconfined aquifers respond differently. While for unconfined aquifers, pumping water implies an uplift of the surface, we show that for confined aquifers a subsidence occurs, due to the consolidation of the sediments at depth. Being an in-situ and volumetric measurement, the delta v/v is primarily sensitive to the amount of water stored in the entire aquifer system, whereas GPS measurements provide the deformation at the surface induced by both deep sediment compaction and water level variations. These observations show that GPS, hydraulic head, and delta v/v are complementary tools to monitor aquifers. Monitoring the evolution of groundwater resources is an issue for the twenty-first century. The expansion of agricultural land, urbanization and tourism are depleting aquifers. In this study, we propose to monitor groundwater reservoirs from the evolution of seismic wave velocity. The results obtained in Greece indicate that in several regions, the seismic wave velocity varies according to an annual cycle mainly controlled by aquifer loading and discharge. Hence by using continuous seismic noise records it is possible to track the evolution of aquifers over time and to distinguish shallow (similar to 100 m) from deep aquifers (similar to 1 km). Finally, we study the effect of water pumping from groundwater reservoirs. To that end, we combine Global Positioning System surface deformation measurements with seismic velocity variations. The results indicate that confined and unconfined aquifers respond differently. While for unconfined aquifers, pumping water implies an uplift of the surface, we show that for confined aquifers a subsidence occurs, due to the consolidation of the sediments at depth. While for unconfined aquifers, these surface variations are transient, the drainage of confined aquifers due to pumping is permanent. Seismic velocity at short periods are influenced by the hydrologic cycle and the amount of water within aquifersA simple linear model can predict the evolution of seismic wave velocity from precipitationWe show that Global Positioning System measurement, hydraulic heads and velocity variations are complementary tools to monitor aquifers
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Doan, M. - L., Dutilleul, J., & Henry, P. (2023). Effective Porosity Profile at IODP Site C0002 in the Heart of the Nankai Accretionary Prism, and Its Use for Predicting In Situ Seismic Velocities. Geophysical Research Letters, 50(4).
Résumé: Using logging data and samples collected by the four expeditions of the International Ocean Discovery Program NanTroSEIZE drilling campaign that occupied Site C0002 in the Nankai margin located southwest of Japan, we determined effective porosity and sonic velocity profiles down to 3 km below the seafloor in the accretionary prism, above the seismogenic plate interface. We measured cation exchange capacity to differentiate clay-bound water content from effective porosity, which is representative of compaction. The decrease in effective porosity with depth is fitted with a single exponential decay, which suggests hydrostatic conditions for most of the borehole. The Erickson-Jarrard template was adapted to account for the actual clay-bearing nature of the sediments. We used this improved P-wave velocity-effective porosity relationship to fill shipboard data gaps and predict P- and S-wave velocity profiles at Site C0002.
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Dogru, F., Albino, F., & Biggs, J. (2023). Weather model based atmospheric corrections of Sentinel-1 InSAR deformation data at Turkish volcanoes. Geophysical Journal International, 234(1), 280–296.
Résumé: One of the main constraints on the use of satellite radar data for monitoring natural hazards is the existence of atmospheric signals. In particular, volcanic deformation can be difficult to identify because atmospheric phase delays can mask or even mimic ground deformation signals. Eliminating atmospheric signals is particularly crucial for high-relief volcanoes such as Agri, Tendurek, Acigol, Golludag and Hasandag in the Eastern and Central Anatolia. To overcome the atmospheric effects, we use high-resolution ECMWF weather models coupled with an empirical phase-elevation approach for correcting Sentinel-1 interferograms. We apply these methods to two areas of Turkey, the first of which covers three volcanoes in Central Anatolia (Acigol, Golludag, Hasandag) between January 2016 and December 2018 and the second covers two volcanoes in Eastern Anatolia (Agri, Tendurek) between September 2016 and December 2018. The reduction in standard deviation (quality factor) is calculated for both ascending and descending tracks and the atmospheric corrections are found to perform better on descending interferograms in both cases. Then, we use a least-squares approach to produce a time-series. For Central Anatolia, we used 416 ascending and 415 descending interferograms to create 144 and 145 cumulative displacement maps, respectively, and for Eastern Anatolia, we used 390 ascending and 380 descending interferograms to produce 137 and 130 cumulative displacement maps, respectively. We find that the temporal standard deviation before atmospheric corrections ranges between 0.9 and 3.7 cm for the five volcanoes in the region and is consistently higher on ascending track data, which is acquired at the end of the day when solar heating is greatest. Atmospheric correction reduces the standard deviation to 0.5-2.5 cm. Residual signals might be due to the ice-cap at Agri and agriculture near Acigol. We conclude that these volcanoes did not experience significant magmatic deformation during this time period, despite the apparent signals visible in individual uncorrected interferograms. We demonstrate that atmospheric corrections are vital when using InSAR for monitoring the deformation of high-relief volcanoes in arid continental climates such as Turkey.
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Dollet, C., Gueguen, P., & Hernandez, A. (2023). A comprehensive synthetic database of global seismic losses covering the period 1967-2018. Bulletin Of Earthquake Engineering, 21(9), 4265–4288.
Résumé: This work aims to construct a synthetic database of human and economic seismic losses. For weak-to-moderate magnitude and older earthquakes, the catalogs of losses are incomplete, which limits the creation of probabilistic based loss models. Furthermore, the number of earthquakes involving losses has increased in recent years, following a non-stationary Poisson distribution with a rate proportional to the exposed population and GDP. First, this study involved defining a series of empirical models (from definition of magnitude to losses) tested by the likelihood method applied to data from 377 earthquakes with variables related to exposure (exposed population and exposed GDP) and consequences (economic losses, number of fatalities and injuries). For these 377 earthquakes, the spatial variation of the hazard was deduced from USGS ShakeMaps and the social and economic losses evaluated were made stationary by taking into account exposure evolving over time. We then built a synthetic database of seismic losses from the ISC-GEM catalog of epicenters, which is assumed to be complete and homogeneous since 1967 for magnitudes > 5. The combination of the 377 events and the synthetic data indicates that earthquakes of magnitudes [5.5; 6.9] represent 36% of all economic losses, 56% of all fatalities, and 71% of injuries. An occurrence model was then designed to predict the evolution of losses over the next years.
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Donze, F. - V., Tsopela, A., Guglielmi, Y., Henry, P., & Gout, C. (2023). Fluid migration in faulted shale rocks: channeling below active faulting threshold. European Journal Of Environmental And Civil Engineering, 27(8), 2587–2601.
Résumé: During fluid injection tests performed inside the clay-rich Tournemire fault zone, the monitored fault displacement exhibited limited amplitudes whereas a sharp increase of the permeability occurred as the fluid pressure reached a threshold value. The injected fluid channeled through the fractured zone or at the interface between the host rock and the fault core over decameter distances without triggering large irreversible deformation of the fault zone. To assess the underlying hydro-mechanical mechanisms of this sudden increase of permeability, a numerical model was set up to simulate an injection test inside a fracture. When the fluid pressure outweighs the mechanical contribution of the heterogeneities along the fracture planes, the sudden increase of permeability appears. The existence of the channeling process, occurring below a critical fluid pressure at the fracture scale, could explain why it is possible to generate fault leakage inside a non-active fault zone crossing shale rocks. Based on the in-situ and laboratory monitoring, an analytical expression based on TPHM (Two-Part Hooke's Model) can reproduce the stress-dependent permeability evolution. For low values of the effective stress, a simple cubic law formulation does not reproduce correctly the sharp increase of permeability identified once the Fracture Opening Pressure (FOP) is reached.
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Duputel, Z., Ferrazzini, V., Journeau, C., Catherine, P., Kowalski, P., & Peltier, A. (2023). Tracking changes in magma transport from very-long-period seismic signals at Piton de la Fournaise volcano. Earth And Planetary Science Letters, 620.
Résumé: Changes in magma properties and transport geometry can have a direct impact on volcanic activity. However, such variations can be difficult to track during eruptions. We report previously undetected very long-period (VLP) signals at Piton de la Fournaise that can be used to probe changes in magma transport. Source analysis of VLP events during the August-October 2015 eruption indicates a source depth of about 0.9-1.2 km and points to the resonance of the magma dike feeding the eruption. The evolution of the resonance period reveals a shortening of the dike when the magma flux decreases at the end of the eruption. VLP events are actually quite frequent at Piton de la Fournaise: all eruptions analyzed in this study exhibit VLP signals that are indicative of rapid drops in lava discharge. This work encourages the detection of VLP signals to monitor changes in magma flow during volcanic eruptions, and anticipate the corresponding evolution in effusive activity.& COPY; 2023 Elsevier B.V. All rights reserved.
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El Kadri, S., Beauval, C., Brax, M., Bard, P. Y., Vergnolle, M., & Klinger, Y. (2023). A fault-based probabilistic seismic hazard model for Lebanon, controlling parameters and hazard levels. Bulletin Of Earthquake Engineering, 21(7), 3163–3197.
Résumé: The present work develops a comprehensive probabilistic seismic hazard study for Lebanon, a country prone to a high seismic hazard since it is located along the Levant fault system. The historical seismicity has documented devastating earthquakes which have struck this area. Contrarily, the instrumental period is typical of a low-to-moderate seismicity region. The source model built is made of a smoothed seismicity earthquake forecast based on the Lebanese instrumental catalog, combined with a fault model including major and best-characterized faults in the area. Earthquake frequencies on faults are inferred from geological as well as geodetic slip rates. Uncertainties at every step are tracked and a sensitivity study is led to identify which parameters and decisions most influence hazard estimates. The results demonstrate that the choice of the recurrence model, exponential or characteristic, impacts the most the hazard, followed by the uncertainty on the slip rate, on the maximum magnitude that may break faults, and on the minimum magnitude applied to faults. At return periods larger than or equal to 475 years, the hazard in Lebanon is fully controlled by the sources on faults, and the off-fault model has a negligible contribution. We establish a source model logic tree populated with the key parameters, and combine this logic tree with three ground-motion models (GMMs) potentially adapted to the Levant region. A specific study is led in Beirut, located on the hanging-wall of the Mount Lebanon fault to understand where the contributions come from in terms of magnitudes, distances and sources. Running hazard calculations based on the logic tree, distributions of hazard estimates are obtained for selected sites, as well as seismic hazard maps at the scale of the country. Considering the PGA at 475 years of return period, mean hazard values found are larger than 0.3 g for sites within a distance of 20-30 km from the main strand of the Levant Fault, as well as in the coastal region in-between Saida and Tripoli (>= 0.4 g considering the 84th percentile). The study provides detailed information on the hazard levels to expect in Lebanon, with the associated uncertainties, constituting a solid basis that may help taking decisions in the perspective of future updates of the Lebanese building code.
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El Yousfi, Z., Radiguet, M., Rousset, B., Husker, A., Kazachkina, E., & Kostoglodov, V. (2023). Intermittence of transient slow slip in the Mexican subduction zone. Earth And Planetary Science Letters, 620.
Résumé: In the Mexican subduction zone, slow slip events of various duration, from a few days to several months have previously been identified in the regions of Guerrero and Oaxaca. They occur along with microseismicity: low-frequency earthquakes and tectonic tremors. In this study, we analyzed a 10-year long tremor catalog covering multiple SSE cycles, to identify periods of high tremor activity. We then used the temporal information of these tremor bursts to decompose GNSS time series. Surface velocities estimated for tremor and non-tremor periods are then inverted to locate slip rates on the plate interface. Combining the detected microseismicity information and GNSS time series, we show that large slow slip events are made of clusters of short-lasting slip events occurring at tremor times and located updip of the tremor area. This analysis also allowed us to unveil low amplitude transients in between large slow slip events, that last 8 – 9 days, occurring at tremor times and locations, in both Guerrero and Oaxaca regions. Finally, we show that the plate locking amplitude in between short and large slow slip events increases by a factor up to 0.5 at the location of tremors. & COPY; 2023 Elsevier B.V. All rights reserved.
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Eslami, A., Grieco, G., Bussolesi, M., Ichiyama, Y., Lenaz, D., Skogby, H., et al. (2023). Co-occurrence of compositionally variable chromitites in the Sabzevar ophiolite, NE Iran. Lithos, 446.
Résumé: The Sabzevar ophiolite belt consists of a series of thrust-bound massifs that widen in extent to similar to 150 km in NE Iran. The Kuh-Siah harzburgite-dunite massif in the central sector of this belt hosts abundant discontinuous pod-like chromitite deposits. These deposits are characterized by spinels with contrasting and variable compositions, but without any microtextural differences. The chromian spinel in these chromitite bodies displays a wide range of Cr-number (Cr/(Cr + Al)) atomic ratio from 0.50 to 0.77, and reveals a co-occurrence of Al-rich and Cr-rich chromitites within a single ophiolitic massif. Despite these chemical differences, primary spinels from both the high-Al and high-Cr chromitites have similar TiO2 contents, indicating that they formed in a single tectono-magmatic setting. Both high-Al and high-Cr chromitite samples display low to moderate total platinum group element (PGE) abundances (85-537 ppb). Solid phases hosted by Cr-spinel grains in chromitites and their host dunites can be divided into three categories: platinum group minerals (PGM), base-metal minerals (BMM), and silicates. Euhedral quadrangular and round-shaped silicate inclusions consisting of clinopyroxene, orthopyroxene, Na-bearing phlogopite, serpentine and chlorite, are sporadically scattered in the Cr-spinel grains. These inclusions are mainly single crystals and rarely occur as polyphase assemblages. The BMM are mainly euhedral Ni- and Cu-rich sulfides with rare occurrence of pentlandite. The most widespread PGM are crystals of the laurite-erlichmanite series with subordinate malanite, braggite and BM-PGE-rich sulfides. Textural relationships reflect that the PGM are of magmatic origin. The BMM, on the other hand, formed during both magmatic and post-magmatic processes. The occurrence of low-temperature inclusions within Cr-spinel and ferrian Cr-spinel, comprising tremolite, chlorite and serpentine, are interpreted as post-magmatic entrapments of already-formed silicate phases at the time of grain boundary migration. Our petrographic observations and geochemical interpretations reveal that chromitites in the Kuh-Siah peridotite massif formed during multistage melt/fluid-peridotite reaction processes in an extended intra-oceanic arc-forearc setting located between the Turan and Central Iran continental blocks in the Mid to Late Cretaceous. Mossbauer measurements of Fe3+/Sigma Fe ratios of Cr-spinels from the non-oxidized chromitite samples are relatively similar, more or less in the range 0.15-0.20, whereas those from the more oxidized chromitite samples have Fe3+/Sigma Fe ratios in the range 0.28-0.62. Field observations and textural studies suggest that the localized post-magmatic oxidation is linked to dominant hydrous fluids existing in the shear zone.
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Eslami, A., Malvoisin, B., & Brunet, F. (2023). Hydrothermal alteration of chromitite-dunite pairs from the Sabzevar ophiolite (NE Iran): Chemical and nano-textural evolution of Cr-spinel. Lithos, 442.
Résumé: Hydrothermal alteration of chromitite bodies in the form of pods (from a few centimeters to a few tens of meters in thickness) from the central sector of the Sabzevar ophiolite belt (NE Iran) was examined down to the nanoscale. The main Cr-spinel alteration feature corresponds to homogeneous cores (primary Cr-spinel) either rimmed by or locally replaced by heterogeneous domains composed of spinel grains with little or no inclusions / pores. The chemical evolution of spinel in response to hydrothermal alteration is found to follow two distinct chemical trends: (i) in the massive and semi-massive chromitites, the trend consists in the progressive increase of Cr without Fe3+ incorporation; (ii) in serpentinized dunites containing disseminated Cr-spinel grains, the increase in Cr occurs in conjunction with Fe3+ incorporation. These two trends involve a decrease in the spinel Mg/(Mg + Fe2+) ratio. Nanoscale observation using transmission electron microscopy (TEM) shows that porous ferrian Crspinel which are poorer in Al and Mg and richer in Cr and Fe than the primary Cr-spinel, contains relicts of the primary Cr-spinel as well as intercalated platelets of newly formed magnetite and lizardite/chlorite. Automated crystal orientation mapping reveals that the (001) and (111) planes of newly formed lizardite/chlorite and Crspinel/magnetite, respectively, are parallel. The replacement of the primary Cr-spinel by porous ferrian Crspinel and magnetite is found to be isomorphic. The pores, ranging from 2 to 15 μm in size, may act as pathways for the aqueous solutions involved in the serpentinization process, which fed the crystallization of alteration minerals in the pores. The two different compositional trends in chromite grains from massive/semimassive chromitite and hosted in serpentinized dunite are best explained, using mass-balance calculation, by considering the influence of the Cr-spinel/(Cr-spinel+olivine) initial ratio in the rock (XChr) and the dissolution of Mg at a water-to-rock ratio (w/r) above one. In general, at the cm-to-meter scale, Al and Fe exchange between chromitites and their serpentinized dunite envelope was not observed in the central sector of the Sabzevar ophiolite belt; however, such Al and Fe transfer is clearly observed in other parts of this ophiolite belt, where hydrothermal alteration of podiform chromitites produced magnetite ores. Comparatively, the small extend of chromitite alteration observed here, likely reflects the product of lesser fluid-rock interaction with w/r ratio close to one instead of >103 estimated for the magnetite ores based on the magnitude of the Al transfer to their dunite envelope.
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Farge, G., Jaupart, C., Frank, W. B., & Shapiro, N. M. (2023). Along-Strike Segmentation of Seismic Tremor and Its Relationship With the Hydraulic Structure of the Subduction Fault Zone. Journal Of Geophysical Research-Solid Earth, 128(12).
Résumé: Along the strike of subduction zones, tectonic tremor episodicity is segmented on a geologic scale. Here, we study how this segmentation reflects large-scale variations of the structure and conditions of the fault interface where tremor is generated. We try to understand which properties of the hydraulic system of the fault allow elementary tremor sources to synchronize, leading to the emergence of long-period, large-scale episodic activity. We model tremor sources as being associated with rapid openings of low-permeability valves in the fault zone, which channels the upward flow of metamorphic fluids. Valve openings cause pressure transients that allow interaction between sources. In such a system, tremor activity is thus controlled by unsteady fluid circulation. Using numerical simulations of fluid flow, we explore the impact of valve spatial distribution and fluid flux on the emergence of large-scale patterns of tremor activity. We show that when valves are densely distributed and submitted to near-critical input flux, they synchronize and generate more episodic activity. Based on our model, the most periodic and spatially coherent tremor bursts should thus be emitted from segments densely populated with valves, and therefore of lower permeability than less synchronized segments. The collective activity of their valve population is responsible for fluid-pressure cycling at the subduction scale. In the tremor zone of Shikoku, Japan, the most temporally clustered segment coincides with a downgoing seamount chain, suggesting that the segmentation of the fault zone permeability, and hence of tremor activity, could be inherited from the topography of the subducting oceanic plate. In subduction zones, the fault zone controls plate convergence through friction, controlling if, when and where earthquakes occur. At depths larger than about 40 km, deformation in the fault vicinity transitions to a more stable, ductile regime. At those depths, no earthquakes are expected, and noisy, emergent tectonic tremor is detected instead. Geological and geophysical observations link tremor with the unsteady circulation of high-pressure fluid in the fault zone. Tremor could thus help understand how fluid flows along the subduction interface, where it acts to lower the fault strength and may therefore trigger seismic events. Tremor occurs intermittently, in bursts followed by quiet periods. In this study, we investigate the role of fluid circulation processes in generating tremor, and why its activity varies across different regions. In our model, the intermittence of tremor comes from the intermittence of fluid circulation in the fault. We describe how many small parts of the fault zone can interact, and open or close coherently, generating pulses of fluid flow and the observed bursts of tremor. This framework allows to interpret variations of tremor intermittence as a symptom of how strong the flow and how well fluid circulates in different parts of the subduction interface. In subduction zones, the intensity of temporal clustering and the periodicity of tectonic tremor are segmented along-strikeWe use a model of fluid circulation in the fault to show that segmentation of activity can be caused by variation of transport propertiesTremor segmentation aligns with subducting seamounts in Shikoku, Japan, suggestive of the influence of slab topography
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Firsov, I., Jault, D., Gillet, N., Aubert, J., & Mandea, M. (2023). Radial shear in the flow at the Earth's core surface. Geophysical Journal International, 235(3), 2524–2539.
Résumé: The Earth's magnetic field at the core-mantle boundary is the gradient of a harmonic potential function if the mantle is electrically insulating, and the horizontal components of the field can be derived from its radial component in the mantle. Therefore, these components give no further observational information on the core dynamics. However, it can still be envisioned that the horizontal components of the induction equation at Earth's core surface yield further knowledge on the fluid motions at the top of the core independently of the observations. Here, we show that they provide a linear relationship between the surface velocity and the surface shear (strain shear) that depends on the mantle electrical conductivity. This offers a protocol to calculate the surface shear that we validate with synthetics obtained from dynamo simulations in the limit of a weak mantle conductance. First, using numerical simulations with stress-free boundary condition at the core surface, we retrieve the expected relationship between the horizontal flow u(Sigma) and the shear, u(Sigma)=r partial derivative(r)u(Sigma). Next, we investigate simulations with no-slip boundary condition and insulating mantle, and we obtain the same relationship, even though the shear is not imposed as a boundary condition. Finally, we calculate the flow shear at the top of the core from a magnetic field model based on satellite measurements. The application to geophysical data indicates larger values of the surface flow shear than in the synthetic case, suggesting a possible role of the mantle electrical conductivity. The surface flow shear, in the simulations, much differs from the radial shear in the flow, deeper in the core, which is influenced by the mostly quasi-geostrophic geometry. This implies that we cannot rely on the relationship between the flow and the radial shear for quasi-geostrophic motions to exploit the horizontal components of the induction equation and gain further information on the flow at the Earth's core surface.
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Fu, X., Xie, X., Charlet, L., & He, J. (2023). A review on distribution, biogeochemistry of antimony in water and its environmental risk. Journal Of Hydrology, 625.
Résumé: Antimony, the compounds of which exhibit toxicity, finds extensive usage in industrial processes for flame retardants, plastics, batteries, electronic components, and mechanical bearings. Consequently, mining and industrial activities contribute to the continuous migration of antimony into aquatic environments, influencing the Earth's biogeochemical cycle. Given China's status as the primary global exporter of antimony, the country confronts the challenge of water pollution arising from intensive antimony mining operations. This paper focuses on the latest advances in research concerning antimony toxicity, identifies potential sources of antimony water pollution, and explores its migration pathways and biogeochemistry. Moreover, the study provides estimations of antimony quantities in different compartments. Finally, we discuss the prospects for enhancing our comprehension of antimony's biogeochemical behavior.
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Gastineau, R., Sabatier, P., Fabbri, S. C., Anselmetti, F. S., Roeser, P., Findling, N., et al. (2023). Lateral variations in the signature of earthquake-generated deposits in Lake Iznik, NW Turkey. Depositional Record, .
Résumé: Using lake-sediment cores to document past seismicity requires a comprehensive understanding of possible lateral variations in depositional processes. This study aims to reveal the lateral variations in earthquake-induced event deposits throughout Lake Iznik, a large lake located on the middle strand of the North Anatolian Fault. Based on stratigraphic, sedimentological and geochemical analyses of 14 sediment cores from two subbasins across the lake, five different types of event deposits (T1-T5) were identified and characterised. One event deposit type (T5) is restricted to a delta mouth, characterised by the occurrence of authigenic Fe-Mn carbonates and interpreted to result from flood events. The four other types of event deposits are characterised by their synchronicity between cores and their age consistency with historical earthquakes and are interpreted to be likely generated by earthquakes. The locally prominent 1065 CE historical earthquake that ruptured the sub-lacustrine Iznik Fault produced at least three different types of event deposits. One deposit type (T2) is only observed for this very local earthquake, implying that the type of event deposit might also depend on ground-motion parameters. At the lake scale, the occurrence of various event deposits depends on the flow distance from the source of sediment destabilisations to the coring site.
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Geffroy, T., Guillaume, B., Simoes, M., Replumaz, A., Lacassin, R., Husson, L., et al. (2023). Role of Mantle Drag on the Tectonics of Subduction Zones: Insights From Laboratory Models. Tectonics, 42(12).
Résumé: Along convergent boundaries, the role played by mantle drag remains poorly understood despite its potential impact on subduction dynamics and in turn on the deformation regime of the overriding plate. In this study, we present 11 three-dimensional analog models of subduction including an overriding plate, in which mantle drag at the base of the lower or upper plate results from an imposed unidirectional horizontal mantle flow perpendicular to the trench, and in which the plate opposite to the flow is fixed. We varied the direction and the velocity of the imposed horizontal mantle flow between 0 and 10 cm/yr to quantify its impact on horizontal and vertical upper plate deformation, velocities of plates and subduction, and slab geometry. In our experiments, we show that a mantle flow lower than 5 cm/yr tends to laterally translate the slab rather than to generate internal deformation, resulting in limited differences in slab geometries between models. We also show that plate velocity correlates linearly with the imposed mantle flow velocity and associated mantle drag. The upper plate most often deforms by trench-orthogonal shortening, with shortening rates increasing linearly with mantle flow. Shortening rates are higher when mantle flow is directed toward the fixed upper plate and when the slab has not yet reached the upper-lower mantle discontinuity. Minimum trench-orthogonal shortening rates of 2.5 x 10-15 s-1 are required to thicken upper plates. This study suggests that mantle drag can exert first-order controls on the dynamics of subduction zones and associated tectonics. The convective mantle and lithospheres interact to produce the motion of lithospheric plates at the Earth's surface. However, the time-evolution of their interactions remains to be fully characterized, particularly at subduction zones. Using three dimensional analog models, we test the role of mantle tractions on subduction dynamics by controlling the flow in the upper mantle. In our experiments, we show that the direction of the mantle flow has an impact on the deformation rates observed in the overriding plate, with faster deformation for a mantle flow directed toward the upper plate. The magnitude of the mantle flow also has an impact on the deformation of the overriding plate, with a linear increase of deformation rates with increasing mantle flow velocities. The arrival of the subducting plate at the upper-lower mantle discontinuity induces changes in the force equilibrium that leads to a decrease in plate velocity and upper plate deformation rates. From there, we propose that mantle drag is a key element controlling the time-evolution of subduction zones dynamics and the regime of deformation of the overriding plate. Our models show that mantle drag may exert a first-order control on subduction dynamics and upper plate tectonicsPlate motion and overriding plate deformation linearly increases with the imposed mantle flow velocity in the modelsMantle flow directed toward the trench favors upper plate trench-orthogonal shortening
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Giammarinaro, B., Tsarsitalidou, C., Hillers, G., de Rosny, J., Seydoux, L., Catheline, S., et al. (2023). Seismic surface wave focal spot imaging: numerical resolution experiments. Geophysical Journal International, 232(1), 201–222.
Résumé: Numerical experiments of seismic wave propagation in a laterally homogeneous layered medium explore subsurface imaging at subwavelength distances for dense seismic arrays. We choose a time-reversal approach to simulate fundamental mode Rayleigh surface wavefields that are equivalent to the cross-correlation results of three-component ambient seismic field records. We demonstrate that the synthesized 2-D spatial autocorrelation fields in the time domain support local or so-called focal spot imaging. Systematic tests involving clean isotropic surface wavefields but also interfering body wave components and anisotropic incidence assess the accuracy of the phase velocity and dispersion estimates obtained from focal spot properties. The results suggest that data collected within half a wavelength around the origin is usually sufficient to constrain the used Bessel functions models. Generally, the cleaner the surface wavefield the smaller the fitting distances that can be used to accurately estimate the local Rayleigh wave speed. Using models based on isotropic surface wave propagation we find that phase velocity estimates from vertical-radial component data are less biased by P-wave energy compared to estimates obtained from vertical-vertical component data, that even strong anisotropic surface wave incidence yields phase velocity estimates with an accuracy of 1 per cent or better, and that dispersion can be studied in the presence of noise. Estimates using a model to resolve potential medium anisotropy are significantly biased by anisotropic surface wave incidence. The overall accurate results obtained from near-field measurements using isotropic medium assumptions imply that dense array seismic Rayleigh wave focal spot imaging can increase the depth sensitivity compared to ambient noise surface wave tomography. The analogy to elastography focal spot medical imaging implies that a high station density and clean surface wavefields support subwavelength resolution of lateral medium variations.
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Girault, I., Basile, C., Bernet, M., Paquette, J. - L., Heuret, A., Loncke, L., et al. (2023). Thermochronology and U-Pb dating of detrital zircons from the Demerara Plateau (French Guiana-Suriname): Implications for the provenance of the Early Cretaceous syn-rift sedimentation. Basin Research, 35(4), 1386–1406.
Résumé: The provenance of Early Cretaceous sandstones dredged on the northern margin of the Demerara Plateau, offshore French Guiana and Suriname, reveals the sediment routing system that prevailed through the Equatorial Atlantic rifting. Fission-track analysis and U-Pb dating of 310 and 111 detrital zircons, respectively, have been performed. Microfacies analysis and inherited cooling ages suggest that the sandstones were deposited in shallow marine environments during the Early Cretaceous, before the Late Albian drowning of the marginal plateau. Most of the U-Pb zircon crystallisation ages are comprised of between 700 and 600 Ma and are attributed to the Pan-African-Brasiliano orogeny. Statistical and chronological evidence suggest that the zircon fission-track cooling ages were inherited from source materials. Triassic peak ages (>50% of the population) are attributed to the early phase of Central Atlantic rifting. One sample records a cooling phase at ca. 170 Ma, presumably following volcanic hotspot activity and the opening of the Central Atlantic Ocean. Two other samples record the rapid exhumation of the French Guiana transform margin during the Equatorial Atlantic rifting (127 +/- 11 and 106 +/- 8 Ma). We propose a source-to-sink model in which the Pan-African-Brasiliano basement of the margin was eroded as a result of flexural uplift along the French Guiana margin, and the detrital material funnelled in the Cacipore graben sustained the Early Cretaceous syn-rift sedimentation on the marginal plateau.
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Gisselbrecht, L., Froment, B., Boue, P., & Gelis, C. (2023). Insights into the conditions of application of noise-based spectral ratios in a highly industrialized area: a case study in the French Rhone Valley. Geophysical Journal International, 234(2), 985–997.
Résumé: The local ground motion amplification related to the geology at a specific site (i.e. the so-called site effects) may be classically quantified through the SSR (standard spectral ratio) technique applied on earthquake recordings. However, such a quantification might be challenging to carry out in low-to-moderate seismicity regions. Methods based on background ambient noise, such as noise-based standard spectral ratio (SSRn), might be of great interest in these areas. But noise-derived amplification is particularly sensitive to local anthropogenic sources, which may introduce biases in the evaluation of site effects by dominating the geological effects, especially for frequencies higher than 1 Hz. A hybrid approach (SSRh), developed to reduce biases in noise-based spectral ratios by combining classical earthquake-based spectral ratio (SSR) and SSRn, was recently introduced and relies on a site reference. We here investigate the applicability of SSRn and SSRh in a heavily industrialized environment in the Tricastin Valley (south-east France), where critical facilities are located. We continuously recorded ambient noise from 2020 February to March on a 400-sensor seismic array covering an area of about 10 km by 10 km. We demonstrate that SSRn and SSRh computed below 1 Hz are able to reproduce amplification factors provided by SSR. By contrast, at frequencies higher than 1 Hz, SSRn strongly deviates from SSR. SSRh shows closer results to SSR but presents a dependence to the choice of the local site reference, thereby questioning the possibility to use SSRh blindly to estimate the local amplification in our context. These discrepancies reflect the impact of local anthropogenic sources. We therefore introduced a two-step workflow to mitigate the influence of local sources. The first step is to define a characteristic time window to optimally isolate significant transient signals. The second step consists in selecting the time segments that do not contain these transients with a clustering-based approach. By applying this workflow, we were able to remove some strong anthropogenic transient signals likely to be generated by local sources at some sites and therefore to locally improve the amplification assessment through noise-based spectral ratios. However, stationary sources, whose impact cannot be removed through our procedure, remain a major issue. This study provides some insights into the application of SSRn and SSRh in noisy industrialized areas, especially regarding the impact of local noise sources. It illustrates the difficulty of having a procedure for mitigating the impact of these sources that is efficient everywhere inside such a complex anthropized environment, where different types of sources (including stationary sources) cohabit.
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Gonzalez-Vidal, D., Moreno, M., Sippl, C., Baez, J. C., Ortega-Culaciati, F., Lange, D., et al. (2023). Relation Between Oceanic Plate Structure, Patterns of Interplate Locking and Microseismicity in the 1922 Atacama Seismic Gap. Geophysical Research Letters, 50(15).
Résumé: We deployed a dense geodetic and seismological network in the Atacama seismic gap in Chile. We derive a microseismicity catalog of >30,000 events, time series from 70 GNSS stations, and utilize a transdimensional Bayesian inversion to estimate interplate locking. We identify two highly locked regions of different sizes whose geometries appear to control seismicity patterns. Interface seismicity concentrates beneath the coastline, just downdip of the highest locking. A region with lower locking (27.5 & DEG;S-27.7 & DEG;S) coincides with higher seismicity levels, a high number of repeating earthquakes and events extending toward the trench. This area is situated where the Copiapo Ridge is subducted and has shown previous indications of both seismic and aseismic slip, including an earthquake sequence in 2020. While these findings suggest that the structure of the downgoing oceanic plate prescribes patterns of interplate locking and seismicity, we note that the Taltal Ridge further north lacks a similar signature.
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Goussin, F., Guillot, S., Ruffet, G., Poujol, M., Oliot, E., Replumaz, A., et al. (2023). Polarity and Timing of the Deformation Along the Jinsha Suture Zone (Yushu Area, Northeastern Tibet). Tectonics, 42(12).
Résumé: The Tibetan Plateau was formed by intense Cenozoic shortening (up to 1,100 km) of a composite “proto-Tibet,” itself the product of a long Paleozoic and Mesozoic history of accretion of Gondwana-derived continental fragments and volcanic arcs against the Asian continental margin. The difficult access and the scarcity of outcrops have long limited the possibilities of studying these Mesozoic suture zones in the heart of the Plateau. In this work, we present new U-Pb and 40Ar/39Ar ages from the highly deformed units of the Yushu melange, along the Jinsha Suture in the northeastern Qiangtang terrane. Early Triassic (c. 253 Ma) to Middle Jurassic ages (c. 165 Ma) complement the existing data set and help to refine the chronology of the Paleo-Tethyan oceanic subductions which have structured the northeastern part of the Qiangtang terrane. The Yushu melange records at least three successive tectono-magmatic events. The opening of a back-arc basin during the northward Paleo-Tethyan subduction along the Longmu Co-Shuanghu Suture during Early to Middle Triassic; then its closure during the southward subduction of the Songpan-Ganze Ocean along the Jinsha Suture in Late Triassic. Finally, a shortening phase related to the continental collision of the Songpan-Ganze and Qiangtang blocks from Late Triassic to Early-Middle Jurassic. No evidence for any high- or mid-temperature Cenozoic reactivation of the Jinsha suture in our study area is recorded.
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Gratier, J. - P., Menegon, L., & Renard, F. (2023). Pressure Solution Grain Boundary Sliding as a Large Strain Mechanism of Superplastic Flow in the Upper Crust. Journal Of Geophysical Research-Solid Earth, 128(4).
Résumé: A mechanism accommodating large strain in superplastic flow with elongation of 100%-300%, is described for fine-grained calcareous shales deformed at temperature of 200-335 degrees C and depths of 5-8 km up to slate schists in the Oisans massif, Western Alps, France. Using electron microscopy techniques on thin sections parallel to the principal finite strain axes, we show that the shape ratios of the slightly elongated grains (1.4-1.6), mainly calcite and quartz, do not match the finite strains recorded by the markers of the deformation (truncated belemnites, folded veins) in the maximum elongation and shortening plane (ratio 6.7) or in the maximum and minimum elongations plane (ratio 2.4). Consequently, a grain boundary sliding mechanism is required to explain the measured large finite strains. The most soluble minerals (quartz, calcite, dolomite, and albite), which represent about 95% of the rock, accommodate deformation by pressure solution grain boundary sliding whereas the least soluble minerals (muscovite, chlorite, Fe-Ti oxides) act as indenters or are passively reoriented. Pressure solution is especially efficient in polymineralic rocks. Soluble minerals, which have been healed together in veins or fossils, are much more resistant to deformation and act as rigid objects. Models with idealized tessellation of hexagonal grains and creep laws derived from pressure solution indentation experiments provide deformation maps. We discuss the main parameters of this ductile deformation in the upper crust (thermodynamic conditions, strain rate, stress, distance of mass transfer) and show possible drastic decrease of mass transfer efficiency with decrease of stress and strain rate.
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Gremion, S., Pinel, V., Shreve, T., Beauducel, F., Putra, R., Solikhin, A., et al. (2023). Tracking the evolution of the summit lava dome of Merapi volcano between 2018 and 2019 using DEMs derived from TanDEM-X and Pleiades data. Journal Of Volcanology And Geothermal Research, 433.
Résumé: At andesitic volcanoes, effusive lava flows and dome emplacement alternate with explosive, sometimes very destructive events. It is thus crucial to obtain quantitative information on the dome volume emplaced as well as on the extrusion rate. However, steep slopes and continuous activity make it difficult to install field instruments near many volcano summits. In this study, we take advantage of two high resolution remote-sensing datasets, Pleiades (optical acquisitions in tri-stereo mode) and TanDEM-X (radar acquisitions in bistatic mode), to produce twenty Digital Elevation Models (DEMs) over the summit area of Merapi volcano, Indonesia, between July 2018 and December 2019. We calculate the difference in elevation between each DEM and a reference DEM derived from Pleiades images acquired in 2013, in order to track the evolution of the dome in the crater. Uncertainties are quantified for each dataset by a statistical analysis of areas with no change in elevation. We show that the DEMs derived from Pleiades and TanDEM-X data are consistent with each other and provide good spatiotemporal constraints on the evolution of the dome. Furthermore, the remote-sensing estimate of the lava volume is consistent with local drone measurements carried out by BPPTKG at the time of dome growth. From our DEMs, we show that the dome growth was sustained by a relatively small effusion rate of about 0.0336 +/- 0.0067 m(3).s(-1)(2900 +/- 580 m(3)/day) from August 2018 to February 2019, when it reached a height of 40 m (+/- 5 m) and a volume of 0.64 Mm(3) (+/- 0.03 Mm(3)). The lava dome initially grew radially, and then extended asymmetrically to the northwest and southeast starting in October 2018. From February 2019 onwards, the dome elevation remained constant, but lava was continuously emitted. Lava supply was balanced by destabilization southwards downhill producing an accumulation zone of 400 m long and maximum 15 m (+/- 5 m) high with a volume of 0.37 Mm(3) (+/- 0.29 Mm(3)). The measured accumulation rate between February and September 2019 is 0.0094 +/- 0.001 m(3).s(-1)(810 +/- 90 m(3)/day). In late 2019, several minor explosions partially destroyed the center of the dome. This study highlights the strong potential of the joint use of TanDEM-X and Pleiades DEMs to quantitatively monitor domes at andesitic stratovolcanoes.
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Guedron, S., Delaere, C., Fritz, S. C., Tolu, J., Sabatier, P., Devel, A. - L., et al. (2023). Holocene variations in Lake Titicaca water level and their implications for sociopolitical developments in the central Andes. Proceedings Of The National Academy Of Sciences Of The United States Of America, 120(2).
Résumé: Holocene climate in the high tropical Andes was characterized by both gradual and abrupt changes, which disrupted the hydrological cycle and impacted landscapes and societies. High-resolution paleoenvironmental records are essential to contextualize archaeological data and to evaluate the sociopolitical response of ancient societies to environmental variability. Middle-to-Late Holocene water levels in Lake Titicaca were reevaluated through a transfer function model based on measurements of organic carbon stable isotopes, combined with high-resolution profiles of other geochemical variables and paleoshoreline indicators. Our reconstruction indicates that following a prolonged low stand during the Middle Holocene (4000 to 2400 BCE), lake level rose rapidly similar to 15 m by 1800 BCE, and then increased another 3 to 6 m in a series of steps, attain-ing the highest values after similar to 1600 CE. The largest lake-level increases coincided with major sociopolitical changes reported by archaeologists. In particular, at the end of the Formative Period (500 CE), a major lake-level rise inundated large shoreline areas and forced populations to migrate to higher elevation, likely contributing to the emergence of the Tiwanaku culture.
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Gueguen, P., Astorga, A., & Langlais, M. (2023). Amplitude-Frequency Noise Models for Seismic Building Monitoring in a Weak-to-Moderate Seismic Region. Seismological Research Letters, 94(5), 2231–2243.
Résumé: Herein, we discuss amplitude-frequency noise models for high-quality accelerometric monitoring of a civil engineering building and the benefits of seismic building monitoring policies in weak-to-moderate seismic regions. Since 2004, the city hall building in Grenoble (French Alps) has been monitored continuously. First, accelerometric data from one continuous year are used to derive broadband noise models for the bottom and top of the building. The noise models are compared with (1) the noise sensitivity of the high-gain accelerometer installed in the building and low-cost sensor sensitivity models; (2) the typical earthquake response curves given by Clinton and Heaton (2002); and (3) the earthquakes recorded in the Northern Alps. Then, using earthquakes data, this study highlights threshold values for signal-to-noise ratio ( >= 3 or 9 dB) recordings of earthquake as a function of magnitude and distance for weak-to-moderate earthquakes. We present a preliminary cost-benefit analysis of instrumentation for such regions according to seismic hazard and instrumentation quality. For weak-to-moderate seismic regions like Grenoble area, the capability of high-dynamic accelerometers to record low-amplitude ground motions and building responses is confirmed and encouraged to enable high-quality observation of building response over a broad range of frequencies. Bearing in mind that full-scale building test data are of greater interest for improving our understanding of building response than even the most sophisticated models, the recording of weak-to-moderate earthquakes in building must be broadened using high dynamic instruments to obtain more comprehensive and advanced results.
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Guida, C., Ramothe, V., Chappaz, A., Simonnin, P., Rosso, K. M., Ding, R. - R., et al. (2023). Revisiting Selenium Interactions with Pyrite: From Adsorption to Coprecipitation. Acs Earth And Space Chemistry, 8(1), 67–78.
Résumé: Interactions of selenium (Se), a trace element bioessential at low concentrations but highly toxic at high concentrations, with the most abundant sulfide mineral in the earth's crust, namely, pyrite, were investigated over a wide range of time scales from nanoseconds to days. At the nanosecond scale, selenate Se(VI)O-4(2-) adsorption onto the neat pyrite surface is shown by ab initio computations to proceed via the formation of a chemical bond between an oxyanion oxygen atom and a surface Fe atom, weakening the other Se-O bonds and reducing the Se atom oxidation state. At the hour-to-day scale, the adsorption and coprecipitation of selenate Se(VI)O-4(2-) and selenite, Se(IV)O-3(2-), were investigated through wet chemical batch experiments at various pH values at different sulfide concentrations. Selenium removal from solution is slower and weaker for selenate than for selenite. After 24 h, only 10% of selenate, against 60% of selenite (up to 100% in the presence of sulfide), is removed by the pyrite surface. Independently of its original oxidation state, adsorbed Se is completely reduced to elemental trigonal selenium via adsorption, precipitation, or coprecipitation, as shown by XANES spectroscopy. Our EXAFS results, compared to published data on Se-rich pyrite, show a Se to S substitution within the pyrite structure. The reductive coprecipitation mechanism of selenium with pyrite represents valuable new insights for improving our understanding of modern and ancient biogeochemical cycles involving Se. In addition, several industries can benefit from direct applications of our findings, such as water treatment, green technologies, and sustainable mining.
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Guren, M. G., Renard, F., & Noiriel, C. (2023). Dissolution rate variability at carbonate surfaces: 4D X-ray micro-tomography and stochastic modeling investigations. Frontiers In Water, 5.
Résumé: We provide a detailed 3D characterization of the geometry evolution and dissolution rate mapping at the surface of four carbonate samples, namely a calcite spar crystal, two limestone rock fragments, and an aragonite ooid, using time-lapse X-ray micro-tomography during dissolution experiments at pH 4.0. Evaluation of the retreat and mapping of the reaction rates at the whole surface of the samples reveals a large spatial variability in the dissolution rates, reflecting the composition and the specific contributions of the different regions of the samples. While crystal edges and convex topographies record the highest dissolution rates, the retreat is slower for flat surfaces and in topographic lows (i.e., concave areas), suggesting surface-energy related and/or diffusion-limited reactions. Microcrystalline aragonite has the highest rate of dissolution compared to calcite. Surprisingly, rough microcrystalline calcite surface dissolves globally more slowly than the {1014} faces of the calcite spar crystal. The presence of mineral impurities in rocks, through the development of a rough interface that may affect the transport of species across the surface, may explain the slight decrease in reactivity with time. Finally, a macroscopic stochastic model using the set of detachment probabilities at corner, edge, and face (terrace) sites obtained from kinetic Monte Carlo simulations is applied at the spar crystal scale to account for the effect of site coordination onto reactivity. Application of the model to the three other carbonate samples is discussed regarding their geometry and composition. The results suggest that the global dissolution process of carbonate rocks does not reflect only the individual behavior of their forming minerals, but also the geometry of the crystals and the shape of the fluid-mineral interface.
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Harrichhausen, N., Finley, T., Morell, K. D., Regalla, C., Bennett, S. E. K., Leonard, L. J., et al. (2023). Discovery of an Active Forearc Fault in an Urban Region: Holocene Rupture on the XEOLXELEK-Elk Lake Fault, Victoria, British Columbia, Canada. Tectonics, 42(12).
Résumé: Subduction forearcs are subject to seismic hazard from upper plate faults that are often invisible to instrumental monitoring networks. Identifying active faults in forearcs therefore requires integration of geomorphic, geologic, and paleoseismic data. We demonstrate the utility of a combined approach in a densely populated region of Vancouver Island, Canada, by combining remote sensing, historical imagery, field investigations, and shallow geophysical surveys to identify a previously unrecognized active fault, the XEOLXELEK-Elk Lake fault, in the northern Cascadia forearc, similar to 10 km north of the city of Victoria. Lidar-derived digital terrain models and historical air photos show a similar to 2.5-m-high scarp along the surface of a Quaternary drumlinoid ridge. Paleoseismic trenching and electrical resistivity tomography surveys across the scarp reveal a single reverse-slip earthquake produced a fault-propagation fold above a blind southwest-dipping fault. Five geologically plausible chronological models of radiocarbon dated charcoal constrain the likely earthquake age to between 4.7 and 2.3 ka. Fault-propagation fold modeling indicates similar to 3.2 m of reverse slip on a blind, 50 degrees southwest-dipping fault can reproduce the observed deformation. Fault scaling relations suggest a M 6.1-7.6 earthquake with a 13 to 73-km-long surface rupture and 2.3-3.2 m of dip slip may be responsible for the deformation observed in the paleoseismic trench. An earthquake near this magnitude in Greater Victoria could result in major damage, and our results highlight the importance of augmenting instrumental monitoring networks with remote sensing and field studies to identify and characterize active faults in similarily challenging environments. Plain Language Summary Faults occurring in the upper plate above a subduction zone are often located near densely populated coastal areas, but their hazard is often underappreciated due to their low deformation rates. In the northern Cascadia forearc on the west coast of North America, high-resolution topography and geologic mapping show a similar to 2.3-m-high scarp across a similar to 14,000 year-old land surface 10 km north of downtown Victoria, British Columbia, Canada. This newly identified fault, the XEOLXELEK-Elk Lake fault (XELF), crosses Saanich Peninsula within Greater Victoria and poses a hazard to the region's similar to 400,000 inhabitants. Therefore, determining whether it produced recent large earthquakes is important for updating regional earthquake hazard models and increasing earthquake preparedness. To study the earthquake history of the fault, we used shallow geophysical techniques and excavated a trench across the scarp to examine the sedimentary record of deformation. These combined methodologies determined a single large earthquake, of magnitude 6.1-7.6, likely occurred on the XELF between similar to 4,700 and 2,300 years ago. A similar future earthquake on the XELF Lake fault could cause major damage to the Greater Victoria area. Thus, our results can improve future earthquake hazard assessments.
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Herrera, C., Pasten-Araya, F., Cabrera, L., Potin, B., Rivera, E., Ruiz, S., et al. (2023). Rupture properties of the 2020 M<sub>w</sub> 6.8 Calama (northern Chile) intraslab earthquake. Comparison with similar intraslab events in the region. Geophysical Journal International, 232(3), 2070–2079.
Résumé: We study the 2020 M-w 6.8 Calama earthquake sequence that occurred within the subducting oceanic Nazca plate. The main shock is modelled via waveform inversion using a dynamic rupture model, while detection and location techniques are used to better characterize its aftershock sequence. We analyse the local seismotectonic and thermal context of the subducting Nazca plate to understand the trigger mechanism of this earthquake and how it compares with other significant earthquakes in the vicinity. The stress drop and the related dynamic rupture parameters of the Calama main shock are similar to those of the nearby 2007 M-w 6.8 Michilla and 2015M(w) 6.7 Jujuy intraslab earthquakes, which occurred to the west (trenchwards) and to the east (under the backarc) of the Calama earthquake, respectively. The sequences of these three events were located using a 3-D tomographic velocity model. While the Michilla earthquake sequence occurred within the oceanic crust at temperatures of similar to 250 degrees C, the Calama sequence occurred within the upper lithospheric mantle at similar to 350 degrees C and exhibited a smaller aftershock productivity than Michilla. Additionally, the 3-D tomographic model shows intermediate V-P/V-S ratios (1.72-1.76) in the region of the Calama earthquake. This indicates a less hydrated environment that could be responsible for the smaller aftershock productivity of the Calama earthquake.
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Hintzen, R., Werner, W., Hauck, M., Klemd, R., & Fischer, L. A. (2023). Multistage fluorite mineralization in the southern Black Forest, Germany:evidence from rare earth element (REE) geochemistry. European Journal Of Mineralogy, 35(3), 403–426.
Résumé: The Black Forest hosts a wide range of hydrothermal mineralization, including fluorite-barite vein deposits. In a detailed investigation of the Finstergrund and Tannenboden deposits in the Wieden mining district (southern Black Forest), the diversity, geochemical evolution and relative chronology of multistage fluorite precipitation is tracked on the basis of rare earth element (REE) geochemistry, geologic field relationships and crystal zoning. Geochemical discrimination and mathematical lambda coefficients suggest a total of seven fluorite REE groups, at least three distinguishable post-Variscan fluid mobilization events and independent formation histories for the deposits despite their spatial proximity. Fluorite vein mineralization at the Finstergrund deposit evolved over three fluid generations, was derived from gneissic source aquifers and comprises five distinct fluorite REE groups: the first fluid generation is characterized by fluorite precipitation above 200 degrees C (“group III”), below 200 degrees C (“group I”) and after fractional crystallization (“group IV”); the second generation comprises remobilized fluorite (“group II”); and the third generation revealed fluorite precipitation by meteoric water mixing (“group V”). Fluorite vein formation at the Tannenboden deposit is associated with two distinct fluorite REE patterns derived from the same fluid generation: fluorite precipitation above 200 degrees C (“group VII”) and after cooling below 200 degrees C (“group VI”). Its fluid source aquifer lithology best matches migmatites contrary to previous models that suggest either gneissic or granitic aquifer rocks for fluorite vein precipitation in the Black Forest. The decoupled formation history between the deposits is tectonically controlled as suggested by a new genetic model for the Wieden mining district. The model argues for a change in the local fluid percolation network and the termination of hydrothermal activity at the Tannenboden deposit after the first fluid mobilization event. The geochemical evolution of multistage fluorite mineralization, as exemplified by the Tannenboden and Finstergrund deposits in combination with other fluorite mineralizations in the Black Forest, provides unique insights into the lithospheric origin and precipitation behaviour of fluorite by various fluid-rock interaction processes occurring in large hydrothermal systems. The local diversity of REE patterns emphasizes the need for detailed investigations of individual hydrothermal vein deposits.
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Hirose, T., Wang, Q. - Y., Campillo, M., Nakahara, H., Margerin, L., Larose, E., et al. (2023). Time-lapse imaging of seismic scattering property and velocity in the northeastern Japan. Earth And Planetary Science Letters, 619.
Résumé: Investigating spatio-temporal changes in crustal structure is a key to understanding the dynamic processes in the earth's crust associated with large earthquakes and volcanic activities. The dense seismic network in the northeast part of Japan (Tohoku region) allows us to apply seismic interferometry to continuous records of ambient noise data for studying crustal changes related to the 2008 Mw 6.9 Iwate-Miyagi Nairiku earthquake and the 2011 Mw 9.0 Tohoku-oki earthquake. We track changes in both seismic scattering properties and velocities over five years and spatially localize them based on the coda wave decorrelation and travel time sensitivity kernels calculated from the solution of the radiative transfer equation. The 2008 Iwate-Miyagi Nairiku earthquake caused significant changes in both seismic scattering properties and seismic velocities in the vicinity of the epicenter subjected to dynamic or/and static stress perturbations. Changes in scattering properties associated with the 2011 Tohoku-Oki earthquake around some active volcanoes in the Tohoku region are likely related to geofluid migrations triggered by strong vibrations during the large earthquake. The decrease in seismic velocity exists mainly along the eastern coastal region and extends to the central Quaternary volcanic chains under the combined dynamic and static stress changes by the earthquake. The waveform correlation is possibly sensitive to the fluid content and might be a useful indicator of fluid migration in the crust. This is the first comprehensive demonstration and comparison of the spatio-temporal changes of seismic scattering properties and velocities at long-term and regional scales under the influence of two large earthquakes.& COPY; 2023 Elsevier B.V. All rights reserved.
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Hofmann, B. A., Akcar, N., Szidat, S., Valla, P. G., Christl, M., & Vockenhuber, C. (2023). The Twannberg iron meteorite strewn field in the Swiss Jura mountains: insights for Quaternary environmental conditions. Swiss Journal Of Geosciences, 116(1).
Résumé: The similar to 10 km(2) strewn field of the Twannberg type IIG iron meteorite is located in the Swiss Jura Mountains, 30 km northwest of Bern. The strewn field has been mapped by a group of citizen scientists since 2006, yielding more than 2000 meteorite fragments with a total mass of 152.7 kg until the end of 2022. With a terrestrial age of 176 +/- 19 ka and a minimum pre-atmospheric mass of similar to 250 t, the Twannberg meteorite is a local time marker in an area with a poorly-known paleoenvironmental history. The Twannberg strewn field is located just outside of the maximum extent of ice during the Last Glacial Maximum (LGM). On the Mont Sujet, meteorites are size-sorted in a 6-km long section of the primary strewn field (altitude 945-1370 m a.s.l.), indicating a fall direction from east-northeast to west-southwest (azimuth approximately 250 degrees). On the Twannberg plateau and in the Twannbach gorge, meteorites are not size-sorted and occur in a similar to 5.7-km long area associated with till and recent stream sediments (altitude 430-1075 m a.s.l.). The mass distribution of meteorites on the Twannberg plateau demonstrate that these meteorites were not found where they fell but that they must have been transported up to several km by glacier ice flow after the fall. The distribution of meteorites and of glacially transported Alpine clasts on the Mont Sujet and on the Chasseral chain indicates the presence of local ice caps and of an approximately 200-m higher Alpine ice surface with respect to the LGM at the time of fall. This high ice level during MIS 6 (Marine Isotopic Stage 6, 191-130 ka) indicated by the meteorite distribution is consistent with surface exposure ages of 50-144 ka from nearby resting erratic boulders at altitudes of up to 1290 m a.s.l., including the newly dated Jobert boulder (63 ka). These boulders indicate an ice level similar to 400 m higher than during LGM at a time not later than MIS 6. Post-LGM luminescence ages of loess-containing meteorites on the Mont Sujet and C-14 ages of materials associated with meteorite finds indicate relatively young pedoturbation and increased oxidation of meteorites since similar to 7300 cal BP, possibly correlated with deforestation and enhanced erosion resulting from increased human activities since the Neolithic. This study shows that Twannberg meteorites in their palaeoenvironmental context provide valuable information about ice levels and transport directions during MIS 6 and about their interaction with the post-LGM environmental conditions. The unique Twannberg strewn field has the potential to reveal more valuable information.
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Hollender, F., Theodoulidis, N., Mariscal, A., Chaudat, T., Steidl, J., & Roumelioti, Z. (2023). The ?Glass Beads? Coupling Solution for Borehole and Posthole Accelerometers: Shaking Table Tests and Field Retrievability. Seismological Research Letters, 94(2), 925–934.
Résumé: Borehole accelerometers are designed to record strong ground movements at depth. They have become an important complement to surface accelerometers for seismic and earthquake engineering applications. Borehole accelerometers present several imple-mentation challenges, including their coupling with the geological environment. One possible coupling solution is the use of small glass beads, which are placed inside the borehole casing with the purpose of filling in any empty space between the sensor and the casing walls. We carried out a test on a shaking table, over a wide range of peak ground accelerations (PGA from 0.17 to 1.64g), allowing the comparison of the sig-nals between a surface accelerometer and a borehole accelerometer coupled through the glass beads. These tests show that there is almost no difference between the surface and borehole accelerometer signals between 0.5 and 25 Hz, and only very small differences outside this band (0.2-0.5 Hz and 25-80 Hz). Furthermore, experience from multiple ver-tical accelerometric arrays show that an installation using glass beads is “reversible”, that is, 30 yr after the initial installation it can still be possible to easily extract the acceler-ometers for repair or replacement, without any problems or damage to the sensors.
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Hong, H., Ji, K., Hei, H., Wang, C., Liu, C., Zhao, L., et al. (2023). Clay mineral evolution and formation of intermediate phases during pedogenesis on picrite basalt bedrock under temperate conditions (Yunnan, southwestern China). Catena, 220.
Résumé: In order to better understanding clay mineral evolution coupled with geochemical changes during weathering of igneous rocks under temperate conditions, the picrite basalt-derived soil in Dali (South China) was investigated using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope (SEM), and highresolution transmission electron microscopy (HRTEM) methods. Our results show that smectite and mixedlayer clays occur throughout the weathered soil profile, while discrete kaolinite and illite phases are absent in the soil. From saprolite to topsoil, smectite decreases sharply, while mixed-layer kaolinite/smectite (K/S) and illite/smectite (I/S) clays increase markedly. Clay minerals in the saprolite consist of both dioctahedral and trioctahedral species, while those of the middle to upper profile display a uniform dioctahedral structure. I/S phases are characterized by interstratification of 12-angstrom smectite and 10-angstrom illite layers, and K/S phases by interstratification of 12-angstrom smectite and 7-angstrom kaolinite layers, with I/S/K clays containing all three layer types. Kaolinization of smectite occurs at the initial stage of weathering, earlier than that of smectite illitization. Desilication and K-fixation of smectite take place simultaneously during advanced weathering, resulting in formation of illitic and kaolinitic phases continuously throughout the developmental history of the soil. Notably high K concentrations in the weathering profile may be related to K-fixing in the interlayer of illite due to smectite illitization in response to more advanced weathering and pedogenic processes, while the increasing K content in the topsoil may be ascribed to fertilizer in land use and uptake of K by plants from deeper soil horizons. Fe2O3 and TiO2 accumulation in the topsoil is probably mediated by microorganisms.
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Huguet, L., Le Bars, M., & Deguen, R. (2023). A Laboratory Model for Iron Snow in Planetary Cores. Geophysical Research Letters, 50(24).
Résumé: Solidification of the cores of small planets and moons is thought to occur in the “iron snow” regime, in which iron crystals form near the core-mantle boundary and fall until re-melting at greater depth. The resulting buoyancy flux may sustain convection and dynamo action. This regime of crystallization is poorly understood. Here we present the first laboratory experiments designed to model iron snow. We find that solidification happens in a cyclic pattern, with intense solidification bursts separated by crystal-free periods. This is explained by the necessity of reaching a finite amount of supercooling to re-initiate crystallization once the crystals formed earlier have migrated away. When scaled to planetary cores, our results suggest that crystallization and the associated buoyancy flux would be strongly heterogeneous in time and space, which eventually impacts the time variability and geometry of the magnetic field. In small planets or moons with iron core, solidification proceeds from the top down, producing solid iron crystals at the top of the core. These crystals then fall until they melt at deeper depth, where the temperature is larger. By analogy with snow in the atmosphere, this regime is called iron snow. It creates motions in the liquid core and provides energy for generating a magnetic field. However, the key aspects of this regime remain largely unknown. Using analog laboratory experiments, we have found that solidification occurs in a cyclic pattern, with periods of intense crystal formation followed by quiet periods with no crystals. This happens because crystallization needs a certain amount of cooling below the solidification temperature to be triggered, during which all crystals have risen and melted. Applied to planetary cores, it means that the iron snow would be heterogeneous in space and time, with intermittent and localized crystals falling. This would affect the shape and strength of the planet's magnetic field. We have carried out an experimental study of the dynamics of iron snowOur experiments present crystallization cycles, with intense solidification bursts separated by quiet periodsThis cyclic pattern is controlled by thermal diffusion and by the amount of supercooling required for crystallization
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Husband, R. J., Strohm, C., Appel, K., Ball, O. B., Briggs, R., Buchen, J., et al. (2023). A MHz X-ray diffraction set-up for dynamic compression experiments in the diamond anvil cell. Journal Of Synchrotron Radiation, 30, 671–685.
Résumé: An experimental platform for dynamic diamond anvil cell (dDAC) research has been developed at the High Energy Density (HED) Instrument at the European X-ray Free Electron Laser (European XFEL). Advantage was taken of the high repetition rate of the European XFEL (up to 4.5 MHz) to collect pulse-resolved MHz X-ray diffraction data from samples as they are dynamically compressed at intermediate strain rates (<= 10(3) s(-1)), where up to 352 diffraction images can be collected from a single pulse train. The set-up employs piezo-driven dDACs capable of compressing samples in >= 340 μs, compatible with the maximum length of the pulse train (550 μs). Results from rapid compression experiments on a wide range of sample systems with different X-ray scattering powers are presented. A maximum compression rate of 87 TPa s(-1) was observed during the fast compression of Au, while a strain rate of similar to 1100 s(-1) was achieved during the rapid compression of N-2 at 23 TPa s(-1).
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Hutchison, W., Ogilvie, E. R. D., Birhane, Y. G., Barry, P. H., Fischer, T. P., Ballentine, C. J., et al. (2023). Gas Emissions and Subsurface Architecture of Fault-Controlled Geothermal Systems: A Case Study of the North Abaya Geothermal Area. Geochemistry Geophysics Geosystems, 24(4).
Résumé: East Africa hosts significant reserves of untapped geothermal energy. Exploration has focused on geologically young (<1 Ma) silicic calderas, yet there are many sites of geothermal potential where there is no clear link to an active volcano. The origin and architecture of these systems are poorly understood. Here, we combine remote sensing and field observations to investigate a fault-controlled geothermal play located north of Lake Abaya in the Main Ethiopian Rift. Soil gas CO2 and temperature surveys were used to examine permeable pathways and showed elevated values along a similar to 110 m high fault, which marks the western edge of the Abaya graben. Ground temperatures are particularly elevated where multiple intersecting faults form a wedged horst structure. This illustrates that both deep penetrating graben bounding faults and near-surface fault intersections control the ascent of hydrothermal fluids and gases. Total CO2 emissions along the graben fault are similar to 300 t d (-1); a value comparable to the total CO2 emission from silicic caldera volcanoes. Fumarole gases show d(13)C of -6.4%0 to -3.8%0 and air-corrected He-3/He-4 values of 3.84-4.11 R-A, indicating a magmatic source originating from an admixture of upper mantle and crustal helium. Although our model of the North Abaya geothermal system requires a deep intrusive heat source, we find no ground deformation evidence for volcanic unrest or recent volcanism along the graben fault. This represents a key advantage over the active silicic calderas that typically host these resources and suggests that fault-controlled geothermal systems offer viable prospects for geothermal exploration.
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Iskandar, R., Al Tfaily, B., Cornou, C., Bard, P. - Y., Guillier, B., Harb, J., et al. (2023). Estimating urban seismic damages and debris from building-level simulations: application to the city of Beirut, Lebanon. Bulletin Of Earthquake Engineering, 21(13), 5949–5990.
Résumé: The estimation of seismic damages and debris at the urban scale-at a building-by-building level- is challenging for several reasons. First, commonly used methodologies for seismic damage estimation rarely take into account the local site effects, precisely at the building-level. Second, the available methods for debris estimation fail to estimate at the same time the quantity of debris generated per building according to its damage level and the distribution of the debris (extent and height) around buildings. Finally, the lack of comprehensive data on the building stock and the relevant building properties and their taxonomy further increases the complexity of assessing possible earthquake consequences at an urban scale. This paper addresses these challenges and proposes improvements to the assessment of seismic damages and debris from building-level simulations, along with the development of a 3D building model based on satellite images and heterogeneous data. These developments, applied to the city of Beirut, Lebanon, highlight the control of the site effects on the seismic damage's spatial distribution throughout the city and the large volume and extent of debris to be expected in the city for a strong earthquake.
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Iskandar, R., Dugdale, J., Beck, E., & Cornou, C. (2023). Agent-based simulation of seismic crisis including human behavior: application to the city of Beirut, Lebanon. Simulation-Transactions Of The Society For Modeling And Simulation International, .
Résumé: Earthquake simulations at the urban scale usually focus on estimating the damages to the built environment and the consequent losses without fully taking into account human behavior in crisis. Yet, human behavior is a key element for improving crisis disaster management; therefore, it is important to include it in seismic crisis simulations. In this study, an agent-based model for the simulation of pedestrian evacuation during earthquakes at the city scale is developed following an interdisciplinary approach. The model recreates the urban conditions using Geographic Information System (GIS) and a synthetic population, in addition to the earthquake consequences on the urban fabric. Moreover, the model integrates realistic human behaviors calibrated using quantitative survey results. We simulate pedestrian outdoor mobility with the different constraints that affect it such as the topography and the presence of debris. The simulator is applied to the case of Beirut, Lebanon. A what-if approach is adopted to analyze the population's safety in case of earthquakes in Beirut, particularly the open spaces' capacity to provide shelters and the effect of debris and realistic human behaviors on people's safety. The simulation results show that less than 40% of the population is able to arrive at an open space within 15 min after an earthquake. This number is further reduced when some open spaces are locked. Debris and realistic human behaviors significantly delay the arrivals to safe areas and, therefore, should not be neglected in earthquake simulations.
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Istas, M., Gillet, N., Finlay, C. C., Hammer, M. D., & Huder, L. (2023). Transient core surface dynamics from ground and satellite geomagnetic data. Geophysical Journal International, 233(3), 1890–1915.
Résumé: We present an update of the geomagnetic data assimilation tool pygeodyn, use it to analyse ground and satellite-based geomagnetic data sets, and report new findings on the dynamics of the Earth's outer core on interannual to decadal timescales. Our results support the idea that quasi-geostrophic Magneto-Coriolis waves, recently discovered at a period of 7 yr, also operate on both shorter and longer timescales, specifically in period bands centred around 3.5 and 15 yr. We revisit the source of interannual variations in the length of day and argue that both geostrophic torsional Alfven waves and quasi-geostrophic Magneto-Coriolis waves can possibly contribute to spectral lines that have been isolated around 8.5 and 6 yr. A significant improvement to our ensemble Kalman filter algorithm comes from accounting for cross-correlations between variables of the state vector forecast, using the 'Graphical lasso' method to help stabilize the correlation matrices. This allows us to avoid spurious shrinkage of the model uncertainties while (i) conserving important information contained in off-diagonal elements of the forecast covariance matrix, and (ii) considering a limited number of realizations, thus reducing the computational cost. Our updated scheme also permits us to use observations either in the form of Gauss coefficient data or more directly as ground-based and satellite-based virtual observatory series. It is thanks to these advances that we are able to place global constraints on core dynamics even at short periods.
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Itoh, Y., Socquet, A., & Radiguet, M. (2023). Largest Aftershock Nucleation Driven by Afterslip During the 2014 Iquique Sequence. Geophysical Research Letters, 50(24).
Résumé: Various earthquake models predict that aseismic slip modulates the seismic rupture process but actual observations of such seismic-aseismic interaction are scarce. We analyze seismic and aseismic processes during the 2014 Iquique earthquake sequence. High-rate Global Positioning System displacements demonstrate that most of the early afterslip is located downdip of the M 8.1 mainshock and is accompanied by decaying aftershock activity. An intriguing secondary afterslip peak is located similar to 120 km south of the mainshock epicenter. The area of this secondary afterslip peak likely acted as a barrier to the propagating mainshock rupture and delayed the M 7.6 largest aftershock, which occurred 27 hr later. Interevent seismicity in this secondary afterslip area ended with a M 6.1 near the largest aftershock epicenter, kicking the largest aftershock rupture in the same area. Hence, the interevent afterslip likely promoted the largest aftershock nucleation by destabilizing its source area, favoring a rate-dependent cascade-up model. Subduction zone faults host both fast (regular earthquakes, seismic) and slow (aseismic) slip. Simulation models predict that slow slip can affect fast slip processes. We explored such an interaction taking place during the 2014 Iquique earthquake offshore northern Chile using observation data of crustal deformation by Global Positioning System and earthquakes. We discovered that the fast mainshock slip was terminated by a slowly slipping fault zone, which prevented the simultaneous occurrence of the largest aftershock. Furthermore, afterslip, one type of slow slip following the mainshock, helped the occurrence of the largest aftershock 27 hr after the mainshock. Therefore, the sequential occurrence of large earthquakes can be controlled by slowly slipping faults. Global Positioning System captured crustal deformation during 27 hr between the 2014 Iquique mainshock and its largest aftershockThe mainshock and the largest aftershock areas are separated by an aseismic area, likely preventing both from rupturing as a single eventThe largest aftershock nucleation is a mixture of seismicity and decelerating afterslip, favoring a rate-dependent cascade-up model
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Jacob, J. - B., Janots, E., Cordier, C., & Guillot, S. (2023). Discovery of Variscan orogenic peridotites in the Pelvoux Massif (Western Alps, France). Bsgf-Earth Sciences Bulletin, 194.
Résumé: Small bodies of mantle-derived peridotites and other ultramafic rocks are commonly found in exhumed lower crustal units of collisional orogens. They provide a direct record of the complex evolution of the upper mantle before and during an orogeny, and are therefore key markers of the geodynamic evolution of an orogen. We report here the discovery of such mantle-derived peridotites, which occur as fragmented enclaves in migmatites of the high-grade Variscan lower crust exposed in the Pelvoux Massif (external Western Alps). A wide petrographic diversity has been observed, from very fertile, garnet-bearing lherzolites, to more depleted spinel/chromite-bearing harzburgites. Thermobarometric calculations on a garnet lherzolite indicate an initial stage at 3.0-4.0 GPa and 970-1140 degrees C, followed by exhumation to 0.8-1.3 GPa and 800-850 degrees C, while the harzburgites do not show any evidence of equilibration in the garnet field. Petrological observations, whole-rock geochemistry and in situ mineral compositions suggest the peridotites have undergone a complex history prior to their incorporation in the lower crust during the Variscan Orogeny. They derive from a refractory mantle, which has experienced variable degrees of melt depletion, and has then been extensively refertilized. Cryptic metasomatism is observed in all samples. It is characterized by an enrichment in large-ion lithophile elements (LILE, in particular Cs, Rb, U and Pb) relative to high field strength elements (HFSE), in particular Nb and Ta. This cryptic metasomatism is presumably related to percolation of subduction-related fluids or melts in the mantle. In addition, modal metasomatism occurred in some samples, where crystallization of phlogopite, pargasite, chromite and apatite has been observed. This modal metasomatism resulted in significant enrichment in K2O, P2O5 and Cr2O3 of the bulk rock, together with a strong enrichment in incompatible LREE relative to HREE. These geochemical characteristics are strikingly similar to that of syn-collisional, Mg-Cr-LILE rich mantle-derived (ultra)-potassic magmas such as durbachites and vaugnerites, which are ubiquitous in the Variscan metamorphic allochthons of Massif Central, external Alps, Vosges and Bohemian Massif. We therefore suggest that this metasomatism results from dynamic percolation of the peridotites by K2O-P2O5-Cr2O3-rich melts from which the durbachites and vaugnerites are primarily derived. These geochemical characteristics are in line with whole-rock Nd isotopic compositions, which indicate enrichment of the mantle by a continental crust component, presumably related to Variscan subductions. This evolution is consistent with that of other Variscan peridotites in the Eastern Alps (Ulten) and the Bohemian Massif, where multiple metasomatic episodes related to melts or fluids released in Variscan subduction zones have been documented.
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Jacques, P., Delannoy, L., Andrieu, B., Yilmaz, D., Jeanmart, H., & Godin, A. (2023). Assessing the economic consequences of an energy transition through a biophysical stock-flow consistent model. Ecological Economics, 209.
Résumé: The biophysical foundations of socio-economic systems are underrepresented in the vast majority of macroe-conomic models. This lack is particularly troublesome when considering the links between energy, matter and the economy in the context of the energy transition. As a remedy, we present here a biophysical stock-flow consistent macroeconomic model calibrated at the global scale, that combines detailed bottom-up estimates for the high capital intensity of renewable energies and the decreasing energy return on investment (EROI) of fossil fuels. We find that the completion of a global energy transition scenario compatible with the 1.5 degrees C objective of the Paris Agreement leads to a decrease of the system's EROI and to high investment share, employment and inflation trends, characteristic of a “war economy”. Our results further indicate that a slower growth rate eases the transition, and call for further work on post-growth scenarios studies.
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Jafari, M., Aflaki, M., Mousavi, Z., Walpersdorf, A., & Motaghi, K. (2023). Coseismic and post-seismic characteristics of the 2021 Ganaveh earthquake along the Zagros foredeep fault based on InSAR data. Geophysical Journal International, 234(2), 1125–1142.
Résumé: The Ganaveh earthquake on 2021 April 18 (M-w 5.8) occurred in the southwest of the Dezful embayment of the Zagros Mountain belt, Iran, as a mainly compressive event. The InSAR coseismic displacement maps reveal a maximum of 17 cm of surface displacement in the satellite line of sight direction. InSAR inversion indicates a low-angle NE-dipping causative fault plane with a maximum slip of 95 cm at similar to 6 km depth. It highlights the occurrence of the Ganaveh earthquake within the competent layers of the Zagros sedimentary cover, beneath the Gachsaran formation. A slight sinistral slip component (2.9 cm) is retrieved which is compatible with the USGS focal mechanism. Time-series analysis of SAR images after the main shock until the end of 2021 indicates a maximum of 7 cm of post-seismic surface displacement with a similar strike and pattern as the coseismic phase. This similarity and the distribution of aftershocks suggest an afterslip mechanism for the post-seismic phase. The inversion of post-seismic cumulative displacement evaluates a maximum of 30 cm slip at a depth of similar to 5 km along the coseismic causative fault. A regional compressional stress regime (N041 degrees E for the direction of the sigma(1) stress axis) is constrained by using the focal mechanisms of 39 earthquakes occurring between 1968 and 2021, including the Ganaveh main shock and its five larger aftershocks. Applying this direction of compression on the Ganaveh fault plane also results in a minor sinistral movement, consistent with the geodetic results. The relocated main shock and aftershocks as well as our InSAR coseismic displacement situations on the hanging wall of the Zagros Foredeep fault highlight it as the causative fault of the Ganaveh earthquake. To fit the geometry of the Ganaveh rupture plane with the Zagros Foredeep fault, we modelled a listric fault plane and its slip distribution using the available geological data. The retrieved slip variation on the listric plane is in close agreement with the slip pattern on the modelled planar geometry. The low dip angle of the rupture plane combined with a listric geometry highlights the thin-skin characteristics of the Zagros Foredeep fault as the causative fault of the Ganaveh earthquake. The occurrence of this moderate magnitude earthquake on the Zagros Foredeep fault underlines its role as the western structural boundary for the recurrence of M-b > 5 events in the Dezful embayment.
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Jaisle, N., Cebron, D., Konopkova, Z., Husband, R. J., Prescher, C., Cerantola, V., et al. (2023). MHz free electron laser x-ray diffraction and modeling of pulsed laser heated diamond anvil cell. Journal Of Applied Physics, 134(9).
Résumé: A new diamond anvil cell experimental approach has been implemented at the European x-ray Free Electron Laser, combining pulsed laser heating with MHz x-ray diffraction. Here, we use this setup to determine liquidus temperatures under extreme conditions, based on the determination of time-resolved crystallization. The focus is on a Fe-Si-O ternary system, relevant for planetary cores. This time-resolved diagnostic is complemented by a finite-element model, reproducing temporal temperature profiles measured experimentally using streaked optical pyrometry. This model calculates the temperature and strain fields by including (i) pressure and temperature dependencies of material properties, and (ii) the heat-induced thermal stress, including feedback effect on material parameter variations. Making our model more realistic, these improvements are critical as they give 7000 K temperature differences compared to previous models. Laser intensities are determined by seeking minimal deviation between measured and modeled temperatures. Combining models and streak optical pyrometry data extends temperature determination below detection limit. The presented approach can be used to infer the liquidus temperature by the appearance of SiO2 diffraction spots. In addition, temperatures obtained by the model agree with crystallization temperatures reported for Fe-Si alloys. Our model reproduces the planetary relevant experimental conditions, providing temperature, pressure, and volume conditions. Those predictions are then used to determine liquidus temperatures at experimental timescales where chemical migration is limited. This synergy of novel time-resolved experiments and finite-element modeling pushes further the interpretation capabilities in diamond anvil cell experiments.
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Janeras, M., Lantada, N., Nunez-Andres, M. A., Hantz, D., Pedraza, O., Cornejo, R., et al. (2023). Rockfall Magnitude-Frequency Relationship Based on Multi-Source Data from Monitoring and Inventory. Remote Sensing, 15(8).
Résumé: Quantitative hazard analysis of rockfalls is a fundamental tool for sustainable risk management, even more so in places where the preservation of natural heritage and people's safety must find the right balance. The first step consists in determining the magnitude-frequency relationship, which corresponds to the apparently simple question: how big and how often will a rockfall be detached from anywhere in the cliff? However, there is usually only scarce data on past activity from which to derive a quantitative answer. Methods are proposed to optimize the exploitation of multi-source inventories, introducing sampling extent as a main attribute for the analysis. This work explores the maximum possible synergy between data sources as different as traditional inventories of observed events and current remote sensing techniques. Both information sources may converge, providing complementary results in the magnitude-frequency relationship, taking advantage of each strength that overcomes the correspondent weakness. Results allow characterizing rockfall detachment hazardous conditions and reveal many of the underlying conditioning factors, which are analyzed in this paper. High variability of the hazard over time and space has been found, with strong dependencies on influential external factors. Therefore, it will be necessary to give the appropriate reading to the magnitude-frequency scenarios, depending on the application of risk management tools (e.g., hazard zoning, quantitative risk analysis, or actions that bring us closer to its forecast). In this sense, some criteria and proxies for hazard assessment are proposed in the paper.
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Jarrin, P., Nocquet, J. - M., Rolandone, F., Audin, L., Mora-Paez, H., Alvarado, A., et al. (2023). Continental block motion in the Northern Andes from GPS measurements. Geophysical Journal International, 235(2), 1434–1464.
Résumé: Northwestern South America is a plate boundary zone where the Nazca, Caribbean and South American plates interact to produce a wide area of active continental deformation from the Gulf of Guayaquil (latitude 3 & DEG;S) to Venezuela. Previous studies have identified a & SIM;2000-km-long continental sliver, referred as the North Andean Sliver (NAS), squeezed between the Nazca, Caribbean and South American plates and escaping at & SIM;1 cm yr(-1) northeastward with respect to South America. Subduction of the Nazca Plate beneath the NAS has produced a sequence of large and great earthquakes during the 20th century along the coast of Ecuador and Colombia. Large crustal earthquakes up to magnitude 7.7 have been documented along the proposed eastern boundary of the NAS. However, active tectonics data, historical and recent earthquakes all indicate active fault systems within the NAS, possibly resulting from the interaction of several tectonic blocks. Here, we derive an extensive horizontal velocity field using continuous and episodic GNSS data from 1994 to 2019.9, covering northern Peru, Ecuador, Colombia, Panama and Venezuela. We model the GNSS velocity field using a kinematic elastic block approach that simultaneously solves for rigid tectonic block rotations and interseismic coupling along the subduction interfaces and along major crustal faults. In contrast to previous results that considered a single rigid NAS, our dense GNSS velocity field demonstrates that the NAS undergoes significant internal deformation and cannot be modelled as single rigid block. We find that block kinematics in the northern Andes are well described by the rotation of 6 tectonic blocks, showing increasing eastward motion from south to north. The Eastern boundary of the sliver is defined by a right-lateral transpressive fault system accommodating 5.6-17 mm yr(-1) of motion. Fragmentation of the NAS occurs through several fault systems with slip rates of 2-4 mm yr(-1). Slow reverse motion is found across the sub-Andean domain in Ecuador and northern Peru at 2-4 mm yr(-1), marking a transitional area between the NAS and stable South America. In contrast, such a transitional sub-Andean domain does not exist in Colombia and western Venezuela. At the northwestern corner of Colombia, fast (& SIM;15 mm yr(-1)) eastward motion of the Panama block with respect to the NAS results in arc-continent collision. We propose that the Uramita fault and Eastern Panama Deformed Zone define the current Panama/NAS boundary, accommodating 6 and 15 mm yr(-1) of relative motion, respectively. A fraction of the Panama motion appears to transfer northeastward throughout the San Jacinto fold belt and as far east as longitude & SIM;75 & DEG;W. Along the Caribbean coast, our model confirms, slow active subduction at & SIM;4.5 mm yr(-1) along the South Caribbean Deformed Belt offshore northern Colombia and a relatively uniform rate of & SIM;1-2 mm yr(-1) offshore northern Venezuela. Along the Nazca/NAS subduction interface, interseismic coupling shows a first-order correlations between highly locked patches and large past earthquake ruptures. These patches are separated by narrow zones of low/partial coupling where aseismic transients are observed. Compared to previous studies, our interseismic coupling model highlights the presence of deep coupling down to 70 km in Ecuador.
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Jiao, L., Tapponnier, P., Donze, F. - V., Scholtes, L., Gaudemer, Y., & Xu, X. (2023). Discrete Element Modeling of Southeast Asia's 3D Lithospheric Deformation During the Indian Collision. Journal Of Geophysical Research-Solid Earth, 128(1).
Résumé: The Indian collision has deformed the eastern Asian continent in a multifaceted way, uplifting Tibet and surrounding mountains, activating >= 1,000 km-long strike-slip faults, and opening Tertiary rifts and oceanic basins up to approximate to 3,000 km away from the Himalayas. Modeling such broad-scale tectonics has been challenging. While continent-scale, lithospheric deformation appears to have been primarily taken-up by long, narrow, inter-connected shear-zones with large offsets, the contribution of processes such as channel-flow, collapse, delamination, etc horizontal ellipsis has remained contentious. Here, based on increasing (4)G (Geological, Geophysical, Geochronological, Geodetic) evidence including kinematic and timing constraints on the main mechanisms at play, we use Discrete Element (DE) Modeling to simulate and further understand the evolution of 3D strain across east Asia since the onset of collision, approximate to 55 Ma ago. The planar, 50 million km(2), 125 km-thick models are scaled for gravity. The approach permits mega-fault generation and evolution without pre-arranged initial settings. The results provide insight into fault birth, propagation and motion, as well as mountain building and plateau growth. They corroborate that continental crustal thickening across Tibet alternated with the extrusion of large blocks that rifted apart in the far field. Remarkably, without changes in boundary conditions or indentation rate, the DE model also vindicates slip reversal along initial strike-slip shear zones. To better understand the Tertiary, three-dimensional tectonics of South-Eastern Asia, mostly a result of the north-eastwards penetration of “rigid” India since approximate to 55 Ma, we use a Discrete Element Modeling approach. The technique permits the generation and evolution of large faults without initial pre-setting. The model results substantiate the northwards growth of 4/5 Tibet sub-plateaus, atop south-dipping, subducted lithospheric slabs. Two long strike-slip faults, comparable to the Ailao-Shan-Red River and Altyn Tagh-Haiyuan shear zones, successively propagate to the eastern boundary of the model, where they generate extensional basins similar to the South China Sea and North China Rifts. They isolate two stable blocks (approximate to Sunda and South China). Remarkably, without changes in indentation rate, the activation of the northern shear zone triggers slip reversal on the southern one, as observed along Yunnan's Red River faults since the Miocene. On the west side of Sunda, the model generates faults comparable to the Sagaing fault and triangular basins similar to the Andaman and Mergui basins. Finally, the model suggests that crustal thickening across Tibet alternated with strike-slip faulting. The main discrepancy between tectonic observations and model results is the striking difference in strike-slip fault orientation, likely due to age-dependent lithospheric strength.
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Jiao, L., Tapponnier, P., Donze, F. - V., Scholtes, L., Gaudemer, Y., & Xu, X. (2023). Discrete Element Modeling of Southeast Asia's 3D Lithospheric Deformation During the Indian Collision. Journal Of Geophysical Research-Solid Earth, 128(1).
Résumé: The Indian collision has deformed the eastern Asian continent in a multifaceted way, uplifting Tibet and surrounding mountains, activating >= 1,000 km-long strike-slip faults, and opening Tertiary rifts and oceanic basins up to approximate to 3,000 km away from the Himalayas. Modeling such broad-scale tectonics has been challenging. While continent-scale, lithospheric deformation appears to have been primarily taken-up by long, narrow, inter-connected shear-zones with large offsets, the contribution of processes such as channel-flow, collapse, delamination, etc horizontal ellipsis has remained contentious. Here, based on increasing (4)G (Geological, Geophysical, Geochronological, Geodetic) evidence including kinematic and timing constraints on the main mechanisms at play, we use Discrete Element (DE) Modeling to simulate and further understand the evolution of 3D strain across east Asia since the onset of collision, approximate to 55 Ma ago. The planar, 50 million km(2), 125 km-thick models are scaled for gravity. The approach permits mega-fault generation and evolution without pre-arranged initial settings. The results provide insight into fault birth, propagation and motion, as well as mountain building and plateau growth. They corroborate that continental crustal thickening across Tibet alternated with the extrusion of large blocks that rifted apart in the far field. Remarkably, without changes in boundary conditions or indentation rate, the DE model also vindicates slip reversal along initial strike-slip shear zones. To better understand the Tertiary, three-dimensional tectonics of South-Eastern Asia, mostly a result of the north-eastwards penetration of “rigid” India since approximate to 55 Ma, we use a Discrete Element Modeling approach. The technique permits the generation and evolution of large faults without initial pre-setting. The model results substantiate the northwards growth of 4/5 Tibet sub-plateaus, atop south-dipping, subducted lithospheric slabs. Two long strike-slip faults, comparable to the Ailao-Shan-Red River and Altyn Tagh-Haiyuan shear zones, successively propagate to the eastern boundary of the model, where they generate extensional basins similar to the South China Sea and North China Rifts. They isolate two stable blocks (approximate to Sunda and South China). Remarkably, without changes in indentation rate, the activation of the northern shear zone triggers slip reversal on the southern one, as observed along Yunnan's Red River faults since the Miocene. On the west side of Sunda, the model generates faults comparable to the Sagaing fault and triangular basins similar to the Andaman and Mergui basins. Finally, the model suggests that crustal thickening across Tibet alternated with strike-slip faulting. The main discrepancy between tectonic observations and model results is the striking difference in strike-slip fault orientation, likely due to age-dependent lithospheric strength.
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Journeau, C., Shapiro, N. M., Peltier, A., Ferrazzini, V., Soubestre, J., Duputel, Z., et al. (2023). Tracking changes in the co-eruptive seismic tremor associated with magma degassing at Piton de la Fournaise volcano. Journal Of Volcanology And Geothermal Research, 444.
Résumé: Volcanic eruptions in basaltic systems represent the most frequent expression of volcanic activity in the World, whose surface manifestations range from effusive lava flows to more explosive events. Their eruptive dynamics and style are largely controlled by the degassing of magma. In this study, we analyze seismic tremors recorded during 23 eruptions that occurred at Piton de la Fournaise volcano (La Re ' union, France) during 2014-2021 and show that their properties are strongly linked to the magma degassing. We apply the network covariance matrix method to build a catalog of tremor sources associated with all 23 eruptions, to measure their time-frequency properties, and to locate their sources. We then conduct a multi-disciplinary analysis by comparing the seismic tremor observations with images of the eruptive sites, lava flow rate measurements, impulsive earth-quakes, as well as deformation and magma composition data. The tremor depth distribution is found to be well correlated with magma gas content, indicating that the tremor generating mechanism is largely controlled by the shallow magma degassing under the eruptive site. The resulting seismic tremor signals analysis enable to track changes in degassing regimes and associated eruptive styles at the surface, thus improving monitoring and knowledge of the eruptive dynamics of the studied volcano.
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Julia, M., Putnis, C. V., King, H. E., & Renard, F. (2023). Coupled dissolution-precipitation and growth processes on calcite, aragonite, and Carrara marble exposed to cadmium-rich aqueous solutions. Chemical Geology, 621.
Résumé: Calcium carbonate and cadmium-rich fluid interactions have been studied at the nano and microscale with fluid flow and static fluid conditions for three forms of CaCO3: calcite in single crystals of Iceland Spar, calcite in a polycrystalline Carrara marble, and aragonite single crystals. Atomic Force Microscopy (AFM) showed the nanoscale effect of cadmium on CaCO3 dissolution and growth under flow-through conditions at ambient tem-perature, with the modification of calcite dissolution behaviour and simultaneous precipitation of a Cd-rich phase on all the different samples. Hydrothermal experiments at 200 degrees C revealed that the reactivity of single calcite crystals is passivated by epitaxial growth of the less soluble Cd-rich endmember of the (Ca,Cd)CO3 solid -solution on the sample surface due to the similar crystallographic structures of calcite and otavite (CdCO3). Conversely, the presence of grain boundaries in Carrara marble or the change of crystallographic structure and reaction-induced fracturing in aragonite allowed, to some extent, the pseudomorphic replacement of Carrara marble and aragonite samples by a porous (Ca,Cd)CO3 solid-solution phase of variable composition. These phenomena have been observed in solutions undersaturated with respect to all solid phases and are the result of an interface-coupled dissolution-precipitation mechanism where the dissolving CaCO3 provides ions to super-saturate the mineral-fluid interfacial layer, leading to the precipitation of a Cd-containing phase on the samples' surfaces. This coupled dissolution-precipitation mechanism could potentially be used as a remediation process to sequester cadmium from contaminated effluents.
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Karabulut, H., Guevercin, S. E., Hollingsworth, J., & Konca, A. O. E. (2023). Long silence on the East Anatolian Fault Zone (Southern Turkey) ends with devastating double earthquakes (6 February 2023) over a seismic gap: implications for the seismic potential in the Eastern Mediterranean region. Journal Of The Geological Society, 180(3).
Résumé: On 6 February 2023, an earthquake with magnitude M-w c. 7.0 on the Narli Fault, a fault sub-parallel to the East Anatolian Fault Zone (EAFZ), initiated a chain of large earthquakes on the EAFZ. The earthquakes occurred in a seismic gap with low geodetic strain rates and low background seismicity, where deformation is distributed across a wide fault zone and a long recurrence time of historical earthquakes. The c. 50 km long rupture of the Narli Fault towards Pazarcik led to an M-w 7.8 left-lateral strike-slip earthquake breaking a c. 300 km section of the c. 600 km long EAFZ bilaterally with a total duration of more than 80 s. Toward the SW, the rupture propagated on the c. 100 km long Amanos segment with a peak surface offset of 5 m, before diminishing toward the Hatay graben. In the NE direction, the rupture reached a peak surface offset of 7 m before sharply declining at the termination of the 2020 M-w 6.8 Sivrice earthquake rupture. A second large earthquake with M-w 7.6 occurred 9 h later on the Cardak Fault, located at the western margin of (and sub-parallel to) the EAFZ and breaking the surface with almost 9 m of left-lateral slip (average of c. 4 m). Following these large earthquakes, the increase in the regional stress led to a rapid seismic activation in a broad region from central to eastern Anatolia, loading the faults at various scales and increasing seismic hazard. Two weeks after the initiation of the seismic crisis, a third earthquake with M-w 6.4 occurred at the southern boundary of the Hatay graben, near the southwestern termination of the Amanos rupture. The earthquakes caused significant loss of human life, devastating 12 cities. We evaluate the observations prior to the ruptures, and present preliminary seismological results with surface displacements from sub-pixel correlation of optical satellite images and the stress perturbations computed on the nearby faults based on preliminary slip models. The re-evaluation of the seismic potential in light of the recent and historical earthquakes provides some new insight on seismic hazard assessment. The recent series of events on the EAFZ is an important reminder that large faults can generate very large earthquakes on multiple segments. The seismic potential of large earthquakes on these fault zones can be estimated only by considering multiple seismic cycles and moment deficits from very large earthquakes.
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King, G. E., Ahadi, F., Sueoka, S., Herman, F., Anderson, L., Gautheron, C., et al. (2023). Eustatic change modulates exhumation in the Japanese Alps. Geology, 51(2), 131–135.
Résumé: The exhumation of bedrock is controlled by the interplay between tectonics, surface pro-cesses, and climate. The highest exhumation rates of centimeters per year are recorded in zones of highly active tectonic convergence such as the Southern Alps of New Zealand or the Himalayan syntaxes, where high rock uplift rates combine with very active surface processes. Using a combination of different thermochronometric systems including trapped-charge ther-mochronometry, we show that such rates also occur in the Hida Mountain Range, Japanese Alps. Our results imply that centimeter per year rates of exhumation are more common than previously thought. Our thermochronometry data allow the development of time series of exhumation rate changes at the time scale of glacial-interglacial cycles, which show a four-fold increase in baseline rates to rates of -10 mm/yr within the past -65 k.y. This increase in exhumation rate is likely explained by knickpoint propagation due to a combination of very high precipitation rates, climatic change, sea-level fall, range-front faulting, and moderate rock uplift. Our data resolve centimeter-scale sub-Quaternary exhumation rate changes, which show that in regions with horizontal convergence, coupling between climate, surface processes, and tectonics can exert a significant and rapid effect on rates of exhumation.
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La Bella, M., Besselink, R., Wright, J. P., Van Driessche, A. E. S., Fernandez-Martinez, A., & Giacobbe, C. (2023). Hierarchical synchrotron diffraction and imaging study of the calcium sulfate hemihydrate-gypsum transformation. Journal Of Applied Crystallography, 56, 660–672.
Résumé: The mechanism of hydration of calcium sulfate hemihydrate (CaSO4 center dot 0.5H(2)O) to form gypsum (CaSO4 center dot 2H(2)O) was studied by combining scanning 3D X-ray diffraction (s3DXRD) and phase contrast tomography (PCT) to determine in situ the spatial and crystallographic relationship between these two phases. From s3DXRD measurements, the crystallographic structure, orientation and position of the crystalline grains in the sample during the hydration reaction were obtained, while the PCT reconstructions allowed visualization of the 3D shapes of the crystals during the reaction. This multi-scale study unfolds structural and morphological evidence of the dissolution-precipitation process of the gypsum plaster system, providing insights into the reactivity of specific crystallographic facets of the hemihydrate. In this work, epitaxial growth of gypsum crystals on the hemihydrate grains was not observed.
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Labbez, C., Bouzouaid, L., Van Driessche, A. E. S., Ling, W. L., Martinez, J. C., Lothenbach, B., et al. (2023). Mechanisms and kinetics of C-S-H nucleation approaching the spinodal line: Insights into the role of organics additives. Cement And Concrete Research, 173.
Résumé: Wet chemistry C-S-H precipitation experiments were performed under controlled conditions of solution supersaturation in the presence and absence of gluconate and three hexitol molecules. Characterization of the precipitates with SAXS and cryo-TEM experiments confirmed the presence of a multi-step nucleation pathway. Induction times for the formation of the amorphous C-S-H spheroids were determined from light transmittance. Analysis of those data with the classical nucleation theory revealed a significant increase of the kinetic prefactor in the same order as the complexation constants of calcium and silicate with each of the organics. Finally, two distinct precipitation regimes of the C-S-H amorphous precursor were identified: i) a nucleation regime at low saturation indexes (SI) and ii) a spinodal nucleation regime at high SI where the free energy barrier to the phase transition is found to be of the order of the kinetic energy or less.
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Lacroix, P., Huanca, J., Angel, L. A., & Taipe, E. (2023). Precursory Motion and Time-Of-Failure Prediction of the Achoma Landslide, Peru, From High Frequency PlanetScope Satellites. Geophysical Research Letters, 50(19).
Résumé: Landslide time-of-failure prediction is crucial in natural hazards, often requiring precise measurements from in situ instruments. This instrumentation is not always possible, and remote-sensing techniques have been questioned for detecting precursors and predicting landslides. Here, based on high frequency acquisitions of the PlanetScope satellite constellation, we study the kinematics of a large landslide located in Peru that failed in June 2020. We show that the landslide underwent a progressive acceleration in the 3 months before its failure, reaching at most 8 m of total displacement. The high frequency of satellite revisit allows us to apply the popular Fukuzono method for landslide time-of-failure prediction, with sufficient confidence for faster moving areas of the landslide. These results open new opportunities for landslide precursors detection from space, but also show the probable seldom applicability of the optical satellites for landslide time-of-failure prediction. Many catastrophic landslides are preceded by specific movements, for example, a constant increase in velocity over time. These accelerations form the basis for predicting the landslide time-of-failure. The measurement of these movements is usually based on instruments installed on the landslide itself. However, this instrumentation is not always possible and, in recent years, the acquisition of satellite images at increasingly higher frequencies (e.g., PlanetScope satellites with a revisit frequency of less than 1 day) has raised interest in landslide monitoring and prediction. In order to assess the capability of PlanetScope satellites for this prediction, we analyze here the pre-failure movements of a large landslide in southern Peru, which collapsed in June 2020 and dammed a river. We show that the landslide underwent a progressive acceleration in the 3 months prior to its failure, reaching a total displacement of 8 m. Based on the displacement time-series of the fastest areas of the landslide, we predict the landslide time-of-failure 3 weeks in advance. Despite these encouraging results for landslide precursor detection from space, this study also shows the seldom use of optical satellites for landslide time-of-failure prediction. High frequency optical satellites can detect the acceleration precursory to the Achoma landslide failureThe acceleration follows a Voight law, classical of the tertiary creep of materialsThe time-series of ground displacement may be used to predict the time-of-failure for pixels of total displacement larger than 5 m
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Lauer, A. R., Hellmann, R., Montes-Hernandez, G., Findling, N., Ling, W. L., Epicier, T., et al. (2023). Deciphering strontium sulfate precipitation via Ostwald's rule of stages: From prenucleation clusters to solution-mediated phase tranformation. Journal Of Chemical Physics, 158(5).
Résumé: Multiple-step nucleation pathways have been observed during mineral formation in both inorganic and biomineral systems. These pathways can involve precursor aqueous species, amorphous intermediates, or metastable phases. Despite the widespread occurrence of these processes, elucidating the precise nucleation steps and the transformation mechanisms between each step remains a challenging task. Using a suite of potentiometric, microscopic, and spectroscopic tools, we studied the nucleation pathway of SrSO4 as a function of the physico-chemical solution parameters. Our observations reveal that below a threshold supersaturation, nucleation is driven by bound species, akin to the prenucleation cluster model, which directly leads to the formation of the stable phase celestine, SrSO4. At higher supersaturations, this situation is altered, with nucleation dominated by the consumption of free ions. Importantly, this change in nucleation mechanism is coupled to the formation of a hemihydrate metastable phase, SrSO4 & BULL; 1/2H(2)O, which eventually transforms into celestine, adhering to Ostwald's rule of stages. This transformation is a solution-mediated process, also occurring in the presence of a fluid film and is controlled by the physico-chemical parameters of the surrounding environment. It proceeds through the dissolution of the metastable phase and the de novo crystallization of the final phase. Overall, our results reveal that ion association taking place during the prenucleation stage dictates whether the nucleation pathway goes through an intermediate phase or not. This also underlines that although Ostwald's rule of stages is a common process, it is not a prerequisite for mineral formation-even in systems where it can occur.
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Lave, J., Guerin, C., Valla, P. G., Guillou, V., Rigaudier, T., Benedetti, L., et al. (2023). Medieval demise of a Himalayan giant summit induced by mega-landslide. Nature, 619(7968), 94–+.
Résumé: Despite numerous studies on Himalayan erosion, it is not known how the very high Himalayan peaks erode. Although valley floors are efficiently eroded by glaciers, the intensity of periglacial processes, which erode the headwalls extending from glacial cirques to crest lines, seems to decrease sharply with altitude(1,2). This contrast suggests that erosion is muted and much lower than regional rock uplift rates for the highest Himalayan peaks, raising questions about their long-term evolution(3,4). Here we report geological evidence for a giant rockslide that occurred around 1190 ad in the Annapurna massif (central Nepal), involving a total rock volume of about 23 km(3). This event collapsed a palaeo-summit, probably culminating above 8,000 m in altitude. Our data suggest that a mode of high-altitude erosion could be mega-rockslides, leading to the sudden reduction of ridge-crest elevation by several hundred metres and ultimately preventing the disproportionate growth of the Himalayan peaks. This erosion mode, associated with steep slopes and high relief, arises from a greater mechanical strength of the peak substratum, probably because of the presence of permafrost at high altitude. Giant rockslides also have implications for landscape evolution and natural hazards: the massive supply of finely crushed sediments can fill valleys more than 150 km farther downstream and overwhelm the sediment load in Himalayan rivers for a century or more.
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Le Boulzec, H., Mathy, S., Verzier, F., Andrieu, B., Monfort-Climent, D., & Vidal, O. (2023). Material requirements and impacts of the building sector in the Shared Socioeconomic Pathways. Journal Of Cleaner Production, 428.
Résumé: The significant weight of the building sector in global material demand has been addressed in several publications, but a lack of consideration of the energy-materials nexus was identified. To fill this gap, we developed a stock-flow dynamic model from 1950 to 2100, using scenarios of the International Energy Agency and the Shared Socioeconomic Pathways of the academic literature. We find that (i) the increasing stocks in the less developed countries results in a rise of the inflows; (ii) strong inequalities are observed in the in-use stocks per capita of materials in the SSPs, despite optimistic material intensities projection, (iii) a growing materials demand translates into larger final energy demand of material production, which could question the feasibility of some low-energy demand scenarios, and that (iv) the recycled concrete aggregated display a significant potential to enhance the reduction of accumulated concrete stocks in landfills and green concrete could decrease the energy demand of concrete production. We furthermore highlight the crucial temporal aspect of policies to successfully implement these solutions, as long lifetimes are observed in the building sector.
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Le Breton, M., Baillet, L., & Larose, E. (2023). Tomography of the quantity of grass using RFID propagation-based sensing.
Résumé: Passive RFID tags have diverse low-cost sensing applications, with sensors either connected to the tag or the tag antenna acting as a sensor, allowing close-range measurements. However, an emerging approach utilizes wave propagation for remote sensing without physical contact. This study investigates how wave propagation across dense grass alters the phase difference of arrival, enabling the estimation of vegetation volume ratio. A tag positioned 19 meters from the reader is moved vertically into a dense grass medium, then without grass. By analyzing the change in phase measurements caused by the wave slowness in the medium, the grass volume ratio can be estimated. The RFID-based estimate of 0.75% aligns with the 0.53% obtained from weight measurements. Looking forward, this method might help to monitor crops in agriculture, but also to sense other complex medium.
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Le Breton, M., Larose, E., Baillet, L., Lejeune, Y., & van Herwijnen, A. (2023). Monitoring snow water equivalent using the phase of RFID signals. Cryosphere, 17(8), 3137–3156.
Résumé: The amount of water contained in a snowpack, known as snow water equivalent (SWE), is used to anticipate the amount of snowmelt that could supply hydroelectric power plants, fill water reservoirs, or sometimes cause flooding. This work introduces a wireless, non-destructive method for monitoring the SWE of a dry snowpack. The system is based on an array of low-cost passive radiofrequency identification (RFID) tags, placed under the snow and read at 865- 868 MHz by a reader located above the snow. The SWE was deduced from the phase delay of the tag's backscattered response, which increases with the amount of snow traversed by the radiofrequency wave. Measurements taken in the lab-oratory, during snowfall events and over 4.5 months at the Col de Porte test field, were consistent with reference mea-surements of cosmic rays, precipitation and snow pits. SWE accuracy was +/- 18 kg m(-2) throughout the season (averaged over three tags) and +/- 3 kg m(-2) during dry snowfall events (averaged over data from two antennas and four or five tags). The overall uncertainty compared to snow weighing was +/- 10 % for snow density in the range 61-390 kg m(-3). The main limitations observed were measurement bias caused by wet snow (biased data were discarded) and the need for phase unwrapping. The method has a number of advantages: it al-lows for continuous measurement (1 min sampling rate in dry snow), it can provide complementary measurement of tag temperature, it does not require the reception of external data, and it opens the way towards spatialized measurements. The results presented also demonstrate that RFID propagation-based sensing can remotely monitor the permittivity of a low-loss dielectric material with scientific-level accuracy.
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Lecointre, A., Roux, P., Bouttier, P. - A., Picard, C., & Louvet, V. (2023). A graph approach for fast dense array inter-station phase delay interpretation. Geophysical Journal International, 235(2), 1260–1273.
Résumé: We present a phase-delay detection procedure adapted for seismic arrays composed of a large number of stations. We use graph formalism to introduce a direct method to compute station phase delays starting from inter-station phase differences deduced from noise cross-correlation functions. We focus this study on surface wave main arrival as phase-difference evaluation at each station requires high coherence level. Then, we perform numerical experiments with synthetic data computed as a realistic and dense network of 79 stations in a 400 by 400 km(2 )square box. For one of the 79 stations, we simulate a phase difference of 15 per cent of the signal period. Further, we evaluate the accuracy and precision of phase-delay estimation at each station with regard to the quality of the cross-correlation functions (i.e. the signal-to-noise ratio). When the inter-station coherence levels are larger than 0.6 (i.e. a high-quality signal), we show good agreement between the phase-delay estimation and its expected value of 15 per cent of the signal period. We introduce a coherence-weighted estimate of phase delay and show that applying this weighting allows us to be less vulnerable to phase-delay underestimation for intermediate-quality signals. Then, the method is applied to experimental data recorded by a high density nodal array with 923 vertical geophones with 19 d of continuous records, centred on the 600 by 600 m(2) damage zone of the Clark branch of the San Jacinto Fault Zone, Southern California (USA). We verify that the San Jacinto network is well synchronized, as most of the estimated phase delays are less than 2 per cent of the central period of the signal, and they are associated with high levels of inter-station coherence. More surprisingly, the spatial features of the estimated phase delays show deterministic geographical patterns that are related to topography and that exhibit similarities with phase velocity maps at 4 . 5 Hz from previous 3-D v elocity inv ersions. This suggests that the topo graphic ef fect may be accounted for to estimate accurate phase dela ys. Also, w e note that the temporal variability of the estimated phase delays in the case of the San Jacinto data set are related to atmospheric forcing. Our direct method for estimating phase delays is applicable to structure-oriented monitoring studies, and it opens perspectives in the monitoring of seismic velocity variations.
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Lee, Y. - H., Cook, K. L., Tan, X. - B., Chu, M. - F., Chiu, H. - Y., Li, Q. - L., et al. (2023). U-Pb ages of Gongga Shan granite, western Sichuan and its implication to the tectonic evolutions of eastern Tibet. Frontiers In Earth Science, 11.
Résumé: The eastern margin of the Tibetan Plateau has given rise to much debate about mechanisms of plateau uplift and evolution and, in particular, the role of the lower crust in crustal thickening. Knowledge of the middle to lower crust conditions is critical for evaluating various models of crustal deformation, but data on crustal evolution through time are lacking. Here, we turn to the Gongga Shan granite, an intrusion along the Xianshuihe fault in easternmost Tibet that directly records local Cenozoic crustal conditions. We present 124 U-Pb samples from the Gongga Shan granite (GSG) that prove that the crust has been stepwise producing partial melt from 56 Ma to 4 Ma. According to the age distribution, the GSG can be separated into four major groups with ages of 4-10 Ma, 12-20 Ma, 25-40 Ma, and 43-56 Ma. Combining the timing information with geophysics and low-temperature thermochronology data, we suggest that events younger than 10 Ma may indicate the onset of recent crustal channel flow in the middle to lower crust. In contrast, the youngest 4 Ma ages indicate the ongoing partial melting of the middle crust. The 12-20 Ma events could be related to an earlier stage of crustal channel flow, consistent with the regional large-scale crustal channel flow in central Tibet.
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Lemot, F., Valla, P. G., Beek, P. van der, Jagercikova, M., Niedermann, S., Carcaillet, J., et al. (2023). Miocene cave sediments record topographic, erosional and drainage development in the Western European Alps. Earth And Planetary Science Letters, 621.
Résumé: The dynamic Neogene evolution of the Western European Alps included exhumation of the external crystalline massifs, thrust propagation to the foreland, drainage network reorganization, and major climatic variations. To constrain possible interactions between those factors, accurate geomorphological and sedimentological archives are required. However, intra-orogenic areas are subject to erosion, and extensive glacial cover during the Quaternary erased most of the geomorphic markers in the Alps. For these reasons, the genesis of the main features of the modern landscape, such as the major valleys and the drainage network, remains poorly understood. This study highlights how recently discovered karstic archives from the perched paleo-karst of the Obiou peak (Devoluy massif, SE France) record the tectonic and drainage-network evolution of this part of the Alps during the Neogene. The Obiou caves are located at 2250-2380 m elevation, similar to 1600 m above the modern Drac valley; they contain fluvial deposits including sand-clay units and rounded crystalline cobbles derived from the adjacent Ecrins-Pelvoux massif. As the Devoluy and Ecrins-Pelvoux massifs are currently separated by the axial Drac valley (a major tributary of the Isere River), these cave sediments must have been deposited by a radial drainage system before incision of the modern Drac. We report new multi-method results from these sediments, including cosmogenic-nuclide burial dating (21Ne, 10Be, 26Al in quartz), provenance analysis (clast petrography and heavy-mineral analysis), and detrital thermochronology (apatite fission-track and (U-Th)/He) combined with a paleo-environmental reconstruction from palynology. 21Ne/10Be dating of cobbles and sand constrains the burial age to 11.5 +/- 1.5 Ma, providing a maximum age for the modern axial drainage system and a minimum long-term incision rate of similar to 140 m/Myr for the Drac valley. Comparison of the combined data to both modern rivers and nearby Oligocene foreland-basin deposits provides evidence for two successive drainage reorganizations. Early Miocene exhumation and development of high topography in the Ecrins-Pelvoux massif, linked to localized thrusting on a crustal-scale ramp, led to initial deflection of the antecedent radial drainage network, beheading its headwaters by establishment of the axial upper Durance valley. Subsequent propagation of thrusting into the subalpine Devoluy massif and associated uplift during the mid to late Miocene led to establishment of the modern drainage system. (c) 2023 Elsevier B.V. All rights reserved.
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Leon-Loya, R., Lacan, P., Ortuno, M., Zuniga, F. R., Stepancikova, P., Stemberk, J., et al. (2023). Paleoseismology of a Major Crustal Seismogenic Source Near Mexico City: The Southern Border of the Acambay Graben. Tectonics, 42(6).
Résumé: The Trans-Mexican Volcanic Belt is an active continental volcanic arc related to subduction along the Middle America trench. It is characterized by intra-arc extension resulting into several major arc-parallel active fault systems and tectonic basins. The Acambay graben, one of the largest of these basins, is located near Mexico City, in the central part of this province. In 1912, a M 6.9 earthquake ruptured the surface along the northern border of the graben together with at least two other faults. In this paper, we analyze the paleoseismic history of the southern border of the Acambay Graben, with new observations made in one natural outcrop and four paleoseismological trenches excavated across branches of the Venta de Bravo Fault at the site where it overlaps with the Pastores Fault. We present evidence of at least two paleo-earthquakes that occurred between 12,190 +/- 175 and 5,822 +/- 87 cal year BP and between 647 +/- 77 and 250 cal year BP. On one of these branches, we estimate a minimum slip-rate value between 0.1 and 0.23 mm/year for the last 12 ka and a mean recurrence interval of 8.5 +/- 3 ka. By considering several likely rupture lengths along the Venta de Bravo and Pastores faults, we calculated a maximum possible magnitude of M-w 7.01 +/- 0.27. Finally, by correlating events recorded along different faults within the Acambay Graben, we discuss several possible rupture coalescent scenarios and related consequences for Mexico City.
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Leonardo-Suarez, M., Hernandez, A. F., & Quinde, P. (2023). A far-field ground motion prediction model for interface earthquakes at the hill zone of Mexico City. Journal Of Seismology, 27(1), 115–141.
Résumé: This study presents an updated attenuation model to predict the peak ground acceleration (PGA), peak ground velocity (PGV), 5% damped pseudo-spectral acceleration (SA), and the average spectral acceleration (AvgSA) at the hill zone of Mexico City for interface earthquakes. The strong-motion dataset comprises 33 earthquakes recorded at CU station, covering a moment magnitude (M-w) range from 6.0 to 8.1 and a source-to-site distance (R-rup) range from 240 to 490 km. Given the small number of available observations, a Bayesian regression scheme is used to obtain the coefficients of the ground-motion prediction model (GMPM). In addition, the epistemic uncertainty in the estimation of the regression coefficients is evaluated, showing its impact on the framework of a probabilistic seismic hazard analysis (PSHA). The results are compared with models previously developed for the CU station, discussing the differences observed between the median predictions and their standard deviations. Likewise, seismic hazard curves are computed and compared with empirical curves obtained by counting the number of times per year that a given value of ground-motion intensity is exceeded. The results show that the dispersion of the GMPM proposed is lower than the previous models for PGA and SA, which means better predictability and more reliable estimates of the seismic hazard at the site.
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Lerbet, J., Challamel, N., Nicot, F., & Darve, F. (2023). Intrinsic incremental evolution of hypoelastic discrete mechanical systems. Zamm-Zeitschrift Fur Angewandte Mathematik Und Mechanik, .
Résumé: This paper provides an explicit geometric and coordinate-free formulation of incremental discrete mechanics in the framework of potentially non integrable hypoelasticity. First, the general framework is developed in order to tackle hypoelasticity as an Ehresmann connection on the cotangent bundle T*M. Two types of incremental evolutions may be distinguished, the weak or integrable incremental evolutions and the strong or non integrable incremental evolutions, according to the nature of the hypoelastic constitutive law. The geometric structure of the double tangent bundle TT*M is fully used in order to get the geometric counterpart kappa of the so-called tangent stiffness matrix. Subject to specific conditions in TT*M, the incremental evolution is then a well-founded question. An hypoelastic four-grains granular system illustrates in detail these general results.
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Lherm, V., & Deguen, R. (2023). Velocity field and cavity dynamics in drop impact experiments. Journal Of Fluid Mechanics, 962.
Résumé: Drop impact experiments allow the modelling of a wide variety of natural processes, from raindrop impacts to planetary impact craters. In particular, interpreting the consequences of planetary impacts requires an accurate description of the flow associated with the cratering process. In our experiments, we release a liquid drop above a deep liquid pool to investigate simultaneously the dynamics of the cavity and the velocity field produced around the air-liquid interface. Using particle image velocimetry, we analyse quantitatively the velocity field using a shifted Legendre polynomial decomposition. We show that the velocity field is more complex than considered in previous models, in relation to the non-hemispherical shape of the crater. In particular, the velocity field is dominated by degrees 0 and 1, with contributions from degree 2, and is independent of the Froude and the Weber numbers when these numbers are large enough. We then derive a semi-analytical model based on the Legendre polynomial expansion of an unsteady Bernoulli equation coupled with a kinematic boundary condition at the crater boundary. This model explains the experimental observations and can predict the time evolution of both the velocity field and the shape of the crater, including the initiation of the central jet.
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Li, C., Li, T., Hollingsworth, J., Zhang, Y., Qian, L., & Shan, X. (2023). Strain Threshold for the Formation of Coseismic Surface Rupture. Geophysical Research Letters, 50(16).
Résumé: The 2021 M-w 7.4 Maduo earthquake (eastern Tibetan Plateau), with a surface deformation zone that is characterized by multiple distinct surface rupture segments separated by segments with no surface ruptures, provides an excellent opportunity to constrain the strain threshold (minimum strain) for the formation of surface ruptures. Through sub-pixel correlation of pre- and post-event SPOT-6/7 satellite images (pixel = 1.5 m), we derive surface displacement and shear-strain fields of the Maduo earthquake. By quantifying the minimum shear strain along the surface rupture segments and the maximum shear strain along the segments with no surface ruptures, we estimate a rupture strain threshold, which ranges from 0.8% to 1.8% and appears to decrease with structural maturity of the causative fault. This threshold is generally consistent with a rupture strain limit (0.5%-1.5%) of intact rocks from laboratory measurements, and is higher than a commonly-assumed strain threshold (0.5%) for inelastic deformation.
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Llovet, X., Gavrilenko, M., Batanova, V. G., & Sobolev, A., V. (2023). Element Depletion Due to Missing Boundary Fluorescence in Electron Probe Microanalysis: The Case of Ni in Olivine. Microscopy And Microanalysis, 29(5), 1595–1609.
Résumé: Secondary fluorescence (SF) is known to be a potential source of error in electron probe microanalysis (EPMA) when analyzing for a trace or minor element near a phase boundary. This often overlooked effect leads to a concentration enhancement whenever the neighboring phase contains a high concentration of the analyzed element. Here we show that SF may also lead to a concentration decrease, which can be mistakenly interpreted as a depletion. To examine this issue, we compare Ni profiles measured on well-characterized, homogeneous olivine [(Mg,Fe)2SiO4] grains embedded in basaltic glass, with semi-analytical calculations and numerical simulations of SF across phase boundaries. We find that the Ni content consistently decreases with decreasing distance to the interface or grain radius, deviating from the expected concentration by & SIM;2-5% at 10 & mu;m from the interface. This decrease is explained by the lower bremsstrahlung fluorescence emitted from the sample as compared to that emitted from the standard. The analytical error due to boundary fluorescence affecting other elements of petrologic importance in olivine is discussed.
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Lopez, A. C., Pimentel, C., & Pina, C. M. (2023). Mineral evolution and mineral niches of ammonium sulfates: The case of Pastora mine, Aliseda, Spain. American Mineralogist, 108(7), 1376–1383.
Résumé: The uncommon association of ammonium sulfates identified in the Pastora abandoned mine is the result of a complex mineral evolution. By means of dissolution-(re)crystallization reactions operating during long periods of time, ammonium minerals “adapt” to local spatiotemporal changes in physico-chemical conditions. We found that during such an evolution, seasonal variations in temperature and humidity, the relative solubility of mineral species, and the presence of organic matter play an important role. In addition, our study shows the existence of “mineral niches” and “mineral seasonality,” which can be explained on the basis of the “mineral ecology” concept introduced by Hazen et al. (2015). Our investigation of the formation of hydrated sulfates, particularly of ammonium sulfates, might be of importance for identifying the existence of life in mineral formation environments.
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Machacca, R., Lesage, P., Tavera, H., Pesicek, J. D., Caudron, C., Torres, J. L., et al. (2023). The 2013-2020 seismic activity at Sabancaya Volcano (Peru): Long lasting unrest and eruption. Journal Of Volcanology And Geothermal Research, 435.
Résumé: Sabancaya volcano is the youngest and second most active volcano in Peru. It is part of the Ampato-Sabancaya volcanic complex which sits to the south of the ancient Hualca Hualca volcano and several frequently active faults, thus resulting in complex volcano-tectonic interactions. After 15 years of repose, in 2013, a series of 4 earthquakes with magnitude >4.5 occurred within 24 h, marking the beginning of a new episode of unrest. Several additional swarms of earthquakes occurred in the following years until magmatic eruptive activity started on 6 November 2016. This activity is ongoing as of this writing, with an average of 50 explosions per day. In this study, we present results of multiparametric monitoring of Sabancaya's activity observed during 2013-2020. Seismic data are used to create a one-dimensional seismic velocity model, to catalog, locate, and characterize earthquakes, to detect repeating earthquake families, and to monitor seismic velocity variations by ambient noise cross-correlation. These analyses are complemented by visual and remote sensing observations and ground deformation measurements. All monitored parameters showed significant changes on 6 November 2016, the day of eruption onset, thus dividing the eruptive activity into pre-eruptive and eruptive stages.The unrest is characterized by high levels of seismic activity with hundreds of events detected per day. Volcano-tectonic (VT) earthquakes were dominant during the pre-eruptive period while long-period (LP) events and explosions have been most numerous since the eruption onset. Earthquake locations highlight long-lasting seismogenic zones along multiple previously active regional faults, as well as along newly identified faults. This VT seismicity is mainly distributed in a sector from the northwest to the east of the volcanic complex at distances of up to 30 km from the crater. We focus our analysis on two eruptive episodes: the eruption onset and subsequent crater migration from south to north, and the increase of lava dome extrusion rate in 2019. Both episodes are accompanied by seismic velocity decreases of up to 0.2% and are preceded by a few weeks by bursts of distal VT activity, including numerous repeating earthquakes. These repeated events were located on several remote tectonic faults (5-25 km from the vent). We suggest that these phenomena could be due to the injection of a batch of magma in the deep reservoir and/or conduit, which would generate 1) a pressure wave propagating in the hydrothermal system, triggering the bursts of seismic activity and 2) slow rising of magma by melting old material filling the conduit that eventually produced the eruptive and dome growth acceleration events.
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Madathiparambil, A. S., Tekseth, K. R., Murer, F. K., Cordonnier, B., Agofack, N., McBeck, J., et al. (2023). Time-Resolved<i> In</i><i> Situ</i> Imaging of Strain Localization in Draupne Shale under Triaxial Compression. Physical Review Applied, 20(3).
Résumé: Understanding the mechanical behavior of rocks is crucial in subsurface activities, including storage of carbon dioxide and hydrogen gases, which both rely on shale caprocks as potential sealing barriers. Several current large-scale initiatives focus on potential carbon storage in North Sea aquifers. The Draupne Formation contains a series of shale layers interbedded with sandstone layers, the overall thickness of which varies in the range from tens to hundreds of meters. Injection of carbon dioxide into the underlying sandstone reservoirs leads to changes in the surrounding stress field, which can result in fault reactivation or the creation of microfractures, and thus, alter the performance of the shale caprock. Time-resolved microcomputed tomography (4D μCT) has, in recent years, become a powerful technique for studying the mechanical properties of rocks under stress conditions similar to those prevailing in geological reservoirs. Here, we present results from experiments performed on Draupne shale using a triaxial rig combined with 4D μCT based on synchrotron radiation. Detailed mechanical analysis of the tomography datasets by digital volume correlation reveals the three-dimensional pattern of the temporally evolving deformation field. Intermittent bursts of deformation at different locations within the specimen are observed, which eventu-ally evolve into a major fracture plane extending laterally across the whole sample. This study suggests that the pseudolinear-elastic-appearing behavior in the macroscopic stress-strain relationship previously reported for Draupne shale samples could consist of a series of irreversible processes occurring at various weak points within the sample. The combination of 4D μCT imaging with strain analysis enables in situ investigations of deformation processes via quantification of shear and volumetric strains within the sample, thus providing an improved understanding of the fracture dynamics of shales.
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Madeja, B., Gebauer, D., Marsiske, M. R., Ott, A., Rueckel, M., Rosenberg, R., et al. (2023). New insights into the nucleation of portlandite and the effects of polymeric additives. Cement And Concrete Research, 173.
Résumé: The crystallization of calcium hydroxide (Ca(OH)2, CH, portlandite) is a key process during the early stages of cement hydration. In the present work, we have revisited the formation of this mineral through nucleation and growth from supersaturated aqueous solutions, in the light of the currently emerging picture of multistage “nonclassical” crystallization. To that end, we developed a titration-based assay, in which stock solutions of both relevant ions are added simultaneously into a reservoir, where supersaturation increases slowly at constant stoichiometry until nucleation occurs. This procedure allows both pre- and early post-nucleation phenomena to be analyzed quantitatively. Complementarily, the early stages of portlandite mineralization were probed by various advanced characterization techniques, including cryo-transmission electron microscopy (cryo-TEM), insitu small-angle X-ray scattering (SAXS), pair distribution function (PDF) analysis of high-energy X-ray scattering (HEXS) data, and analytical ultracentrifugation (AUC). The experimental data show that the formation of calcium hydroxide starts with the association of ions into complexes and clusters, which subsequently coalesce to form amorphous nanoparticles – much like what has been observed in the case of calcium carbonate and other prominent minerals. Subsequently, these particles aggregate and build networks, which eventually transform into hexagonal Ca(OH)2 crystals. The presence of a soluble polycarboxylate – as a known inhibitor of portlandite crystallization – does not change the main characteristics of this multistep nucleation pathway, but it proved capable of significantly extending the lifetime of the amorphous intermediate phase and thus delaying the transition to the final crystalline phase. Our observations confirm the notion that “non-classical” crystallization is a much more common phenomenon than initially believed – and that, for minerals forming in aqueous environments, it may actually be the rule rather than the exception.
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Majstorovic, J., Giffard-Roisin, S., & Poli, P. (2023). Interpreting convolutional neural network decision for earthquake detection with feature map visualization, backward optimization and layer-wise relevance propagation methods. Geophysical Journal International, 232(2), 923–939.
Résumé: In the recent years, the seismological community has adopted deep learning (DL) models for many diverse tasks such as discrimination and classification of seismic events, identification of P- and S-phase wave arrivals or earthquake early warning systems. Numerous models recently developed are showing high accuracy values, and it has been attested for several tasks that DL models perform better than the classical seismological state-of-art models. However, their performances strongly depend on the DL architecture, the training hyperparameters, and the training data sets. Moreover, due to their complex nature, we are unable to understand how the model is learning and therefore how it is making a prediction. Thus, DL models are usually referred to as a 'black-box'. In this study, we propose to apply three complementary techniques to address the interpretability of a convolutional neural network (CNN) model for the earthquake detection. The implemented techniques are: feature map visualization, backward optimization and layer-wise relevance propagation. Since our model reaches a good accuracy performance (97%), we can suppose that the CNN detector model extracts relevant characteristics from the data, however a question remains: can we identify these characteristics? The proposed techniques help to answer the following questions: How is an earthquake processed by a CNN model? What is the optimal earthquake signal according to a CNN? Which parts of the earthquake signal are more relevant for the model to correctly classify an earthquake sample? The answer to these questions help understand why the model works and where it might fail, and whether the model is designed well for the predefined task. The CNN used in this study had been trained for single-station detection, where an input sample is a 25 s three-component waveform. The model outputs a binary target: earthquake (positive) or noise (negative) class. The training database contains a balanced number of samples from both classes. Our results shows that the CNN model correctly learned to recognize where is the earthquake within the sample window, even though the position of the earthquake in the window is not explicitly given during the training. Moreover, we give insights on how a neural network builds its decision process: while some aspects can be linked to clear physical characteristics, such as the frequency content and the P and S waves, we also see how different a DL detection is compared to a visual expertise or an STA/LTA detection. On top of improving our model designs, we also think that understanding how such models work, how they perceive an earthquake, can be useful for the comprehension of events that are not fully understood yet such as tremors or low frequency earthquakes.
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Makinen, T., Weiss, J., Amitrano, D., & Roux, P. (2023). History effects in the creep of a disordered brittle material. Physical Review Materials, 7(3).
Résumé: We study the creep behavior of a disordered brittle material (concrete) under successive loading steps, using acoustic emission and ultrasonic sensing to track internal damage. The primary creep rate is observed to follow a (Omori-type) power-law decay in the strain rate, the number of acoustic emission events, as well as the amplitudes of the ultrasonic beams, supporting a brittle-creep mechanism. The distribution of acoustic emission event energies is observed to have a scale-free power-law distribution instead of a truncated one expected for a system approaching a critical point at failure. The main outcome is, however, the discovery of unexpected history effects that make the material less prone to creep when it has been previously deformed and damaged under primary creep. With the help of a progressive damage model implementing thermal activation, we interpret this as an aging-under-stress phenomenon: During an initial creep step at relatively low applied stress, the easy-to-damage sites are exhausted first, depleting the excitation spectrum at low stress gap values. Consequently on reloading, although previously damaged, the primary creep restarts but the material creeps (and damages) less than it would under the same stress but without precreeping. Besides shedding a new light on the fundamental physics of creep of disordered brittle materials, this has important practical consequences in the interpretation of some experimental procedures, such as stress-stepping experiments.
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Malvoisin, B., & Brunet, F. (2023). Barren ground depressions, natural H2 and orogenic gold deposits: Spatial link and geochemical model. Science Of The Total Environment, 856.
Résumé: A review of the localities in continental rocks where H2-rich gases have been reported, showed that they are mainly located near orogenic gold deposits. Two types of geomorphological features known as markers of gas venting in sed-imentary basins were also systematically observed near orogenic gold deposits on satellite images. They consist in both barren ground depressions and high densities of small (<20 m in diameter) circular-and comet-shaped white spots in 32 and 7 localities, respectively. Point pattern analysis revealed that the white spots are self-organized, and similar to previously described vegetation patterns associated with termite mounds and fairy circles. We proposed a geochemical model to account for this relationship between orogenic gold deposits, H2 emanations and geomorphological features. Fe-carbonates are ubiquitous mineral products associated with gold mineralization. They can further dissolve in the presence of aqueous fluid due to their high reactivity below 200 degrees C to produce magnetite and up to-1 mol H2 per kg of rock along with-3 mol/kg CO2. This process induces a solid volume decrease of 50 %. Therefore, we propose that Fe-carbonate dissolution is (1) the primary source of H2 in orogenic gold deposit areas, and (2) involved in the formation of the geomorphological structures reported here, providing a new framework to understand their seem-ingly complex formation. Ground depressions and white spots are possible tools for gold exploration. Actually, we identified four new areas where we suspect possible orogenic gold deposits. The association between H2-rich gas and ground depressions was also made near other formations containing Fe-carbonates such as iron formations and carbonatites. This suggests that H2 production through Fe-carbonate dissolution is not restricted to gold deposits. The global H2 production in crustal rocks associated with Fe-carbonate alteration is estimated to 3 x 105 mol/yr.
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Manceau, A., Mathon, O., Lomachenko, K. A., Rovezzi, M., Kvashnina, K. O., Boiron, M. - C., et al. (2023). Revealing the Incorporation of Cerium in Fluorapatite. Acs Earth And Space Chemistry, 8(1), 119–128.
Résumé: Fluorapatite (FAp, nominally Ca-5(PO4)(3)F) is the most common phosphate mineral at the Earth's surface and a main host for rare-earth elements (REE) in magmatic and hydrothermal ore deposits and in marine sediments. Our understanding of the enrichment process of REE in FAp rests upon two foundations: (1) being able to elucidate the thermodynamic driving force for their partitioning between Ca1 and Ca2 structural sites and (2) being able to determine how the substitution of REE(III) for Ca(II) is charge-compensated. A main unsolved question is the marked preference of the larger light REE (lanthanum -> samarium) for the smaller Ca2 site. We used density functional theory (DFT) and high-energy-resolution fluorescence-detected extended X-ray absorption fine structure (HERFD-EXAFS) spectroscopy to gain detailed insight into the bonding energy, electronic structure, and short-range order of cerium (Ce) in natural magmatic/hydrothermal FAp. Results show that Ce(III) has a marked preference for a Ca2 site where the nearest five-valent phosphorus cation is replaced with a tetravalent silicon cation, thus balancing the charge excess of the Ce impurity locally. Atomic charge calculations show that the Ca2 site is more ionic than the Ca1 site and that the energetics of the site preference are linearly correlated to the ionization energy of the substituent. Cations with a low energy of ionization, such as Ce, preferably occupy the Ca2 site. Novel combination of HERFD-EXAFS spectroscopy and DFT appears to be the most straightforward and reliable way to assess the crystal chemistry of trace elements in compositionally complex natural materials and opens a previously unavailable avenue for mechanistic investigation of metal enrichment in ore deposits.
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Mari, J. L., Delay, F., Voisin, C., & Gaudiani, P. (2023). Active and Passive acoustic logging applied to the detection of preferential flow in a sedimentary aquifer. Science And Technology For Energy Transition, 78.
Résumé: Two boreholes of an experimental site located in the Cher region (France) were investigated via Full Waveform Acoustic Logging (FWAL). The acoustic tool used for the FWAL experiments is a flexible monopole tool holding two pairs of piezoelectric receivers and a magnetostrictive transducer. The tool was modified to perform both active and passive FWAL. To our knowledge, this change is a novelty. For passive acoustic logging, several runs were recorded to obtain a set of acoustic noise sections from which noise Root Mean Squared (RMS) amplitude logs and spectral amplitude logs in different frequency bandwidths were computed. The acoustic logs resulting from passive acoustic monitoring were compared with P-wave acoustic velocity, core data, and a flowmeter log. It is shown that: (1) the distribution of noise frequencies in the 0-5 kHz is strongly correlated with the variations of the flowmeter, (2) the distribution of noise frequencies and noise RMS amplitude is correlated with the lithology (core description), and the P-wave velocity log. As the noise is simultaneously recorded by two receivers of the tool, an interference noise section was elaborated by correlating and summing pairs of acoustic traces at each depth. This procedure, which can be interpreted as an interferometry analysis, points out the presence of low-frequency waves identified as Stoneley waves. It is shown that the Stoneley wave velocity obtained in passive mode can be used to estimate the shear velocity of the formation.
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Marin-Troya, P., Espinosa, C., Monasterio-Guillot, L., & Alvarez-Lloret, P. (2023). Carbonate Minerals' Precipitation in the Presence of Background Electrolytes: Sr, Cs, and Li with Different Transporting Anions. Crystals, 13(5).
Résumé: Carbonate minerals are largely associated with many geological and biological environments as well as several industrial and technological processes. The crystalline characteristics of these mineral phases can be modified by background salts present in the solution due to the effect of different electrolytes on the dynamics of ion-water interactions and ionic strength during precipitation. In the current research, we studied the effect of the presence of several electrolytes (i.e., Cs, Li, and Sr), combined with chloride and carbonate as transporting anions, on the growth and mineral evolution processes of carbonate precipitation in solution. The electrolyte composition during the reaction (experimental times from 24 h up to 30 days) determined the formation of specific calcium carbonate polymorphs. The Li presence induced the formation of vaterite which was progressively transformed into calcite during the reaction time, while Cs stabilized the calcite formation. The Sr presence in the system caused the precipitation of strontianite with modifications in its cell parameters and the structural arrangement of the carbonate molecular group. During the mineral evolution considering chloride and carbonate experimental set-ups, several compositional and cell parameters/crystallinity variations of the carbonated phases were also observed. A better understanding of the relationship between the compositional properties of the aqueous solvent and the crystallization mechanisms can contribute to a deeper comprehension of the mineral precipitation and transformation in different multicomponent solutions that occur in natural environments and in controlled synthesis processes.
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Marsan, D., Reverso, T., & Socquet, A. (2023). Earthquake swarms along the Chilean subduction zone, 2003-2020. Geophysical Journal International, 235(3), 2758–2777.
Résumé: We search for earthquake swarms along the Chilean subduction, from -18 degrees to -39 degrees of latitude, 2003-2020 by developing an objective, model-based method that detects potential swarms as anomalous changes in earthquake rate. A set of 16 swarms is obtained after careful inspection of the candidate swarms; this assessment allows to reject cases for which model errors, rather than 'true' anomalous rate changes, are likely the cause of the detection. Averaging the activity over these 16 episodes, we find indirect evidence for a mostly aseismic driving mechanism, and a mean aseismic to seismic ratio estimated to range between 40 and 90 when using the seismicity rate as a proxy for slip. All the swarms are found in the 20-50 km depth range with the notable exception of one 60-100-km-deep swarm that occurs several days after the 2010 Maule earthquake and downdip of it. The dominant depth range (20-50 km) is in agreement with previous studies that suggest this range to be a transition zone from the shallower, locked part of the subduction, to the freely slipping interface at greater depth and intraslab earthquake activity. The swarms can be separated into three spatial groups, two of which being related to a subducting oceanic ridge. This structural control by fluid-rich geological features is modulated by stress control, that is swarms cluster in time with intermediate to large ruptures, both prior and following them, pointing to a close interplay between seismic slip and aseismic deformation in specific, well separated segments of the Chilean subduction.
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Martins-Gomes, V., Brito, D., Garambois, S., Dietrich, M., Bordes, C., & Barucq, H. (2023). Seismoelectric wave conversions at an interface: a quantitative comparison between laboratory data and full-waveform modelling. Geophysical Journal International, 235(3), 2992–3011.
Résumé: Seismo-electromagnetic phenomena, electrokinetic in nature, take place whenever a seismic wave propagates in fluid-bearing media, its energy depending mainly on the electrical properties of the fluid and the hydraulic properties of the porous medium. They result from a conversion of mechanical into electromagnetic (EM) energy due to the transient ionic interactions occurring at the pore scale. Two of these phenomena are usually studied: the electric field accompanying seismic waves, and the EM field that travels independently, generated at discontinuities of physicochemical properties in the porous medium. Although the first event is sensitive to physical parameters of the surrounding medium, the second catches information about interfaces in the subsurface, with the resolution of seismic methods, making it very attractive to near surface exploration. In this context, we propose a new experimental setup where both phenomena can be simultaneously studied. At first, we use a porous medium composed of homogeneous water-saturated sand and study the characteristics of the coseismic electric field. Afterwards, a thin layer of Vosges sandstone is inserted into the sand, which allows the study of the EM waves generated at the two closely spaced sand-sandstone interfaces. We record the seismic displacement field at the upper surface of the sand volume using a laser vibrometer, and use stainless steel electrodes buried in the sand to acquire individual electric potentials rather than electric fields, seeking to favour the measurement of the EM interface-generated signals. With the help of direct numerical simulations, we compare experimental measurements and theoretical predictions, based on a well established set of seismoelectric governing equations. In both types of experiments, this comparison shows very good agreements between experimental and numerical waveforms, thus confirming the relevant theory. The electric potential data also show that the EM signals generated at interfaces are clearly recorded at distances of about 10 seismic P wavelengths away from the interface. By contrast, the same events are barely noticeable near the inserted layer when measured using classical electric dipolar arrays.
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Masson, Y., & Virieux, J. (2023). P-SV-wave propagation in heterogeneous media: Velocity-stress distributional finite-difference method. Geophysics, 88(3), T165–T183.
Résumé: We have developed a 2D distributional-finite-difference (DFD) algorithm for modeling the propagation of seismic waves in heterogeneous media in the time domain. We revisit the classic staggered finite-difference algorithm by substituting the standard finite-difference operators with the recently introduced DFD operators with the methodological differences we underline. We find that the DFD operators improve the simulation accuracy while maintaining the simple structure of the finite-difference algorithm. Thanks to its weak formalism, the newly developed algorithm accurately and naturally accounts for the free surface, which is a substantial improvement for finite-difference approaches. Moreover, we develop an efficient factorization for the DFD operators. It limits the computational cost of the proposed algorithm to twice that of the finite-difference algorithm. Numerical examples demonstrate that the extra computational burden is well compensated by the superior accuracy of the DFD operators.
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Massoumi, S., Challamel, N., Lerbet, J., Wautier, A., Nicot, F., & Darve, F. (2023). Shear vibration modes of granular structures: Continuous and discrete approaches. Zamm-Zeitschrift Fur Angewandte Mathematik Und Mechanik, 103(6).
Résumé: This work is dedicated to the study of shear vibration modes of one-dimensional granular microstructured beams using a discrete Cosserat model. The dynamic response of the one-dimensional granular beam (discrete beam) is investigated for various boundary conditions, through the analytical resolution of an exact discrete eigenvalue problem. For an infinite number of grains, the dynamic behavior of the discrete problem converges towards a Bresse-Timoshenko continuum beam model. First, the effective modeling parameters, the constitutive equations and the governing equations of motion are derived in a difference form. For simply supported granular beams, the appearance of pure shear modes of vibration is highlighted (vibration modes without deflection), a phenomenon which is already known in the free vibration of a continuous Bresse-Timoshenko beam problem. The eigenfrequencies of these pure shear modes for the discrete granular beam coincide with the critical frequencies of the discrete system. These pure shear modes may appear for granular beams composed of few grains, which give a physical support of a phenomenon well studied in the literature from a continuum beam model. The eigenfrequencies of the discrete granular beam are also calculated for various boundary conditions, including clamped, hinge and free end boundary conditions. Based on the discrete element method (DEM), several numerical simulations of dynamic tests in some representative examples have been performed. The responses of the numerical approach are accurately compared against the exact results of the analytical solutions based on the difference eigenvalue problem, which illustrates the relevance of the proposed approach.
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Mathiesen, J., Linga, G., Misztal, M., Renard, F., & Le Borgne, T. (2023). Dynamic Fluid Connectivity Controls Solute Dispersion in Multiphase Porous Media Flow. Geophysical Research Letters, 50(16).
Résumé: Solute transport in multiphase flow through porous media plays a central role in many natural systems and geoengineering applications. The interplay between fluid flow and capillary forces leads to transient flow dynamics and phase distributions. However, it is not known how such dynamic flow affects the dispersion of transported species. Here, we use highly resolved numerical simulations of immiscible two-phase flow to investigate dispersion in multiphase flows. We show that repeated activation and deactivation of different flow pathways under the effect of capillary forces accelerates the spreading of solutes compared to single phase flow. We establish the transport laws under dynamic multiphase flows by linking the dispersion coefficient to the Bond number, the ratio of the force driving the flow and the surface tension. Our results determine the controlling factors for solute dispersion in porous media, opening a range of applications for understanding and controlling transport in porous geological systems.
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Matoshko, A., de Leeuw, A., Stoica, M., Mandic, O., Vasiliev, I., Floroiu, A., et al. (2023). The Mio-Pliocene transition in the Dacian Basin (Eastern Paratethys): Paleomagnetism, mollusks, microfauna and sedimentary facies of the Pontian regional stage. Geobios, 77, 45–70.
Résumé: Well-documented, high-resolution sedimentary sections are critical to our understanding of the often eventful evolution of semi-isolated basins that form during the final stages of continent-continent con-vergence, as exemplified by the Mediterranean-Paratethys system. Due to its nearly land-locked position in the Late Miocene, the Mediterranean experienced the renowned Messinian Salinity Crisis. At the same time, the equally restricted Eastern Paratethys to the north-east evolved in a potentially related, but very distinctive way. The events of this period are fully recorded in the sediments deposited during the Pontian regional stage in the Dacian Basin, part of the Eastern Paratethys, which we here investigate in detail in the best available section. The studied interval of the Slanicul de Buzau section is more than 2 km thick and almost continuously exposed. It is analyzed for paleomagnetism, mollusks, microfauna and sedimentary facies. This allows us to refine previous results from nearby but less complete sections, with particular improvements concerning resolution, biostratigraphy and sedimentology. The marine incursion just below the base of the Pontian (6.1 Ma) is shown to significantly predate the early Pontian highstand. The biostratigraphically defined onset of the middle Pontian (6.0 Ma) coincides with the highstand and slightly predates the major regression (5.9-5.6 Ma) for which the middle Pontian is best known. In the here-investigated section, the transgression at the beginning of the late Pontian (5.6 Ma) is followed by a regressive trend culminating between 5.4 and 5.2 Ma around the Mio-Pliocene boundary (5.33 Ma). The late Pontian sedimentation then becomes relatively stable and the fauna gradually transitions (4.8 Ma) into assemblages characteristic for the Dacian stage of the Dacian Basin, while overall significantly diverging from the rest of the Eastern Paratethys. Finally, we discuss several factors that could affect accuracy and applicability of the updated chronostratigraphy, warranting some caution.& COPY; 2023 Published by Elsevier Masson SAS. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
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Matraku, K., Jouanne, F., Dushi, E., Koci, R., Kuka, N., Grandin, R., et al. (2023). The 26 November 2019 Durres earthquake, Albania: coseismic displacements and occurrence of slow slip events in the year following the earthquake. Geophysical Journal International, 234(2), 807–838.
Résumé: Outer Albanides experienced a seismic sequence starting on 21 September 2019, with an M-w 5.6 earthquake, considered a foreshock, and culminated with the main shock on 26 November 2019, followed by a paramount aftershock activity. We propose a model for the coseismic slip distribution using InSAR, permanent, and campaign GNSS measurements. We tested two hypotheses: an earthquake on a thrust plane with the direction N160 degrees and along with a back thrust. By varying the depth and dip angle for the first hypothesis and only the dip angle for the second hypothesis, we concluded the optimal solution is a blind thrust at a 15-km depth dipping eastward 40 degrees, a maximum slip of 1.4 m and an M-w 6.38. A GNSS time-series obtained after 2020 shows two slow slip events (SSEs): the first one is 200 d after the main shock up to 26 d, and the second one is 300 d after the main shock up to 28 d. We tested three hypotheses: SSE along the basement thrust where the main shock has been localized, SSE along the flat formed by the detachment layer of the cover, and SSE along these two faults. We concluded that SSE occurred along the detachment layer or along the two faults.
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Mazzini, I., Cronin, T. M., Gawthorpe, R. L., Collier, R. E. L., de Gelder, G., Golub, A. R., et al. (2023). A new deglacial climate and sea-level record from 20 to 8 ka from IODP381 site M0080, Alkyonides Gulf, eastern Mediterranean. Quaternary Science Reviews, 313.
Résumé: Records of relative sea-level rise for the last deglaciation are mostly limited to coral reef records and geophysical model estimates, but observational data from regions with temperate climates is sparse. We present a new relative climatic and regional sea-level rise record for glacial Termination 1 (Marine Isotope Stages [MIS] 2-1) based on ostracode paleoecology from the upper 8 m of the International Ocean Discovery Program (IODP) Site M0080 collected on Expedition 381, in the Gulf of Alkyonides, eastern Corinth basin of the Mediterranean Sea. Results show a series of major faunal transitions from lacustrine (Ponto-Caspian, Lake Corinth) glacial-age assemblages to fully marine (Mediterranean) interglacial assemblages between 20 and 8 ka. During glacial and early deglacial intervals, the Gulf of Alkyonides was characterized by non-marine lacustrine conditions with episodic sediment input from coastal, saline lake environments. Relatively stable lake shoreline conditions marked by the distinctive Tuberoloxoconcha sp. Existed from -17.5 to 15 ka. During the peak deglacial interval, the Bolling-Allerod (B-A, -15-13.5 ka), rapid sea-level rise is indicated by a fully marine ostracode fauna colonization, which persisted from 13.5 to 7.5 ka (Late Pleistocene-Early to Middle Holocene). The transition from lacustrine to marine environments confirms that during the last glacial maximum (LGM) low sea level (130 – 125 m below present day), the Corinth-Alkyonides depocentres were lacustrine. Marine water breached the shallow Rion and Acheloos-Cape Pappas sills, which today are -50 -60 m deep, separating the Mediterranean and Corinth-Alkyonides system beginning about 15 ka. Based on Alkyonides sedimentation rates, mean rates of sea-level rise during the B-A flooding of the CorinthAlkyonides system are comparable to those obtained from coral reef sea level (SL) records, at least 10 -20 mm yr & DBLBOND;1. Changes in sedimentation and sill depths in this tectonically active region may have played a role in reconnection of the Mediterranean and Corinth/Alkyonides system over a prolonged period. However, the ages and scale of the faunal changes and their clear correspondence with previously published global sea-level curves and the regional sea-level curve based on deglacial land elevation changes predicted by the ICE-7G model suggests the M0080A deglacial is dominated by the glacioeustatic sea-level rise and records details of global climate changes during Termination 1. & COPY; 2023 Elsevier Ltd. All rights reserved.
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Mcbeck, J., Cordonnier, B., Cooke, M., Fattaruso, L., & Renard, F. (2023). Deformation evolves from shear to extensile in rocks due to energy optimization. Communications Earth & Environment, 4(1).
Résumé: Determining how fracture network development leads to macroscopic failure in heterogeneous materials may help estimate the timing of failure in rocks in the upper crust as well as in engineered structures. The proportion of extensile and shear deformation produced by fracture development indicates the appropriate failure criteria to apply, and thus is a key constraint in such an effort. Here, we measure the volume proportion of extensile and shear fractures using the orientation of the fractures that develop in triaxial compression experiments in which fractures are identified using dynamic in situ synchrotron X-ray imaging. The fracture orientations transition from shear to extensile approaching macroscopic, system-size failure. Numerical models suggest that this transition occurs because the fracture networks evolve in order to optimize the total mechanical efficiency of the system. Our results provide a physical interpretation of the empirical internal friction coefficient in rocks. Fracture networks transition from shear to extensile immediately before macroscopic failure in order to optimize the total mechanical efficiency of the system, according to synchrotron observations and modeling of triaxial compression experiments on granite.
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McBeck, J. A., Cordonnier, B., & Renard, F. (2023). The evolving representative elementary volume size in crystalline and granular rocks under triaxial compression approaching macroscopic failure. Geophysical Journal International, 232(3), 1898–1913.
Résumé: Determining the size of the representative elementary volume (REV) for properties of fracture networks, such as porosity and permeability, is critical to robust upscaling of properties measured in the laboratory to crustal systems. Although fractured and damaged rock may have higher porosity and permeability than more intact rock, and thus exert a dominant influence on fluid flow, mechanical stability and seismic properties, many of the analyses that have constrained the REV size in geological materials have used intact rock. The REV size is expected to evolve as fracture networks propagate and coalesce, particularly when fracture development becomes correlated and the growth of one fracture influences the growth of another fracture. As fractures propagate and open with increasing differential stress, the REV size may increase to accommodate the larger fractures. The REV size may also increase as a consequence of the increasing heterogeneity of the fracture network, as many smaller fractures coalesce into fewer and longer fractures, and some smaller fractures stop growing. To quantify the evolving heterogeneity of fracture networks, we track the REV size of the porosity throughout eleven triaxial compression experiments under confining stresses of 5-35 MPa. Acquiring X-ray tomography scans after each increase of differential stress provides the evolving 3-D fracture network in four rock types: Carrara marble, Westerly granite, quartz monzonite and Fontainebleau sandstone. In contrast to expectations, the REV size does not systematically increase toward macroscopic failure in all of the experiments. Only one experiment on sandstone experiences a systematic increase in REV size because this rock contains significant porosity preceding loading, and it subsequently develops a localized fracture network that spans the core. The REV size may not systematically increase in most of the experiments because the highly heterogeneous porosity distributions cause the REV to become larger than the core. Consistent with this idea, when the rock does not have a REV, the fractures tend to be longer, thicker, more volumetric, and closer together than when the rock hosts a REV. Our estimates of the REV for the porosity of the sandstone are similar to previous work: about two to four times the mean grain diameter, or 0.5-1 mm. This agreement with previous work and the <15 per cent change in the REV size in two of the sandstone experiments suggests that when a system composed of sandstone does not host a localized, system-spanning fracture network, estimates of the REV derived from intact sandstone may be similar to estimates derived from damaged sandstone. Using the existing REV estimates derived from intact sandstone to simulations with more damaged crust, such as the damage zone adjacent to large crustal faults, will allow numerical models to robustly simulate increasingly complex crustal systems.
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Mehta, N., Vantelon, D., Gaetan, J., Fernandez-Martinez, A., Delbes, L., Travert, C., et al. (2023). Calcium speciation and coordination environment in intracellular amorphous calcium carbonate (ACC) formed by cyanobacteria. Chemical Geology, 641.
Résumé: An increasing number of bacteria has been shown to form intracellular amorphous calcium carbonates (ACC), as previously observed for biomineralizing eukaryotes. Yet, the short-range order of these bacterial intracellular ACC remains largely unexplored. Because ACC in bacteria is easily lost upon sample preparation, the use of in situ techniques is required to probe ACC within intact cells at the atomic scale. Here, we show the application of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies to study the calcium (Ca) speciation and coordination environment in intact cells of diverse ACC-forming cyanobacteria. Our results show that XANES was effective in detecting ACC in intact cells. Between 60 and 85% of the total Ca in ACC-forming cyanobacteria strains is contained in the ACC phase and the rest in a single phase or a mixture of amorphous phases, possibly Ca complexed by organic molecules. Moreover, the short-range order of cyanobacterial ACC was different from eukaryotic ACC. This short-range order was similar to monohydrocalcite. These findings shed light on the fate of cyanobacterial ACC and the role of ACC-forming cyanobacteria in the Ca biogeochemical cycle.
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Mei, J., Ma, G., Liu, J., Nicot, F., & Zhou, W. (2023). Modeling shear-induced solid-liquid transition of granular materials using persistent homology. Journal Of The Mechanics And Physics Of Solids, 176.
Résumé: This paper investigates the transition between the solid and liquid phases of sheared granular materials from the perspective of the contact network. Tools from persistent homology are employed to quantify the dynamics of contact network during the solid-liquid transition from a global perspective, and two important topological invariants, i.e., components and loops, are mainly investigated from discrete numerical simulations. The highly heterogeneous composition of the contact network is revealed, and a rationale partition threshold for distinguishing between strong and weak contact subnetworks can be determined through the emergence and death of these topological invariants. During the shearing process, we recognize mechanical precursors forecasting the occurrence of solid-liquid transition when the assembly is still stable. Further-more, we provide the panorama of the solid-liquid transition from the evolution of contact network and its homology groups. Finally, this study suggests that the persistent homology method is capable of quantitatively bridging the microscopic dynamics with macroscopic re-sponses through the contact network, which paves an efficient way to further include the evo-lution of the contact network in the constitutive modeling of granular materials.
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Melis, R., Maheo, G., Gardien, V., Jame, P., Bonjour, E., Bhandari, B., et al. (2023). When rainfall trapped in fluid inclusion restores the relief of an orogen: Insights from the Cenozoic Himalayas. Earth And Planetary Science Letters, 613.
Résumé: The involvement of meteoric water in orogens dynamics through surface processes is well known as for example in the Himalayas where erosion, resulting of the interplay between climate and tectonics shapes the most spectacular landscapes on the planet. But what about more internal and deepest surface fluid infiltration? Here we report analysis of the delta 18O(water) and delta D(water) of extracted water from fluid inclusions hosted into Cenozoic quartz veins sampled in the core of the Himalayan range, near the Main Central Thrust and the South Tibetan Detachment. Isotopic and microthermometric values suggest a meteoric origin for the fluids trapped in the quartz of syn-to post-kinematic veins formed between 10 to 20 km depth. Moreover, the isotopic compositions obtained in this study on quartz fluid inclusions water collected along a transect across the Himalayan range evolved with the topography in a similar manner than the modern meteoric water. Considering the age of formation of the quartz veins between 18 and 12 Ma, we deduce that the morphology of the Himalayan topographic front was already shaped during the Miocene but located further north. (c) 2023 Elsevier B.V. All rights reserved.
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Meziane, A., Blanloeuil, P., Nouira, D., Baillet, L., & Massi, F. (2023). Numerical analysis of a one-dimensional nonlinear wave scattering at a contact interface with damageable adhesion and unilateral contact. Wave Motion, 122.
Résumé: The nonlinear scattering of a longitudinal harmonic plane wave, induced by a contact interface, is investigated numerically, using a model that combines damageable adhesion and unilateral contact. This novel approach captures the smooth transition between a perfectly bonded interface and a disbonded clapping interface, also referred to as a kissing bond. This is achieved through an RCCM (Raous, Cangemi, Cocu and Monerie) contact law, where exceedance of the elastic limit in tension triggers the generation of damage and a progressive reduction of the tensile interface stiffness until zero, i.e. equivalent to unilateral contact. This RCCM law is implemented in a 1D finite difference model where the contact interface is defined between a semi-infinite domain and a rigid wall. Since the nonlinear scattering is only dependent on the interface law, damping in the propagation medium is not considered. The reflected wave is post-processed to obtain the nonlinear signature of the interface through the evolution of the normalized DC, fundamental and second harmonic components, as a function of the normalized frequency and the interface load. This analysis provides useful insights for understanding the interface response and shows that the nonlinear signature contains information on the different parameters of the RCCM law, as well as on the damage state of the interface. These encouraging results provide insight and guidance for the non-destructive evaluation of contact interfaces and adhesive joints using non-linear acoustics. & COPY; 2023 Elsevier B.V. All rights reserved.
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Michailos, K., Hetenyi, G., Scarponi, M., Stipcevic, J., Bianchi, I., Bonatto, L., et al. (2023). Moho depths beneath the European Alps: a homogeneously processed map and receiver functions database. Earth System Science Data, 15(5), 2117–2138.
Résumé: We use seismic waveform data from the AlpArray Seismic Network and three other temporary seismic networks, to perform receiver function (RF) calculations and time-to-depth migration to update the knowledge of the Moho discontinuity beneath the broader European Alps. In particular, we set up a homogeneous processing scheme to compute RFs using the time-domain iterative deconvolution method and apply consistent quality control to yield 112 205 high-quality RFs. We then perform time-to-depth migration in a newly implemented 3D spherical coordinate system using a European-scale reference P and S wave velocity model. This approach, together with the dense data coverage, provide us with a 3D migrated volume, from which we present migrated profiles that reflect the first-order crustal thickness structure. We create a detailed Moho map by manually picking the discontinuity in a set of orthogonal profiles covering the entire area. We make the RF dataset, the software for the entire processing workflow, as well as the Moho map, openly available; these open-access datasets and results will allow other researchers to build on the current study.
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Michalchuk, S. P., Zertani, S., Renard, F., Fusseis, F., Chogani, A., Plumper, O., et al. (2023). Dynamic Evolution of Porosity in Lower-Crustal Faults During the Earthquake Cycle. Journal Of Geophysical Research-Solid Earth, 128(8).
Résumé: Earthquake-induced fracturing of the dry and strong lower crust can transiently increase permeability for fluids to flow and trigger metamorphic and rheological transformations. However, little is known about the porosity that facilitates these transformations. We analyzed microstructures that have recorded the mechanisms generating porosity in the lower crust from a pristine pseudotachylyte (solidified earthquake-derived frictional melt) and a mylonitized pseudotachylyte from Lofoten, Norway to understand the evolution of fluid pathways from the coseismic to the post- and interseismic stages of the earthquake cycle. Porosity is dispersed and poorly interconnected within the pseudotachylyte vein (0.14 vol%), with a noticeably increased amount along garnet grain boundaries (0.25-0.41 vol%). This porosity formed due to a net negative volume change at the grain boundary when garnet overgrows the pseudotachylyte matrix. Efficient healing of the damage zone by fluid-assisted growth of feldspar neoblasts resulted in the preservation of only a few but relatively large interconnected pores along coseismic fractures (0.03 vol% porosity). In contrast, porosity in the mylonitized pseudotachylyte is dramatically reduced (0.02 vol% overall), because of the efficient precipitation of phases (amphibole, biotite and feldspars) into transient pores during grain-size sensitive creep. Porosity reduction on the order of >85% may be a contributing factor in shear zone hardening, potentially leading to the development of new pseudotachylytes overprinting the mylonites. Our results show that earthquake-induced rheological weakening of the lower crust is intermittent and occurs when a fluid can infiltrate a transiently permeable shear zone, thereby facilitating diffusive mass transfer and creep. Plain Language Summary Earthquakes create fractures and increase the porosity in crustal rocks. These fractures can help transport fluids to newly accessible regions in the crust, which in turn may kickstart metamorphic reactions, and potentially alter the rheology. However, very little is known about the mechanisms, the microstructural context, and the morphology of this increased porosity. We analyzed ancient earthquake-generated frictional melts (pseudotachylytes) and their immediate damage zone in the host rock, as well as plasticly deformed pseudotachylytes, that have since been exhumed from depth and are now exposed at the surface in Lofoten, Norway. We analyzed these rocks to determine the processes that create porosity and how this porosity evolves with increasing plastic deformation. The pseudotachylyte hosts more porosity than the damage zone immediately flanking the vein, in particular there is a high concentration of porosity around garnets. We interpret this porosity to have formed as a result of the metamorphic growth of garnet. Much of the fracture-related porosity created during the initial earthquake has been efficiently sealed. Porosity is greatly reduced in the sheared pseudotachylytes because of solution-precipitation processes that operated during ductile deformation. Porosity reduction may reflect fluid consumption, leading to shear zone hardening and possibly new pseudotachylyte formation.
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Migdisova, N. A., Sushchevskaya, N. M., Portnyagin, M. V., Shishkina, T. A., Kuzmin, D. V., & Batanova, V. G. (2023). Composition of Phenocrysts in Lamproites of Gaussberg Volcano, East Antarctica. Geochemistry International, 61(9), 911–936.
Résumé: This paper presents numerous new data on the geochemical composition of olivine, clinopyroxene, and leucite phenocrysts, as well as spinel inclusions in olivine and quench glass from lamproites of Gaussberg volcano (East Antarctica). Most of the olivine phenocrysts in the Gaussberg lamproites are high Mg varieties (Fo(89-91)) with elevated Ni contents (up to 4900 ppm) and high Ni/Co ratios. According to data of about 320 clinopyroxene analyses, two groups of diopsidic phenocrysts have been established. Group I consists mainly of high-Mg varieties (Mg#>80), while group II clinopyroxenes are less magnesian (Mg# 52-80). The main difference between the clinopyroxenes of the two groups is the elevated contents of Al2O3, FeO and reduced TiO2, Cr2O3, and NiO in the compositions of group II compared to group I, as well as different contents of trace elements, which may reflect their crystallization from different types of primary melts. According to the study of similar to 550 grains of leucite phenocrysts in the Gaussberg lamproites, it was shown that they correspond to the ideal stoichiometry of leucite K[AlSi2O6] and are enriched in Na2O (0.05-0.35 wt %), but depleted in K2O (19.9-20.9 wt %) compared to leucites from lamproites of other provinces. The BaO content reaches 0.3 wt %, SrO -0.04 wt %. The iron content in most leucite phenocrysts varies within 0.7-1.2 wt % Fe2O3, but some grains have the low Fe2O3 contents (<0.5 wt %). In leucite microlites of the groundmass and rims of phenocrysts, the Fe2O3 content can reach 2.4 wt %, which may indicate more oxidized conditions at lava eruption. Based on the study of natural samples, existing experimental data and numerical models, the order and conditions of crystallization of the Gaussberg lamproites were obtained. Crystallization proceeded in the following order: chromian spinel. chromian spinel + olivine -> olivine + leucite (+/- chromian spinel) -> olivine + leucite + clinopyroxene (+/- chromian spinel). The near-liquidus assemblage represented by high-Mg olivine phenocrysts with inclusions of Cr-spinel was formed in the temperature range from 1180 to 1250 degrees C. Further crystallization of the melt with the formation of an association of olivine+leucite+clinopyroxene phenocrysts could occur at pressures below 2 GPa and temperatures of 1070-1180 degrees C, corresponding to the presence of water in the magmatic system. Estimates of the redox conditions of crystallization of lamproites obtained using different oxybarometers vary in a wide range from QFM-0.5 to QFM+2.3. The elevated Ni contents in liquidus olivines of Gaussberg indicate the high nickel contents in the source. It is shown that the formation of ultra-alkaline magmas in the Gaussberg volcano area is likely related to melting of the continental lithosphere, which was heterogeneous and included both the peridotite mantle and hydrous pyroxenite fragments.
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Milesi, G., Valla, P. G., Munch, P., & Huyghe, D. (2023). Tectono-geomorphological evolution of the Eastern Pyrenees: Insights from thermo-kinematic modeling. Tectonophysics, 866.
Résumé: Constraining the tectono-geomorphological evolution of the Pyrenees is still a major challenge, especially in the Eastern Pyrenees where late Neogene exhumation history and topographic evolution appear contrasted and have been debated. In this study, we performed thermo-kinematic (Pecube) modeling using a relatively dense spatial compilation of previously-published low-temperature thermochronological data for the Eastern Pyrenees, and quantified the late-Neogene exhumation history based on different topographic evolution models reconstructed from literature constraints. Our modeling outcomes suggest a major decrease in the regional exhumation rate between 37 and 35 Ma, associated to an early-end contractional tectonics for the Eastern Pyrenees. Two main periods of the Tet fault normal activity have been characterized, with the existence of pluri-kilometric (2-3 km) post-Oligocene-Miocene displacement along the western segment of the Tet fault. The different topographic evolution models show relatively similar results for the regional exhumation since ca. 35 Ma and for the most recent (mid to late-Miocene) tectonic event recorded along the Tet fault. Conversely, inversion results obtained for pre-35 Ma regional exhumation rates, and more importantly for the Oligocene-Miocene activity of the Tet fault appear contrasted between the investigated topographic scenarios. Overall, this study confirmed a mid to late Miocene significant extensional tectonic event for the Eastern Pyrenees, which may have had a non -negligible role in late-stage relief evolution for this part of the orogen. However, deciphering the long-term evolution of topographic relief through thermo-kinematic modeling appears still challenging for slowly -exhuming mountain ranges given the limited resolution of low-temperature thermochronological data to topo-graphic changes.
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Milyukova, A., Skoblenko, A., Dilek, Y., Wang, K. - L., Batanova, V., & Degtyarev, K. E. (2023). Geochemistry, mineral chemistry and Re-Os isotopes of refractory peridotites of the North Balkhash ophiolite zone in the West Central Asian Orogenic Belt (Central Kazakhstan): multi-stage melt evolution of a late Precambrian forearc mantle. Journal Of The Geological Society, 180(6).
Résumé: In this study we report on the petrography, major and trace element and mineral chemistry, platinum-group elements and Re-Os isotope systematics of depleted ultramafic rock suites from the Itmurundy Block in the North Balkhash ophiolite zone in Kazakhstan. Represented mainly by variably serpentinized harzburgites and dunites, our samples are characterized by low whole-rock Al2O3 (0.33-0.86 wt%), CaO (0.51-0.86 wt%) and Na2O (0.07-0.25 wt%) concentrations, and high-Mg olivine (Fo = 91-92) and orthopyroxene (Mg# = 92-93) contents, together with moderately high spinel Cr-numbers (Cr# = 63-68). They are depleted in incompatible elements (sigma REE, Nb, Sc) and enriched in compatible elements, such as Cr (up to 2817 ppm) and Ni (up to 2327 ppm), representing highly refractory mantle residues derived from a forearc mantle wedge. They underwent 19-23% hydrous partial melting to produce boninitic melts.Os- 187/Os-188 values vary from 0.1202 to 0.12599, and Re-187/Os-188 ratios from 0.230 to 0.316. The Re-Os model ages (T-MA) and maximum Re depletion model age (T-RD) were calculated based on the obtained data. Re-Os isotope systematics suggests that the analysed peridotites formed in two stages: a first stage around 1.5 Ga and a later stage around 668-589 Ma.
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Moczo, P., Kristek, J., Kristekova, M., Valovcan, J., Galis, M., & Gregor, D. (2023). Material Interface in the Finite-Difference Modeling: A Fundamental View. Bulletin Of The Seismological Society Of America, 113(1), 281–296.
Résumé: By analyzing the equations of motion and constitutive relations in the wavenumber domain, we gain important insight into attributes determining the accuracy of finite-difference (FD) schemes. We present heterogeneous formulations of the equations of motion and constit-utive relations for four configurations of a wavefield in an elastic isotropic medium. We Fourier-transform the entire equations to the wavenumber domain. Subsequently, we apply the band-limited inverse Fourier transform back to the space domain. We analyze conse-quences of spatial discretization and wavenumber band limitation. The heterogeneity of the medium and the Nyquist-wavenumber band limitation of the entire equations has important implications for an FD modeling: The grid representation of the heterogeneous medium must be limited by the Nyquist wavenumber. The wavenumber band limitation replaces spatial derivatives both in the homogeneous medium and across a material inter-face by continuous spatial convolutions. The latter means that the wavenumber band limi-tation removes discontinuities of the spatial derivatives of the particle velocity and stress at the material interface. This allows to apply proper FD operators across material interfaces. A wavenumber band-limited heterogeneous formulation of the equations of motion and constitutive relations is the general condition for a heterogeneous FD scheme.
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Molina-Ormazabal, D., Ampuero, J. - P., & Tassara, A. (2023). Diverse slip behaviour of velocity-weakening fault barriers. Nature Geoscience, .
Résumé: Seismic barriers are fault portions that promote earthquake rupture arrest and fault segmentation. Despite their fundamental role in controlling the maximum magnitude of earthquakes, the nature of seismic barriers is still uncertain. A common interpretation of barriers as having velocity-strengthening friction-steady-state friction that increases with increasing slip velocity-is only partially consistent with the thermal control of friction observed in laboratory experiments, which implies that most relevant materials in subduction channels are velocity-weakening at seismogenic depths. Here we examine the possibility of velocity-weakening barriers by conducting earthquake cycle simulations along a velocity-weakening megathrust segmented by lateral variations of frictional properties and normal stress. We show that velocity-weakening fault segments display a wide range of behaviours, including permanent barrier behaviour. They can be locked during long periods and release their slip deficit either seismically or aseismically. We quantify the efficiency of velocity-weakening barriers in arresting ruptures using a non-dimensional parameter based on fracture mechanics theory that can be constrained by observations on natural faults. Our results provide a theoretical framework that could improve physics-based seismic hazard assessment. Velocity-weakening seismic barriers in subduction zones display a range of behaviours consistent with geologic structural control on earthquake seismicity, according to earthquake cycle simulations along a megathrust.
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Monasterio-Guillot, L., Borsoi, G., & Otero, J. (2023). Advances in Nanolime and Other Nanomaterials for Built Heritage Conservation. Materials, 16(4).
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Montabert, A., Giry, C., Schraen, C. L., Lepine, J., Choueiri, C., Mercerat, E. D., et al. (2023). An Open Database to Evaluate the Fundamental Frequency of Historical Masonry Towers through Empirical and Physics-Based Formulations. Buildings, 13(9).
Résumé: The fundamental frequency plays a primary role in the dynamic assessment of Cultural Heritage towers. Local and global features may impact its value: geometric, material features, interaction with the soil and adjacent buildings, aging, the construction phase, and repairs. A database is assembled to study the relationship between the fundamental frequency and the slender masonry structure features. Empirical and physics-based approaches were developed to assess the fundamental frequency from different sources of information. A Rayleigh-Ritz approach is proposed and compared with a 3D finite element model. A sensitivity analysis is then performed to quantify the contribution of each feature. As expected, it is shown that the height of the tower contributes the most to the fundamental frequency. The other tower features have a second-order impact on both the fundamental frequency and the mode shape. A comparison between the different approaches shows that the Rayleigh-Ritz drastically minimizes the difference between numerical and experimental frequencies when all information is available. Empirical relations are a good compromise when less information is available.
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Montes-Hernandez, G., Feugueur, L., Vernier, C., Van Driessche, A. E. S., & Renard, F. (2023). Efficient removal of antibiotics from water via aqueous portlandite carbonation. Journal Of Water Process Engineering, 51.
Résumé: Current wastewater treatment technologies struggle to remove antibiotics from wastewaters, leading to contamination of surface and groundwater. Therefore, more effective and efficient processes for removing an-tibiotics from water are needed. The present study reports for the first time that three widely used antibiotics (amoxicillin, ceftriaxone, cefazoline) can be successfully removed from water under ambient conditions by using aqueous carbonation of portlandite. Breakthrough curves acquired from flow-through experiments and their respective removal isotherms were mainly used to determine quantitative equilibrium parameters. In this way, the removal of antibiotics using aqueous portlandite carbonation is very efficient for amoxicillin (9.5 mg/g), followed by cefazoline (4.3 mg/g) and ceftriaxone (2.7 mg/g). In a comparison perspective, nanomagnetite-interfacial Fenton reaction is more effective in removing amoxicillin (76.5 mg/g); however, the process is slower and chemically more complex. However, both investigated methods offer promising results at the labo-ratory scale and are technically feasible to be implemented in conventional and/or advanced wastewater treatment plants.
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Moreau, L., Seydoux, L., Weiss, J., & Campillo, M. (2023). Analysis of microseismicity in sea ice with deep learning and Bayesian inference: application to high-resolution thickness monitoring. Cryosphere, 17(3), 1327–1341.
Résumé: In the perspective of an upcoming seasonally ice-free Arctic, understanding the dynamics of sea ice in the changing climate is a major challenge in oceanography and climatology. In particular, the new generation of sea ice models will require fine parameterization of sea ice thickness and rheology. With the rapidly evolving state of sea ice, achieving better accuracy, as well as finer temporal and spatial resolutions of its thickness, will set new monitoring standards, with major scientific and geopolitical implications. Recent studies have shown the potential of passive seismology to monitor the thickness, density and elastic properties of sea ice with significantly reduced logistical constraints. For example, human intervention is no longer required, except to install and uninstall the geophones. Building on this approach, we introduce a methodology for estimating sea ice thickness with high spatial and temporal resolutions from the analysis of icequake waveforms. This methodology is based on a deep convolutional neural network for automatic clustering of the ambient seismicity recorded on sea ice, combined with a Bayesian inversion of the clustered waveforms. By applying this approach to seismic data recorded in March 2019 on fast ice in the Van Mijen Fjord (Svalbard), we observe the spatial clustering of icequake sources along the shoreline of the fjord. The ice thickness is shown to follow an increasing trend that is consistent with the evolution of temperatures during the 4 weeks of data recording. Comparing the energy of the icequakes with that of artificial seismic sources, we were able to derive a power law of icequake energy and to relate this energy to the size of the cracks that generate the icequakes.
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Mouchon, C., Frank, W. B. B., Radiguet, M., Poli, P., & Cotte, N. (2023). Subdaily Slow Fault Slip Dynamics Captured by Low-Frequency Earthquakes. Agu Advances, 4(4).
Résumé: Geodetic positioning is the geophysical record of reference for slow slip events, but typical daily solutions limit studies of the evolution of slow slip to its long-term dynamics. Accompanying seismic low-frequency earthquakes located precisely in time and space provide an opportunity to image slow slip dynamics at subdaily time scales. Here we show that a high-resolution time history of low-frequency earthquake fault slip alone can reproduce the geodetic record of slow slip that we observe to be dominated by subdaily fault slip dynamics. However, a simple linear model cannot accommodate the complex dynamics present throughout the slow slip cycle, and an analysis of different phases of the slow slip cycle shows that the ratio of geodetic to seismic fault slip varies as a function of time. This suggests that the low-frequency earthquake source region saturates as slow slip grows in moment and area. We propose that rheological heterogeneities at the plate boundary associated with low-frequency earthquakes do not play a significant role in the slow slip rupture process, thus implying that their activity is incidental to the driving aseismic slip.Plain Language Summary Slow slip events can be observed in many subduction zones where they play an important role in the earthquake cycle. Decades after their discovery, slow slip events are now captured routinely in geodetic datasets with slip dynamics occurring over a broad range of time scales. Using high-time resolution seismological observations together with the geodetic record allows us to go beyond the coarse daily GNSS sampling rate to image slow slip dynamics at short time scales. Here we use the temporal evolution of seismic slip produced by low-frequency earthquakes to study the subdaily dynamics of a slow slip event cycle, reproducing the geodetic record of slow slip using only seismological observations. We develop a simple model where long-term loading is in competition with the intermittent release of stress tied to the seismic slip of low-frequency earthquakes. We show the full slow slip cycle is driven by bursts of slip at subdaily time scales that low-frequency earthquake events witness only in their immediate source region. This result implies that the low-frequency earthquake rupture process is incidental to slow fault slip and does not play a major role in the slow slip cycle.
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Moutote, L., Itoh, Y., Lengline, O., Duputel, Z., & Socquet, A. (2023). Evidence of a Transient Aseismic Slip Driving the 2017 Valparaiso Earthquake Sequence, From Foreshocks to Aftershocks. Journal Of Geophysical Research-Solid Earth, 128(9).
Résumé: Following laboratory experiments and friction theory, slow slip events and seismicity rate accelerations observed before mainshocks are sometimes interpreted as evidence of a nucleation phase. However, such precursory observations still remain scarce and are associated with different time and length scales, raising doubts about their actual preparatory nature. We study the 2017 Valparaiso Mw = 6.9 earthquake, which was preceded by aseismic slip accompanied by an intense seismicity, suspected to reflect its nucleation phase. We complement previous observations, which have focused only on precursory activity, with a continuous investigation of seismic and aseismic processes from the foreshock sequence to the post-mainshock phase. By building a high-resolution earthquake catalog and searching for anomalous seismicity rate increases compared to aftershock triggering models, we highlight an over-productive seismicity starting within the foreshock sequence and persisting several days after the mainshock. Using repeating earthquakes and high-rate GPS observations, we highlight a transient aseismic perturbation starting 1-day before the first foreshock and continuing after the mainshock. The estimated slip rate over time is lightly impacted by large magnitude earthquakes and does not accelerate toward the mainshock. Therefore, the unusual seismic and aseismic activity observed during the 2017 Valparaiso sequence might be interpreted as the result of a slow slip event starting before the mainshock and continuing beyond it. Rather than pointing to a possible nucleation phase of the 2017 Valparaiso mainshock, the identified slow slip event acts as an aseismic loading of nearby faults, increasing the seismic activity, and thus the likelihood of a large rupture. Both laboratory experiments and friction theory show that earthquakes do not begin abruptly but are preceded by an accelerating slip associated with a seismicity increase. On the field, however, such precursory observations still remain scarce and are associated with different characteristic time and length scales, raising doubts that they actually reflect the same nucleation phenomena. We study the 2017 Valparaiso M = 6.9 earthquake, which was preceded by both a slow slip and an intense seismicity suspected to reflect such nucleation phase. We complement previous studies, that have focused only on precursory activity, with a continuous investigation of seismic and slow slip before and after the mainshock. Using refined earthquake detection tools, we highlight a seismicity excess starting before and persisting several days after the mainshock. Using repeating earthquakes and high-resolution GPS, we show that the slow slip does not accelerate toward the mainshock, but continues after it. Therefore, rather than pointing to a possible accelerating nucleation phase of the Valparaiso mainshock, we suggest that the slow slip drives an enhanced seismic activity that is not mainshock-directed. Within such slow-slip driven seismicity, the probability of triggering a large earthquake (subsequently considered as the mainshock) is increased. We use a high resolution seismic catalog and GPS to investigate seismic and aseismic process before and after the Valparaiso mainshockAn unusually high seismicity and a slow slip event is continuously observed from the foreshock sequence up to days after the mainshockRather than a nucleation phase of the mainshock, the slow slip event acts as an aseismic loading of nearby faults during the entire sequence
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Moya, A., Giraud, F., Molinier, V., Perrette, Y., Charlet, L., Van Driessche, A., et al. (2023). Exploring carbonate rock wettability across scales: Role of (bio)minerals. Journal Of Colloid And Interface Science, 642, 747–756.
Résumé: Hypothesis: The wettability of carbonate rocks is expected to be affected by the organic components of biominerals which are complex, nanostructured organo-mineral assemblages. Elucidating the nanoscale mechanisms driving the wettability of solid surfaces will enable a better understanding of the role of biominerals in the wetting properties of carbonate rocks to control various geological, environmental and industrial processes.Experiments: Using Atomic Force Microscopy and Spectroscopy (AFM/AFS) we probed the wettability properties of carbonate rocks with different amounts of organic material. The adhesion properties of two types of limestones were determined in liquid environments at different length scales (nm to mm) using functionalized tips with different chemical groups to determine the extent of surface hydrophobic and hydrophilic organo-mineral interactions.Findings: We observed homogeneous hydrophobic areas at length scales below < 5lm. The origin of this hydrophobicity is linked to the presence of organics, whose amount and spatial distribution depend on the rock composition. Specifically, our results reveal that the biogenic vs non-biogenic origin of the min-eral grains is the main rock property controlling the wettability of the solid surface. Overall, our method-ology offers a multi-scale approach to unravel the role that organic moieties and biominerals play in controlling the wettability of rock-water interfaces.(c) 2023 Elsevier Inc. All rights reserved.
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Muir, R. A., Whitehead, B. A., New, T., Stevens, V., Macey, P. H., Groenewald, C. A., et al. (2023). Exceptional Scarp Preservation in SW Namibia Reveals Geological Controls on Large Magnitude Intraplate Seismicity in Southern Africa. Tectonics, 42(4).
Résumé: Four previously unrecognized neotectonic fault scarps in southwest Namibia are described. These relatively straight, simple but segmented structures are 16-80 km long and have measured vertical separations of 0.7-10.2 m. We estimate that each is capable of producing earthquakes of M-w 6.4 or greater, indicating that large earthquakes may occur despite limited cumulative displacement. There is strong evidence that some of these scarps were formed by repeated earthquakes. Comparison with aeromagnetic and geological maps reveal that the normal faults reactivate major crustal weaknesses that are orientated north-south and northwest-southeast and perpendicular to the local gravitational potential energy gradient. The presence of these structures in an area with a limited record of instrumental seismicity suggests that the M-max of this region may be much larger than generally assumed. They highlight the necessity of incorporating information from fault studies into probabilistic seismic hazard assessments in this region, in a similar way to other stable continental regions such as Australia. The fact that such major structures have gone hitherto unrecorded suggests significant further research is needed to characterize these sources of hazard. The identification of an apparent cluster of large magnitude neotectonic earthquakes in the area may be related to the exceptional preservation potential of scarps rather than indicating an area of comparatively rapid deformation. If this interpretation is correct, then these scarps represent an important indication of the potential seismic hazard across the region, and the occurrence of infrequent large-magnitude seismicity on similar structures should be considered throughout southwestern Africa.
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Muzellec, T., Lesage, P., Caudron, C., & Got, J. - L. (2023). Migration of Mechanical Perturbations Estimated by Seismic Coda Wave Interferometry During the 2018 Pre-Eruptive Period at Kilauea Volcano, Hawaii. Journal Of Geophysical Research-Solid Earth, 128(8).
Résumé: We use seismic ambient noise correlation and coda wave interferometry to estimate velocity variations at high temporal resolution, during the pre-eruptive period and the onset of the 2018 eruption of Kilauea volcano. A progressive velocity increase is observed from March to the end of April. It is followed by rapid decrease starting a few days before the onset of the East Rift Zone (ERZ) eruption and then by sharp velocity drop when the eruption started. The change of trend from velocity increase to decrease is progressively delayed by a few days from the summit caldera toward the ERZ. The location of the velocity perturbations shows a migration of the sources of velocity changes from the summit caldera toward the ERZ before the eruption. Using a model of pressure source, we show that the simultaneous caldera inflation and velocity increase probably result from an anisotropic distribution of fault and crack orientations. The velocity decrease could be due to damaging processes above the shallow reservoir and to plastic deformations around the caldera. We introduce a forward model of rock damage associated with the volcano-tectonic seismicity to calculate the velocity decrease. The good agreement between the calculated and the observed velocity variations shows that a large part of the velocity decrease results from damage of the medium. The delayed onsets of velocity decrease and the source migration of velocity perturbations are probably related to progressive fault openings in the Southern and Eastern parts of the caldera and to magma transfer toward the ERZ.
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Nader, A. A., Albaric, J., Steinmann, M., Hibert, C., Malet, J. - P., Sue, C., et al. (2023). Machine learning prediction of groundwater heights from passive seismic wavefield. Geophysical Journal International, 234(3), 1807–1818.
Résumé: Most of water reservoirs are underground and therefore challenging to monitor. This is particularly the case of karst aquifers which knowledge is mostly based on sparse spatial and temporal observations. In this study, we propose a new approach, based on a supervised machine learning algorithm, the Random Forests, and continuous seismic noise records, that allows the prediction of the underground river water height. The study site is a karst aquifer in the Jura Mountains (France). An underground river is accessible through an artificial shaft and is instrumented by a hydrological probe. The seismic noise generated by the river is recorded by two broadband seismometers, located underground (20 m depth) and at the surface. The algorithm succeeds in predicting water height thanks to signal energy features. Even weak river-induced noise such as recorded at the surface can be detected and used by the algorithm. Its efficiency, expressed by the Nash-Sutcliffe criterion, is above 95 per cent and 53 per cent for data from the underground and surface seismic stations, respectively.
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Nataf, H. - C. (2023). Response to Comment on “Tidally Synchronized Solar Dynamo: A Rebuttal”. Solar Physics, 298(3).
Résumé: The core of my article (Nataf in Solar Phys. 297, 107, 2022) was about a flaw in the reasoning used by Stefani, Giesecke, and Weier (Solar Phys. 294, 60, 2019) to demonstrate that the similar to 11-year Schwabe cycle is “clocked”. To give some background and point out other difficulties, I displayed tidal signals built from a very simple four-planet model. Nicola Scafetta criticizes this simplified tidal model because it assumes circular orbits. This is correct. It seems that he did not notice that I referred to the article of Okal and Anderson (Nature, 253, 511, 1975), who were the first to construct a tidal model that takes into account the actual orbits of these four planets. His comment gives me the opportunity to be more explicit on this question. The main conclusion of my original article does not change: no support for a planetary influence on solar cycles.
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Nicot, F., Wang, X., Wautier, A., Wan, R., & Darve, F. (2023). Shear banding as a dissipative structure from a thermodynamic viewpoint. Journal Of The Mechanics And Physics Of Solids, 179.
Résumé: Granular materials are now known to be an illustration of complex materials as they display emergent macroscopic properties when loaded. An initially homogenous response can bifurcate into a heterogeneous one with the appearance of a rich variety of structured kinematical patterns. The shear banding that ensues illustrates a symmetry-breaking transition with multiple choices of macroscopic behaviours, a common feature of dynamical complex systems. Even though the phenomenon has been studied for decades, this regime transition remains mostly mysterious in geomaterials, with no convincing arguments that could link it to the underlying microscopic mechanisms. The paper investigates this issue by invoking the fundamental minimum entropy production theorem established by Prigogine in the past century to seek any connection with the second-order work theory in the mechanics of failure. A general equation linking the derivatives of the entropy of a mechanical system to the second-order work is thus inferred, which leads to a thermodynamic interpretation of bifurcations in the failure behaviour of granular materials under a given loading. This is verified through discrete element simulations that highlight the fundamental role played by the elastic energy stored within a granular material before a bifurcation occurs, which also corresponds to a minimization of the entropy production. The analysis suggests a new interpretation of the intriguing shear banding phenomenon as a bifurcation with the emergence of ordered dissipative structures germane to nonequilibrium thermodynamics of open systems.
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Nouibat, A., Brossier, R., Stehly, L., Cao, J., & Paul, A. (2023). Ambient-Noise Wave-Equation Tomography of the Alps and Ligurian-Provence Basin. Journal Of Geophysical Research-Solid Earth, 128(10).
Résumé: Taking benefit of the AlpArray temporary network and permanent networks in W-Europe, we construct a 3-D onshore-offshore velocity model of the crust and upper mantle using ambient-noise wave-equation tomography. We use a frequency-dependent phase traveltime misfit function in an iterative procedure to refine a recent 3-D V-s model computed from a Bayesian two-step ambient noise tomography. Observed waveforms consist of vertical-component noise correlations from 600 broadband stations in the Alps and surroundings, including ocean-bottom seismometers in the Ligurian sea. We perform 3-D inversion in the 5-85 s period range. In the long-period band (20-85 s), an elastic approximation is considered, while in the 5-20 s band, we account for the effect of water layer in the Ligurian sea by applying a fluid-solid coupling for acoustic-elastic waveform simulations. The resulting V-s model enhances the shape and contrast of velocity structures, accounting for 3-D and finite-frequency effects. It emphasizes the deep sediments of the Ligurian-Provence basin and focuses on the low-velocity anomalies of the crust in the W-Alps. We obtain a high-resolution Moho depth map covering the Alps and Ligurian sea. In the W-Alps, this map confirms the deepening of the European crust following the subduction beneath Adria and the existence of major structures such as the Moho jump beneath the external crystalline massifs and shallow depths associated with the Ivrea Body. It provides further constraints on the deep structure beneath the Ligurian-Provence basin, regarding the lateral and along-strike crustal-thickness variations from the oceanic domain to the conjugate margins. In the complex tectonic setting of the Alps and Northwestern Mediterranean, a precise seismic mapping of the 3-D structure of Moho is crucial to understand the deep dynamic processes involved in the orogenesis of the western Alps and the opening of the Ligurian-Provence back-arc basin. Using an innovative wave-equation tomography of ambient noise recordings, we compute a high-resolution velocity model covering the Alps and Ligurian sea. In particular, we account for the influence of water and seabed relief on the 3-D propagation of surface waves in the Ligurian sea. We derive a high-resolution onshore-offshore 3-D map of Moho depth beneath the Alps and Ligurian-Provence basin. Our Moho map confirms the subduction of the European lithosphere beneath Adria. It shows strong depth variations in the Ligurian-Provence basin, from 12 km in the basin axis to similar to 20-25 km in the conjugate margins of Provence and Corsica.
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Nziengui-Ba, D., Coutant, O., Moreau, L., & Boue, P. (2023). Measuring the thickness and Young's modulus of the ice pack with DAS, a test case on a frozen mountain lake. Geophysical Journal International, 233(2), 1166–1177.
Résumé: We explored the potential of fibre optics coupled with distributed acoustic sensing (DAS) to measure the thickness and Young's modulus of an ice layer, using the properties of guided seismic waves. During two winter seasons (2020 and 2021), an optical fibre was deployed over one of the frozen Roberts Mountain lakes (at 2400 m a.s.l) near Grenoble (France) and we measured both the continuous ambient seismic noise as well as signals generated by active sources (hammer), with a DAS interrogator. Following a Bayesian scheme, we inverted the dispersion curves of longitudinal and flexural guided waves retrieved from the analysis of active shot gathers and obtained Young's modulus E = 3.4 +/- 0.1 GPa and ice thickness h = 47 +/- 1 cm from the second-year data. The ice thickness was consistent with field measurements. Field observations of porous and/or fracture ice may explain the relatively low effective Young's modulus (relative to pure ice), which may also be affected by a snow layer not included in the model. The drastic improvements in the inversion results between the two years are related to better coupling conditions (drone deployment before early freezing), more appropriate acquisition parameters (2 m gauge length), and the upper snow layers (less thick and less heterogeneous in the second year). Moreover, we were able to use the non-dispersive low-frequency noise associated with gravity waves to estimate the lake depth H = 5 m which is compatible with independent observations. The use of DAS to record guided seismic waves could then appear as a relevant tool for monitoring environments like floating ice shelves and sea ice.
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Ojeda, J., Morales-Yanez, C., Ducret, G., Ruiz, S., Grandin, R., Doin, M. - P., et al. (2023). Seismic and aseismic slip during the 2006 Copiapo swarm in North-Central Chile. Journal Of South American Earth Sciences, 123.
Résumé: Earthquake swarms commonly occur along the Chilean subduction zone, witnessing fast seismic and slow aseismic slip behavior at the plate interface. However, the largest seismic swarms observed in Chile, particularly in the Copiapo-Atacama region, remain poorly documented, and the underlying processes have yet to be understood. Here, we perform seismological and geodetic analyses to investigate the 2006 Copiapo swarm, which developed in April and May 2006. The swarm began on April 19, with a magnitude Ml 5.3 earthquake. During the nine following days, we observe a migration of seismicity along the plate interface, the occurrence of doublets events, and a potential slow slip event in the GPS time series at site Copiapo. Then, on April 30, a first earthquake with Mw 6.6 occurred at 15 km depth at the plate contact. It likely triggered a second earthquake of magnitude Mw 6.5, which occurred 144 min later, 10 km northwest of the first earthquake. Using InSAR, we determined the slip distribution associated with these two earthquakes and detailed the postseismic slip they triggered in the next days and weeks. This “postseismic”phase appears to be predominantly aseismic, while the moment released during the “coseismic”phase is comparable to other seismic crises that occurred in Atacama. Although we did not find a larger seismic and aseismic ratio than in other swarms in South America, we suggest a similar mechanism of slow deformation as a driver of seismicity during seismic swarms. Finally, we propose that the slow and fast behavior of the 2006 Copiapo swarm is a consequence of the subduction of the Copiapo Ridge seamounts, which affects both the plate interface and the overriding plate by inducing complex interactions between seismic and aseismic processes.
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Otero, J., Borsoi, G., & Monasterio-Guillot, L. (2023). The Boom in Nanomaterials for Built Heritage Conservation: Why Does Size Matter? Materials, 16(8).
Résumé: There is no doubt that nanotechnology and nanoscience open new doors to new applications and products that can potentially revolutionize the practice field and how we conserve built heritage materials. However, we are living at the beginning of this era and the potential benefits of nanotechnology to specific conservation practice needs are not always fully understood. This opinion/review paper aims to present reflections and answer a question that we are often asked when working directly with stone field conservators: why should we use a nanomaterial instead of a conventional product? Why does size matter? To answer this question, we revise the basic concepts of nanoscience with implications for the built heritage conservation field.
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Oursin, M., Pierret, M. - C., Beaulieu, E., Daval, D., & Legout, A. (2023). Is there still something to eat for trees in the soils of the Strengbach catchment? Forest Ecology And Management, 527.
Résumé: The global demand for wood is growing and the sustainability of forests has become an increasingly important issue. The first metre of soil represents the reserve of nutrients cations (K, Ca, Mg) for trees. The depletion of these elements in the soil gradually leads to a decrease in soil fertility, which can have a strong impact on the development and health of forests.The aim of this study was to better understand the source and dynamics of nutrients in forested soils from a base poor environment by combining mineralogic, chemical, isotopic and numerical tools through an experi-mental approach. We designed batch experiments to follow the leaching of soils from two experimental plots (under spruce and under beech from the Strengbach catchment, Vosges Mountain, NE France). The studied el-ements show highly contrasting behaviours. Mg release results from a mixing between cationic exchange, mineral dissolution (mainly smectite) and organic matter mineralization. The dynamics of K are underestimated by modelling, which may be attributed either to an unknown source of K or to an overestimation of the secondary phase precipitation. The Sr isotopic approach, used as a proxy to identify the sources of Ca, shows that the exchangeable complex supplies nutrients first and rapidly to the solution, followed by the clay compartment and at the very end, the bulk soils. Na is mainly controlled by albite dissolution.The release of Ca is significantly lower than that of other cations as Mg or K. Our results suggest that the exchangeable Ca, estimated through classical extractions, is only partly available for plants, due to strong chemical binding with organic matter and/or the occurrence of Ca-chemical bridges between clay and organic matter. Sustainable management should thus consider that exchangeable Ca, conventionally determined, does not necessarily provide an accurate picture of the real availability of Ca and therefore of the fertility of soils, with a risk of overestimation of nutrient reservoir for trees. Calcium tree nutrition at these sites has to rely on the long term on atmospheric deposition and an efficient recycling through biological cycling. This is also true for the other nutrient cations, but to a lesser extent since soil intrinsic fluxes (i.e., weathering, mineralisation of OM...) are not null and may thus supply the exchangeable pools and participate substantially to tree nutrition. Har-vesting and biomass exportation could rapidly impact the biological cycle and threaten the sustainability of these ecosystems, similar to changing tree species that may influence the nature of the litter, its turnover and the input of nutrients to the soil.
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Papaslioti, E. - M., Le Bouteiller, P., Carreira, H., Greneche, J. - M., Fernandez-Martinez, A., & Charlet, L. (2023). Immobilisation of contaminants by 'green'-synthesized magnetite as a remediation approach to the phosphogypsum waste leachates model solution. Journal Of Environmental Management, 341.
Résumé: Contaminant removal from (waste)waters by magnetite is a promising technology. In the present experimental study, a magnetite recycled from the steel industry waste (zero-valent iron powder) was used to investigate the sorption of As, Sb and U in phosphate-free and-rich suspensions, i.e. as a remediation for the acidic phospho-gypsum leachates derived from the phosphate fertilizer industry. The results showed up to 98% U removal under controlled pH conditions, while phosphate did not hinder this immobilisation. In contrast, the results confirmed the limited uptake of As and Sb oxyanions by magnetite in presence of phosphate as the competing anion, displaying only 7-11% removal, compared to 83-87% in the phosphate-free sorption experiments. To limit this wastewater problem, raw ZVI anaerobic oxidation was examined as mechanism to increase the pH and as a source of Fe2+ in a first step, and in a second step to remove phosphate via vivianite precipitation, therefore prior to the reaction with magnetite. UV-Vis, XRD and SEM-EDS showed that vivianite precipitation is feasible at pH > 4.5, mainly depending on the phosphate concentration. The higher the [PO43-], the lower is the pH at which vivianite precipitates and the higher the % removal of phosphate from solution. It is anticipated that an optimum 3-steps design with separate reactors controlling the conditions of ZVI oxidation, followed by vivianite precip-itation and finally, reaction with magnetite, can achieve high contaminant uptake in field applications.
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Pavlopoulos, K., Moraetis, D., Foumelis, M., Scharf, A., Mattern, F., Forman, S., et al. (2023). Uplift Dynamics of the Obducted Northeastern Continental Margin of the Arabian Peninsula, Sultanate of Oman. Geochemistry Geophysics Geosystems, 24(11).
Résumé: Eustatic sea level changes and vertical tectonic movements are producing uplifted paleoshorelines. Along subduction zones, uplifted terraces are used to study fault activities and, overall, allow to interpret the tectonic history of plate convergence. Northeastern Oman is experiencing plate convergence following the late Cretaceous obduction of the Semail Ophiolite. Post-obduction shallow-marine carbonates have been uplifted to different elevations from 133 to >2,000 m. The present study employs a multidisciplinary approach to elucidate the variability in relief and to introduce a geodynamic model that extends beyond the temporal constraints imposed by the late Quaternary age of the sediments found on the uplifted terraces. Stratigraphic and fault analyses produced a post-obductional geodynamic model to advance the existing regional models in the framework of the subduction of the Arabian Plate in the Makran Zone. In addition, we rely on imaging geodesy, geomorphology and dating to explain the late Quaternary uplift scenario. Overall, analyses of geomorphology, stratigraphy, and fault patterns reveal spatially heterogeneous post-late Cretaceous uplift in the region. Compartmentalization by major faults created individual blocks and relief variability. Within the timeframe of marine terrace formation (late Quaternary), we also observed spatially varied displacements. Ground displacements by Interferometric Synthetic Aperture Radar document an ongoing spatial heterogenous uplift at approximately 1.3 mm/a. Finally, temporal variability was evident during the late Quaternary by unusually high late Pleistocene (<40 ka) uplift rates averaging >= 2 mm/a in younger terraces, while for older terraces (>40 ka) the uplift rate is distinctly lower (<1 mm/a).
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Peccia, A., Moussallam, Y., Plank, T., DallaSanta, K., Polvani, L., Burgisser, A., et al. (2023). A New Multi-Method Assessment of Stratospheric Sulfur Load From the Okmok II Caldera-Forming Eruption of 43 BCE. Geophysical Research Letters, 50(21).
Résumé: The 43 BCE eruption of Okmok Volcano has been proposed to have had a significant climate cooling impact in the Northern Hemisphere. In this study, we quantify the climate cooling potential of the Okmok II eruption by measuring sulfur concentration in melt inclusions (up to 1,606 ppm) and matrix glasses and estimate a total of 62 +/- 16 Tg S released. The proportion reaching the stratosphere (2.5%-25%, i.e., 1.5-15.5 Tg S) was constrained by physical modeling of the caldera-collapse eruption. Using the NASA Goddard Institute for Space Studies E2.2 climate model we found a linear response between cooling and stratospheric sulfur load (0.05-0.08 degrees C/Tg S). Thus, the 1-2 degrees C of cooling derived from proxy records would require 16-32 Tg sulfur injection. This study underscores the importance of combining approaches to estimate stratospheric S load. For Okmok II, we find all methods are consistent with a range of 15-16 Tg S. Gaseous sulfur released in explosive volcanic eruptions can reflect incoming solar radiation in the stratosphere and cool the Earth's surface. Here, we calculate the total amount of sulfur released in the 43 BCE caldera-forming eruption of Okmok Volcano, Alaska by measuring the concentration of sulfur dissolved in magma prior to the eruption. We find that the total sulfur load from the Okmok II eruption is one of the largest in the last 2,500 years, and we use climate models to simulate cooling and precipitation anomalies associated with total or partial injection of volcanic sulfur into the stratosphere. However, the estimated sulfur load is larger than that predicted by sulfur signals preserved in ice cores, and physical modeling of the eruption suggests that only a proportion of the sulfur released reached stratospheric altitudes. Further, comparison of temperature reconstructions from tree ring and cave deposit proxies with climate model results show the cooling associated with the eruption requires only a fraction of the total sulfur load. Thus, we propose that only a quarter of the total sulfur released in the eruption made it to the stratosphere, responsible for 1-2 degrees C of cooling in the year following the eruption. Petrologic evidence suggests a total of 62 Tg S was released in the caldera-forming eruption of Okmok Volcano in 43 BCEClimate models respond linearly to stratospheric sulfur loads. 1-2 degrees C cooling from proxy records suggests 16-32 Tg S injectionA physical model constrains the proportion of stratospheric sulfur to 2.5%-25%; thus we find a common range for all methods of 15-16 Tg S
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Pedersen, H. A., Mattern, F., Poli, P., & Stehly, L. (2023). Imaging with seismic noise: improving extraction of body wave phases from the deep Earth through selective stacking based on H/V ratios. Geophysical Journal International, 232(2), 1455–1467.
Résumé: Generating high-resolution images of the deep Earth remains a challenge. Body waves extracted from noise correlations hold high promise to complement earthquake-based studies, but data processing and interpretation are still under development. We develop a methodology to improve signal-to-noise ratio (SNR) of P410P and P660P, waves reflected at the top and bottom of the mantle transition zone, using data from the greater Alpine area and focussing on the second microseismic peak (2.5-10 s period). Rather than stacking all available data, we only stack correlations for days with a low ratio of amplitudes between the horizontal plane and vertical direction (H/V). Due to an improved SNR we can stack over fewer correlation pairs, with the result that horizontal resolution is significantly improved. We propose a systematic approach to determine at each study point the optimal combination of station pairs and the H/V threshold. We observe that the optimal choice of parameters is location dependent and that it is generally different for P410P and P660P. Additionally, we show that in our study area the maximum interstation distance needs to be reduced to similar to 150 km for P410P to avoid that this arrival is contaminated by surface waves. Applied to the greater Alpine area we demonstrate a significant improvement of signal extraction: while P410P and P660P were only sporadically identified in standard stacks, with the new processing scheme these arrivals are clearly identified with coherent phases across large distances. We also show that amplitudes of P660P decrease drastically around longitude similar to 11 degrees E to similar to 12 degrees E, indicating that the lower discontinuity of the transition zone in that area is too broad to have a significant reflexion coefficient for P waves in the second microseismic peak.
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Pedoja, K., Dunan-Avila, P., Jara-Munoz, J., Authemayou, C., Nunez-Labanino, A., de Gelder, G., et al. (2023). On a ∼210 t Caribbean coastal boulder: The <i>huracanolito</i> seaward of the ruins of the Bucanero resort, Juragua, Oriente, Cuba. Earth Surface Processes And Landforms, 48(15), 3074–3090.
Résumé: Coastal boulder deposits (CBDs), named huracanolitos in Cuba, found along rocky shores, result from storms, tropical cyclones or tsunamis. Despite being important indicators for coastal hazard assessment, determining the mode of emplacement of CBDs (storm/hurricane or tsunami) is not easy. We present, for the first time in English, data about CBDs along the shores of the Cuban Archipelago. More specifically, we focused on a CBD, that is, to our knowledge, the largest one ever described on Cuba Island. Located on a low-lying coral reef terrace on the SE shore of the island, the reefal limestone CBD is emplaced seaward of the ruins of the Bucanero resort. The resort was built in 1989, endured hurricanes Ivan (2004) and Dennis (2005) and, in October 2012, was destroyed by Hurricane Sandy. As observed on Corona and Landsat satellite images since 1962, the CBD was not moved, neither by hurricane Flora (1963) nor Sandy (2012), both associated with important storm surges and powerful swells. We determined the CBD volume with open-source structure from motion photogrammetry as 82.6 m(3). Then, we estimated from a sample its density as 2550 kg/m(3). Finally we calculated its weight as 210.6 tons. We calculated the minimum flow velocity responsible for the emplacement of the CBD 33 +/- 2 m inland-6.83 +/- 0.54 m/s and 7.26 +/- 0.51 m/s. Such flow velocities are compatible with those of both tsunamis and hurricanes. Because of the greater frequency of hurricanes than tsunamis in the area, we propose that a tropical cyclone generated the extreme surge and wave that emplaced the Bucanero CBD. Such CBDs demonstrate that on Cuba's south coast, we can expect marine flooding exceeding the flooding during the major hurricanes of recent decades.
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Peng, W., Radiguet, M., Pathier, E., & Chen, K. H. (2023). Fault Coupling on a Creeping Thrust Fault: Joint Inversion Using Geodetic Data and Repeating Earthquakes. Journal Of Geophysical Research-Solid Earth, 128(9).
Résumé: Due to the lack of recognized creep on dip-slip faults, the nature of fault creep and its role in the generation of large earthquakes is largely unexplored. The Chihshang fault in Taiwan serves as one of the best examples of a thrust creeping fault in the world, exhibiting a fast creep rate of 2-3 cm/year and the capability of producing magnitude six earthquakes. Land-based geodetic measurements are less sensitive to fault slip with depth, especially for the deeper portion of the seaward dipping fault. Taking advantage of slip rates inferred from repeating earthquake sequences (RESs) at greater depths (up to 30 km), we present a method that embeds RES-derived slip rates into the neighboring fault patch for geodetic data inversion. Using the geodetic and seismological data from 2007 to 2011, we achieve a higher resolution of inter-seismic slip rate distribution below a depth of 10 km. The inferred low coupling ratio establishes an extensive creeping area that coincides with a location of abundant RES and earthquake swarms. The inferred high coupling ratio, on the other hand, delineates a locked area corresponding to the two co-seismic slip zones of the 2003 M-w 6.8 Chengkung and 2022 Mw 6.7 Yuli earthquakes. The transition zone marking the gradual change from fully locked to shallow creeping areas appears to coincide with the post-seismic slip area of the 2003 Chengkung event. Using the fault coupling model, the moment rate deficit measured in the two locked areas is capable of generating a Mw 6.8 event every 78 years to the south and a M-w 6.7 event every 28 years to the north. This moment rate deficit is decreased by 10% when the closely located Central Range fault is considered in a two-fault model, leading to the slightly longer recurrence interval on the Chihshang fault. The two-fault model potentially contributes to a better understanding of the regional inter-seismic deformation, which is recommended to be adopted in the future studies of seismic hazard assessment.
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Perfettini, H., & Molinari, A. (2023). The Interaction Between Frictional Slip and Viscous Fault Root Produces Slow Slip Events. Journal Of Geophysical Research-Solid Earth, 128(3).
Résumé: We consider a model where an unstable frictional region, governed by rate and state friction, interacts with a viscous zone with Newtonian rheology. The system is loaded at distance with a constant velocity. Pore pressure variations are considered and we show that the model of Segall and Rice (1995, ) relating porosity changes to variations of the state variable could be derived considering viscoplastic deformation of a population of identical asperities. We perform a linear stability analysis in the case of a constant pore pressure in agreement with the full numerical results. For a given value of the viscosity of the viscous region, stable slip is promoted at low normal stress and unstable slip at high normal stress. Near the transition from stable to unstable slip, modest acceleration of slip, resembling slow slip events (SSE) are observed. We show that our model can reproduce real SSE sequences in the Guerrero subduction zone which are the largest worldwide. The best fit parameters suggest that SSEs happen in areas of low effective normal stress (for the frictional region) and low viscosity (for the viscous region). In our model, SSEs happen in a regime where the viscous region is able to counteract the instability of the frictional one. We show that considering a rate strengthening rheology or a non newtonian one leads to the same linear stability results. Our work shows that a simple model with homogeneous spatial properties can lead to complex dynamics, covering a wide range of observed sliding modes, from steady-state creep to seismic slip and SSEs.
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Peters, V. F. D., Baken, A., Seepma, S. Y. M. H., Koskamp, J. A., Fernandez-Martinez, A., van Driessche, A. E. S., et al. (2023). Effect of Solution Stoichiometry on BaSO<sub>4</sub> Crystallization from Turbidity Measurements and Modeling. Industrial & Engineering Chemistry Research, 63(1), 78–88.
Résumé: The impact of solution stoichiometry on the nucleation and growth of BaSO4 was studied by measuring solution transmittance and subsequent fitting to a crystallization model. Our results show that a large excess of either Ba2+ or SO42- ions inhibits both the nucleation and growth of BaSO4. However, for a small excess of Ba2+, the growth is enhanced. The dependence of nucleation and growth rates on supersaturation and solution stoichiometry was captured by a semiempirical rate model. Hence, the solution stoichiometry is a highly relevant parameter while studying all aspects of BaSO4 crystallization, and it could be worthwhile to examine other minerals similarly.
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Petit, C., Salles, T., Godard, V., Rolland, Y., & Audin, L. (2023). River incision, <SUP>10</SUP>Be production and transport in a source-to-sink sediment system (Var catchment, SW Alps). Earth Surface Dynamics, 11(2), 183–201.
Résumé: Detrital Be-10 from continental river sands or submarine sediments has been extensively used to determine the average long-term denudation rates of terrestrial catchments, based on the assumption that the rate of cosmogenic nuclide production by the interaction of source rocks with cosmic radiation balances out the loss of these nuclides by surface denudation. However, the Be-10 signal recorded in sediments may be affected at the source by the response time of mountainous catchments to high-frequency forcings. In addition, transient sediment storage in piedmonts, alluvial plains and lakes or near the coast may also induce a difference between the erosive signal and its record in the sedimentary sink. Consequently, a significant part of the signal recorded in shallow-water sediments can be lost, as deep marine sediments may simultaneously record a signal coming from newly eroded source rocks along with one coming from the destabilization of previously deposited sediments. In this paper, we use the landscape evolution model Badlands to simulate erosion, deposition and detrital Be-10 transfer from a source-to-sink sedimentary system (the Var River catchment, southern French Alps) over the last 100 kyr. We first compare model-based denudation rates with the ones that would be extracted from the Be-10 record of local continental sediments (equivalent to river sands) and from sediments deposited offshore over time in order to examine if this record provides an accurate estimate of continental denudation rates. Then, we examine which conditions (precipitation rate, flexure, ice cover) satisfy published measured river incision rates and Be-10 concentration in submarine sediments. Our results, based on the Var catchment cosmic ray exposure dating and modelling indicate that, while river sands do accurately estimate the average denudation rate of continental catchments, this is much less the case for deep submarine sediments. We find that deep-sea sediments have a different and often much smoother Be-10 signature than continental ones and record a significant time lag with respect to imposed precipitation rate changes, representing the geomorphological response of the margin. A model which allows us to fit both measured Be-10 concentration in marine sediments and river incision rates on land involves an increase in precipitation rates from 0.3 to 0.7myr(-1) after 20 ka, suggesting more intense precipitation starting at the end of the Last Glacial Maximum.
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Pimentel, C., Zheng, M., Cartwright, J. H. E., & Sainz-Diaz, C. I. (2023). Chemobrionics Database: Categorisation of Chemical Gardens According to the Nature of the Anion, Cation and Experimental Procedure. Chemsystemschem, 5(4).
Résumé: Considering the growing importance of the field of chemobrionics since the term was coined in 2015 and the increase in the number of published papers, it has become necessary to catalogue all the papers published to date. Here, we present the chemobrionics database, which lists all the chemical gardens synthesised according to their anion, cation and experimental protocol. The aim of this database is to encourage the study and dissemination of chemical gardens in order to find new experimental avenues in the field of chemobrionics. As this is such a fruitful field, the database is continuously updated.
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Pinto, V. H. G., Manatschal, G., Karpoff, A. M., Masini, E., Victor, R. A., Viana, A. R., et al. (2023). Mass-Transfer and Fluid Flow along Extensional Detachment Faults in Hyperextended Rift Systems: The Examples of Tasna in the Alps, Mauléon in the Pyrenees, and Hobby High Offshore Iberia. Geosciences, 13(12).
Résumé: Hyperextended rift systems are characterized by extreme crustal thinning and mantle exhumation associated with extensional detachment faults. These faults cut through thinned continental crust, reaching the underlying mantle and allowing for seawater to infiltrate and react with the crustal and mantle rocks. Hydrothermal fluid systems linked to detachment faults result in fluid-rock reactions occurring along the detachments, resulting in the breakdown and alteration of minerals, loss of elements and strain weakening in both mantle and crustal rocks. We present new geological observations and geochemical data from the modern Iberia and fossil Alpine Tethys Ocean Continent Transition and the West Pyrenean Mauleon hyperextended rift basin. We show evidence for a km-scale fluid flow along detachment faults and discuss the conditions under which fluid flow and mass transfer occurred. Convective fluid systems are of major importance for mass transfer between the mantle, crustal and marine reservoirs. We identified gains in Si, Mg, Fe, Mn, Ca, Ni, Cr and V along extensional detachment faults that we relate to channelized, hydrothermal crust- and mantle-reacted fluid systems migrating along detachments in the hyperextended continental crust. The observation that fault rocks of extensional detachment and syn-extensional sedimentary rocks are enriched in mantle-derived elements such as Cr, Ni and V enables us to define the pathways of fluids, as well as to estimate their age relative to detachment faulting and sedimentation. Because all three examples show a similar mass transport of elements along detachment systems at km-scale, we conclude that these examples are linked to convective fluid systems that may affect the thermal state of the lithosphere, as well as the rheology and chemistry of rocks in hyperextended systems, and may have implications for ore mineral exploration in hyperextended rift systems.
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Plunian, F., & Alboussiere, T. (2023). Dynamo action produced by an anisotropic rotor immersed in an electrically conducting medium at rest. Physical Review Fluids, 8(11).
Résumé: It is shown that the rotational motion of a cylindrical rotor immersed in an electroconducting medium at rest can produce a dynamo effect, provided that the electrical conductivity or magnetic permeability of the rotor is anisotropic. Results are reported for three pairs of rotor materials: copper/kapton, iron/tin, and mu-metal/tin. The value of using such an anisotropic rotor in liquid metal such as sodium or galinstan for a laboratory dynamo experiment is clearly demonstrated.
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Poudel, A., Pitilakis, K., Silva, V., & Rao, A. (2023). Infrastructure seismic risk assessment: an overview and integration to contemporary open tool towards global usage. Bulletin Of Earthquake Engineering, 21(9), 4237–4262.
Résumé: Infrastructures are critical for the functioning of society. Due to globalization, damages between different components of infrastructure systems can cross international boundaries, resulting in broad economic and social impacts. Hence, it is fundamental to develop powerful tools for the assessment of infrastructure risk, considering a wide spectrum of uncertainties. Past studies covering infrastructure risk assessment are limited to a few countries, partly because for assessing the infrastructure risk, issues due to the complexity of the systems, like paucity and heterogeneity of the data and methods, the consideration of dependencies between components and systems, modeling of ground shaking in terms of scenario and probabilistic approach, taking into account site effects, spatial variability and cross correlation of ground motion at the urban scale, as well as consideration of risk metrics tailored to infrastructure, still remain partially or not properly answered. Moreover, the presently available infrastructure risk assessment tools are not sufficiently illustrative, user-friendly, and comprehensive to meet actual needs. To this end, the paper making an overview of these issues proposes a comprehensive approach that leverages the main strength of existing infrastructure risk methodologies, integrating them into a powerful open-source tool and providing common platform from hazard to risk analysis that will serve for global and easy usage. The methodology and its implementation are illustrated through a test-bed study of the water supply network of the city of Thessaloniki in Greece, considering an M-w 6.5 scenario of the 1978 Thessaloniki earthquake and an event based probabilistic approach and, simultaneously evaluating the sensitivity of cross spatial correlation.
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Provenzano, G., Brossier, R., & Metivier, L. (2023). Robust and efficient waveform-based velocity-model building by optimal transport in the pseudotime domain: Methodology. Geophysics, 88(2), U49–U70.
Résumé: Full-waveform inversion (FWI) aims at a broadband reconstruction of the subsurface physical properties by fitting the entire recorded wavefield. In realistic exploration seismic sur-veys, however, conventional FWI often fails to retrieve the deep velocity model due to the limited penetration depth of diving waves. Joint FWI (JFWI) unifies reflection-waveform inversion and early arrival waveform inversion to reconstruct simultane-ously the shallow and deep subsurface kinematics. However, sev-eral factors limit the appeal of JFWI velocity-model building: (1) conflict between fixed reflectivity and evolving kinematics, creating phase ambiguity at short offsets; (2) susceptibility to cycle skipping at mid-to-long offsets, thus reliance on the quality of the starting model; and (3) cost of building and updating the reflective model. We have developed a fully operational JFWI-based methodology that systematically addresses the aforemen-tioned issues. JFWI is reformulated in the pseudotime domain, to enforce consistency between velocity and reflectivity in a cost-effective fashion, without repeated least-squares migrations. A JFWI graph-space optimal transport (GSOT) objective function is designed to avert cycle skipping, whereas nonuniqueness is mi-tigated at no extra cost by smoothing the velocity gradient along the structures extracted from the reflective model. A dedicated asymptotic-based preconditioner is developed for impedance waveform inversion, making it possible to obtain sharp and bal-anced reflective images in a fraction of the time. We determine that pseudotime GSOT-JFWI retrieves complex velocity macro -models from limited-offset data sets with minimal preprocessing, starting from noninformative initial solutions. Compared with depth-domain JFWI, the computing cost is reduced significantly, along with a simpler and less subjective design of data weighting and inversion strategy. Pseudotime GSOT-JFWI provides FWI with the necessary low wavenumbers to converge to the broad-band model, reducing the need for accurate starting models, on the road to a fully waveform-based imaging workflow.
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Rashidi, A., Dutykh, D., & Beck, C. (2023). Modeling the potential genesis of tsunamis from below an accretionary prism and their potential impact: a case study along the eastern boundary of the Caribbean Plate. Natural Hazards, 118(1), 307–329.
Résumé: The Lesser Antilles subduction zone marks the convergence between the Caribbean Plate and the oceanic Atlantic part of the America Plate. A specificity of this subduction is the development of a huge accretionary prism, the Barbados complex. As other subduction zones, the Lesser Antilles one has the potential to produce megathrust-associated earthquakes and related tsunamis. This study evaluates the potential hazard of tsunami scenarios along this eastern boundary of the Caribbean Plate, taking into account its specificities. We define six scenarios along the Lesser Antilles subduction zone including three M-w 7.5, 8.0 and 8.5 earthquake models, in both northern and southern parts of the arc. We incorporate in tsunami simulations the effect of sediment amplification in tsunami generation. In the southern half, the thick sediments pile, related to tectonic accretion, appears much more effective than the much thinner accumulation characterizing the northern half. The bed shear stress is also computed in this study as it is an important factor in sediment transport which can show the potential locations for sediment movement by tsunamis. Our results indicate the ability of scenario earthquakes to produce powerful tsunamis. The impacts of northern scenarios on Guadeloupe could be severe (maximum tsunami wave height of > 5 m ), whereas the impacts from southern scenarios are relatively less strong (maximum wave amplitude of < 5 m ). The tsunami waves produced by M-w 8.0 and 8.5 appear able to inundate the coast of Sainte-Anne, Guadeloupe, up to 2 km . The distributions of bed shear stress from northern scenarios suggest that the offshore Leeward Islands could be potentially prone to sediment transport as possible tsunami deposits have been found in the region in former geological studies.
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Rashidi, A., Dutykh, D., & Beck, C. (2023). Modeling the potential genesis of tsunamis from below an accretionary prism and their potential impact: a case study along the eastern boundary of the Caribbean Plate (vol 118, pg 307, 2023). Natural Hazards, .
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Ravanel, L., Mourey, J., Tamian, L., Ibanez, S., Hantz, D., Lacroix, P., et al. (2023). Climbing Mont Blanc (4808 m a.s.l.): What Are the Risks in the Grand Couloir Du Goûter and On the North Face of Mont Blanc Du Tacul? Revue De Geographie Alpine-Journal Of Alpine Research, 111(2).
Résumé: Mountaineering is a sport highly dependent on the conditions of the physical environments in which it takes place. As a result, mountaineers have to deal with major glacial and periglacial hazards, such as those affecting the two main routes used to climb Mont Blanc (4808 m a.s.l.; Western European Alps): rockfalls in the Grand Couloir du Gouter on the Voie Royale and serac falls on the NNW slope of Mont Blanc du Tacul on the Trois Monts route. Hazards in these two sectors and the number of climbers were measured using a multi-sensor system and automatic photographic acquisition, respectively. On the first site, which has a very high accident rate with an average of 3.7 deaths per year, 17,768 passages were recorded during the summer of 2019 and 2,648 seismic signals were classified as rockfalls affecting the Grand Couloir. The average risk of death associated with these rockfalls, the frequency of which depends on temperatures and the presence of liquid water in the ground, is estimated at 1.7 x 10-4. At Tacul, where an average of 0.6 deaths occur each year, 6,770 passages were recorded during the summer of 2017, as well as 31 serac falls unrelated to temperatures. The risk of death is 8.3 x 10-5. The risk is also quantified for each track made on the glacier. The results obtained makes it possible to specify the risks experienced by climbers and to promote risk reduction strategies.
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Reigl, S., Van Driessche, A. E. S., Wagner, E., Montes-Hernandez, G., Mehringer, J., Koltzenburg, S., et al. (2023). Toward More Sustainable Hydraulic Binders: Controlling Calcium Sulfate Phase Selection via Specific Additives. Acs Sustainable Chemistry & Engineering, 11(23), 8450–8461.
Résumé: This work shows how additive-controlledcrystallizationmay be leveraged as an alternative route toward more sustainable productionof hydraulic binders. Bassanite (calcium sulfate hemihydrate) is one of themost extensivelyused inorganic binders in construction applications. Current industrialprocesses for the large-scale production of the mineral rely almostexclusively on the thermal dehydration of gypsum (calcium sulfatedihydrate), which consumes considerable amounts of energy. Here, weshow that phase-pure bassanite can be obtained in high quantitiesby spontaneous precipitation from supersaturated solutions at moderatetemperatures, where gypsum usually forms as a predominant solid phase.Key to control over phase selection is the presence of specific additivesduring crystallization, which carry functional groups for bindingonto calcium sulfate surfaces as well as additional moieties thatwithdraw water in the local microenvironment. Some of the investigatedadditives allowed bassanite to be recovered in large amounts at temperaturesas low as 40 degrees C and added concentrations of only 0.1 M or evenless. The concepts described in this work pave the way toward alternativeapproaches, enabling a less energy-intensive and thus more sustainableproduction of bassanite for use in construction and other appliedsystems.
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Repasch, M., Scheingross, J. S., Cook, K. L., Sachse, D., Dosch, S., Orfeo, O., et al. (2023). Lithospheric Flexure Controls on Geomorphology, Hydrology, and River Chemistry in the Andean Foreland Basin. Agu Advances, 4(5).
Résumé: Tectonics exerts a strong control over the morphology of Earth's surface that is apparent in active mountain belts. In lowland areas, subtle processes like lithospheric flexure and isostatic rebound can impact Earth surface dynamics, hydrologic connectivity, and topography, suggesting that geomorphic and hydrologic analyses can shed light on underlying lithospheric properties. Here we examine the effect of lithospheric flexure on the geomorphology, hydrology, and river water chemistry of the Rio Bermejo fluvial system in the east Andean foreland basin of northern Argentina. Results show that proximal to the mountain front, foredeep basin subsidence causes sedimentation along a braided channel belt that is superelevated relative to the surrounding flood basin. During floods, water flows from the superelevated channel into the groundwater reservoir, causing a net loss of discharge with distance downstream. Further downstream, forebulge uplift forces channel narrowing, high lateral migration rates, and incision up to 13 m into older river deposits. This incision locally allows groundwater flow into the river, causing a similar to 20% increase in river solute load. Groundwater emerges from the forebulge into the backbulge, predominantly as spring-fed channels. Here, channel migration rates decrease, suggesting a switch from net uplift to subsidence that reduces the depth to the groundwater table. This analysis shows that subtle lithospheric flexure can have significant effects on river channel morphology that determine hydrologic flow paths, and ultimately influence geochemical and ecological patterns. We suggest that these effects may elucidate lithospheric properties that are otherwise inferred from bulk geophysical observations.
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Rezaeifar, M., Lavoue, F., Maggio, G., Xu, Y., Bean, C. J., Pinzon-Rincon, L., et al. (2023). Imaging shallow structures using interferometry of seismic body waves generated by train traffic. Geophysical Journal International, 233(2), 964–977.
Résumé: Train-induced vibrations act as potential powerful high-frequency source for imaging subsurface with higher resolution than typical ambient noise interferometry. In this study, we present results of seismic interferometry applied on three days of railroad traffic data recorded by an array of seismographs along a railway in Dublin, Ireland. Our virtual shot gathers show significant surface and body wave energy that could be used for seismic interferometry. Reflection sections obtained with our interferometry approaches applied on selected time windows of train-induced vibrations is consistent with nearby borehole data and an active seismic profile. The consistency of the results given by these approaches confirms that train-generated vibrations represent a valuable source of signal for high-resolution subsurface imaging. Furthermore, our results show spurious arrivals that are due to the train geometry and also the cross-correlation approach that needs consideration for body wave interferometry studies.
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Richter, T., Dansereau, V., Lessig, C., & Minakowski, P. (2023). A dynamical core based on a discontinuous Galerkin method for higher-order finite-element sea ice modeling. Geoscientific Model Development, 16(13), 3907–3926.
Résumé: The ability of numerical sea ice models to reproduce localized deformation features associated with fracture processes is key for an accurate representation of the ice dynamics and of dynamically coupled physical processes in the Arctic and Antarctic.Equally key is the capacity of these models to minimize the numerical diffusion stemming from the advection of these features to ensure that the associated strong gradients persist in time, without the need to unphysically re-inject energy for re-localization.To control diffusion and improve the approximation quality,we present a new numerical core for the dynamics of sea ice that is based on higher-order finite-element discretizations for the momentum equation and higher-order discontinuous Galerkin methods for the advection. The mathematical properties of this core are discussed, and a detailed description of an efficient shared-memory parallel implementation is given. In addition, we present different numerical tests and apply the new framework to a benchmark problem to quantify the advantages of the higher-order discretization. These tests are based on Hibler's viscous-plastic sea ice model, but the implementation of the developed framework in the context of other physical models reproducing a strong localization of the deformation is possible.
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Roattino, T., Crouzet, C., Vassallo, R., Buoncristiani, J. - F., Carcaillet, J., Gribenski, N., et al. (2023). Paleogeographical reconstruction of the western French Alps foreland during the last glacial maximum using cosmogenic exposure dating. Quaternary Research, 111, 68–83.
Résumé: The extent of glaciers in the western French Alps foreland during the last glacial maximum (LGM, 26.5-19 ka) has not yet been determined, so understanding glacial paleogeography during the LGM remains an open question. This study focuses on the glacial chronology in the western French Alps piedmont using Be-10 surface exposure ages on nine glacial boulders and 12 erratic boulders. Results indicate an LGM glacier advance between ca. 24 and 21 ka. During the late LGM, a smaller glacier readvance or stabilization phase occurred at ca. 19 ka, which was followed by a withdrawal phase between ca. 19 and 16.5 ka. Our outcomes show that the LGM extent in the western French Alps was similar or slightly less extensive than the pre-LGM ice extents during the last glacial. Such paleogeography has also been suggested in the western Italian Alps, which share the same accumulation zone with the western French Alps glaciers. The LGM dynamic of the western French Alps foreland glaciers highlighted by our exposure ages is consistent with the timing of the LGM glacier advances and deglaciation with the western Italian ice lobes.
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Robles, M., Peyron, O., Menot, G., Brugiapaglia, E., Wulf, S., Appelt, O., et al. (2023). Climate changes during the Late Glacial in southern Europe: new insights based on pollen and brGDGTs of Lake Matese in Italy. Climate Of The Past, 19(2), 493–515.
Résumé: The Late Glacial (14 700-11 700 cal BP) is a key climate period marked by rapid but contrasted changes in the Northern Hemisphere. Indeed, regional climate differences have been evidenced during the Late Glacial in Europe and the northern Mediterranean. However, past climate patterns are still debated since temperature and precipitation changes are poorly investigated towards the lower European latitudes. Lake Matese in southern Italy is a key site in the central Mediterranean to investigate climate patterns during the Late Glacial. This study aims to reconstruct climate changes and their impacts at Matese using a multi-proxy approach including magnetic susceptibility, geochemistry (XRF core scanning), pollen data and molecular biomarkers like branched glycerol dialkyl glycerol tetraethers (brGDGTs). Paleotemperatures and paleo-precipitation patterns are quantitatively inferred from pollen assemblages (multi-method approach: modern analogue technique, weighted averaging partial least-squares regression, random forest and boosted regression trees) and brGDGT calibrations. The results are compared to a latitudinal selection of regional climate reconstructions in Italy to better understand climate processes in Europe and in the circum-Mediterranean region. A warm Bolling-Allerod and a marked cold Younger Dryas are revealed in all climate reconstructions inferred from various proxies (chironomids, ostracods, speleothems, pollen, brGDGTs), showing no latitudinal differences in terms of temperatures across Italy. During the Bolling-Allerod, no significant changes in terms of precipitation are recorded; however, a contrasted pattern is visible during the Younger Dryas. Slightly wetter conditions are recorded south of 42(?) N, whereas dry conditions are recorded north of 42(?) N. During the Younger Dryas, cold conditions can be attributed to the southward position of North Atlantic sea ice and of the polar frontal jet stream, whereas the increase in precipitation in southern Italy seems to be linked to relocation of Atlantic storm tracks into the Mediterranean, induced by the Fennoscandian ice sheet and the North European Plain. By contrast, warm conditions during the Bolling-Allerod can be linked to the northward position of North Atlantic sea ice and of the polar frontal jet stream.
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Roger, M., de Leeuw, A., van der Beek, P., Husson, L., Sobel, E. R., Glodny, J., et al. (2023). Construction of the Ukrainian Carpathian wedge from low-temperature thermochronology and tectono-stratigraphic analysis. Solid Earth, 14(2), 153–179.
Résumé: The evolution of orogenic wedges can be determined through stratigraphic and thermochronological analysis. We used apatite fission-track (AFT) and apatite and zircon (U-Th-Sm) / He (AHe and ZHe) low-temperature thermochronology to assess the thermal evolution of the Ukrainian Carpathians, a prime example of an orogenic wedge forming in a retreating subduction zone setting. Whereas most of our AHe ages are reset by burial heating, 8 out of 10 of our AFT ages are partially reset, and none of the ZHe ages are reset. We inverse-modeled our thermochronology data to determine the time-temperature paths of six of the eight nappes composing the wedge. The models were integrated with burial diagrams derived from the stratigraphy of the individual nappes, which allowed us to distinguish sedimentary from tectonic burial. This analysis reveals that accretion of successive nappes and their subsequent exhumation mostly occurred sequentially, with an apparent increase in exhumation rate towards the external nappes. Following a phase of tectonic burial, the nappes were generally exhumed when a new nappe was accreted, whereas, in one case, duplexing resulted in prolonged burial. An early orogenic wedge formed with the accretion of the innermost nappe at 34 Ma, leading to an increase in sediment supply to the remnant basin. Most of the other nappes were accreted between 28 and 18 Ma. Modeled exhumation of the outermost nappe started at 12 Ma and was accompanied by out-of-sequence thrusting. The latter was linked to emplacement of the wedge onto the European platform and consequent slab detachment. The distribution of thermochronological ages across the wedge, showing non-reset ages in both the inner and outer part of the belt, suggests that the wedge was unable to reach dynamic equilibrium for a period long enough to fully reset all thermochronometers. Non-reset ZHe ages indicate that sediments in the inner part of the Carpathian embayment were mostly supplied by the Inner Carpathians, while sediments in the outer part of the basin were derived mostly from the Teisseyre-Tornquist Zone (TTZ) or the southwestern margin of the East European Platform. Our results suggest that during the accretionary phase, few sediments were recycled from the wedge to the foredeep. Most of the sediments derived from the Ukrainian Carpathian wedge were likely transported directly to the present pro- and retro-foreland basins.
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Rosat, S., & Gillet, N. (2023). Intradecadal variations in length of day: Coherence with models of the Earth's core dynamics. Physics Of The Earth And Planetary Interiors, 341.
Résumé: We confirm the presence of interannual oscillations of period about 5.9 and 8.5 years in the Earth's length of day (LOD), better visible after subtracting the atmospheric contribution. Continental water mass redistribution and oceanic angular momentum contribute to a lesser extent, and are furthermore mostly compensated by sea level variations. We show, using a continuous wavelet transform analysis of synthetic oscillators embedded into a random correlated noise, the limits of isolating damped signals presenting nearby periods in time series of limited duration. In particular, we emphasize the possibility that a previously documented 7.3-year oscillation could be an artefact associated with the restricted available time span covered by LOD data. Finally, we perform a wavelet coherence analysis between geodetically observed LOD changes and their prediction from geomagnetically inferred core flow models. It confirms an origin from the fluid outer core for the two signals around 5.9 and 8.5 years. A convincing coherence is also found around 3.5 and 5 years, which may reveal signatures of higher harmonics of torsional modes or of quasi-geostrophic magneto-Coriolis modes.
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Rousset, B., Campillo, M., Shapiro, N. M., Walpersdorf, A., Titkov, N., & Chebrov, D. V. (2023). The 2013 Slab-Wide Kamchatka Earthquake Sequence. Geophysical Research Letters, 50(4).
Résumé: Studies of initiation of large earthquakes are usually focused on frictional instabilities occurring in the near vicinity of the future rupture. Possible contributions of long-distance interactions with large-scale tectonic instabilities remain unknown. Here we analyze seismic catalogs and geodetic time series during a few months preceding the 2013 M = 8.3 deep-focus Okhotsk earthquake. This deep-focus event is preceded by four intense seismic clusters in the seismogenic zone. GNSS time series in Kamchatka revealed a transient landward motion episode 1 month prior to the mainshock, consistent with an increase of seismogenic zone loading. This transient loading episode is accompanied by a doubling of the intermediate depth seismicity rate suggesting a transient slab pull as the origin. These observations question the constant subducting velocity hypotheses and may have implications in the understanding of the long-distance along-slab stress interactions and in their contribution to initiation of large deep-focus earthquakes.
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Roy, S., Vassallo, R., Martinod, J., & Sue, C. (2023). Ten Thousand Years of Paleo-Earthquakes Record of the Magallanes-Fagnano Plate Boundary Fault in Tierra del Fuego, Argentina. Tectonics, 42(4).
Résumé: The Magallanes-Fagnano Fault is an active left-lateral strike-slip fault that cuts across Tierra del Fuego, forming the boundary between the South American and the Scotia plates. This fault may trigger strong earthquakes, as documented by the occurrence of two M-w >= 7.5 in December 1949. However, this region is characterized by one of the shortest historical archives in the world and by a growing population. The geological record is therefore needed in order to characterize the seismic information over a longer time scale and to improve the seismic hazard assessment. We conducted extensive field work, neotectonic mapping and excavated two paleoseismic trenches across one of the sharpest tectonic scarps in the Eastern onshore portion of the fault. Using scarp-derived colluvial wedges, cross-cutting relations, and 28 radiocarbon samples, we document evidences of at least six paleo-earthquakes during the Holocene. Paleoseismic record is particularly accurate for the last two thousand years, for which period we determine an average recurrence interval of 1080 +/- 150 years. For repeated earthquakes of same magnitude as the 1949 event, this recurrence interval is compatible both with the known geodetic and geomorphic slip rates. However, “paired earthquakes” in less than one or two centuries may also occur, suggesting that fault behavior could be characterized by irregular seismic cycles. Plain Language Summary The Magallanes-Fagnano Fault is a main active fault in Tierra del Fuego, at the southern tip of South America. This remote region has one of the shortest historical seismic record in the world. However, this fault may trigger strong earthquakes as occurred in 1949 and the surrounding population has been massively growing since. We therefore studied the paleo-earthquake history of the fault to improve the seismic hazard assessment. We analyzed and dated the disrupted sediments in two trenches excavated across the fault to establish a paleo-earthquake calendar. We document evidences of at least six paleo-earthquakes during the last ten thousand years. Paleoseismic record is particularly accurate for the last two thousand years, for which period we determine a recurrence interval of 1080 +/- 150 years. However, “paired” major earthquakes in less than one or two centuries may also occur, suggesting that fault behavior could not be based on regular seismic cycles.
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Sakai, F., Hirose, K., & Morard, G. (2023). Partitioning of silicon and sulfur between solid and liquid iron under core pressures: Constraints on Earth's core composition. Earth And Planetary Science Letters, 624.
Résumé: Not only the Earth's outer core but also the inner core contains light elements, which causes reductions in density and velocity with respect to those of pure solid iron. Silicon, sulfur, and possibly hydrogen are believed to be important inner core light elements, because their partition coefficients between solid Fe and liquid, D (solid/liquid), are high (>0.7) under inner core pressures unlike other possible light elements such as oxygen and carbon. Recent experiments demonstrated that D-Si is remarkably enhanced with increasing sulfur concentration in liquid at 15-21 GPa. Here we conducted solid/liquid partitioning experiments on the Fe-Si-S(-C) system up to the Earth's core pressure range of 189 GPa in a laser-heated diamond-anvil cell (DAC) and examined the effect of silicon-sulfur interaction on both D-Si and D-S. The results show that D-S significantly diminishes with increasing the silicon content in liquid, while D-Si increases with higher sulfur concentration. Based on these partitioning data, we explored the pairs of possible liquid outer core and solid inner core compositions in the Fe-Si-S +/- H +/- O system, which account for their respective seismological observations of the density and velocities. For the temperature at the inner core boundary of 5400 K, we obtained Fe + Ni + 2.7-3.0 wt% Si + 1.7 wt% S (fixed) + 0.32-0.59 wt% H + 0.05-2.5 wt% O for the outer core and Fe + Ni + 2.5-2.8 wt% Si + 0.69-0.70 wt% S + 0.23-0.43 wt% H for the inner core.
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Salles, T., Husson, L., Lorcery, M., & Hadler Boggiani, B. (2023). Landscape dynamics and the Phanerozoic diversification of the biosphere. Nature, 624(7990), 115–121.
Résumé: The long-term diversification of the biosphere responds to changes in the physical environment. Yet, over the continents, the nearly monotonic expansion of life started later in the early part of thePhanerozoiceon1 thanthe expansion in the marine realm, where instead the number of genera waxed and waned over time2. A comprehensive evaluation of the changes in the geodynamic and climatic forcing fails to provide a unified theory for the long-term pattern of evolution of life on Earth. Here we couple climate and plate tectonics models to numerically reconstruct the evolution of the Earth's landscape over the entire Phanerozoic eon, which we then compare to palaeo-diversity datasets from marine animal and land plant genera. Our results indicate that biodiversity is strongly reliant on landscape dynamics, which at all times determine the carrying capacity of both the continental domainand theoceanic domain. In the oceans, diversity closely adjusted to the riverine sedimentary flux that provides nutrients for primary production. On land, plant expansion was hampered by poor edaphic conditions until widespread endorheic basins resurfaced continents with a sedimentary cover that facilitated the development of soil-dependent rooted flora, and the increasing variety of the landscape additionally promoted their development.
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Salles, T., Husson, L., Rey, P., Mallard, C., Zahirovic, S., Boggiani, B. H., et al. (2023). Hundred million years of landscape dynamics from catchment to global scale. Science, 379(6635), 918–922.
Résumé: Our capability to reconstruct past landscapes and the processes that shape them underpins our understanding of paleo-Earth. We take advantage of a global-scale landscape evolution model assimilating paleoelevation and paleoclimate reconstructions over the past 100 million years. This model provides continuous quantifications of metrics critical to the understanding of the Earth system, from global physiography to sediment flux and stratigraphic architectures. We reappraise the role played by surface processes in controlling sediment delivery to the oceans and find stable sedimentation rates throughout the Cenozoic with distinct phases of sediment transfer from terrestrial to marine basins. Our simulation provides a tool for identifying inconsistencies in previous interpretations of the geological record as preserved in sedimentary strata, and in available paleoelevation and paleoclimatic reconstructions.
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Santamaria, S., Quidelleur, X., Samaniego, P., Audin, L., Le Pennec, J. - L., Hidalgo, S., et al. (2023). Timing of Quaternary volcanism and its relationship with tectonics in the central segment of the Ecuadorian Andes. Journal Of Volcanology And Geothermal Research, 442.
Résumé: The unusually high number of volcanoes in the Ecuadorian Arc, located in the deformation zone of the continental North Andean Sliver, coincides with the projection of the major oceanic structures observed in the Nazca Plate, such as the Carnegie Ridge and the Grijalva fracture zone. Although the relationship between this tectonic setting and volcanism has been widely discussed in the literature, their temporal relationship has not been thoroughly investigated due to the lack of geochronological data. We present here 20 new K-Ar and 2 40Ar/39Ar ages obtained for 7 volcanoes of the central segment of the Ecuadorian arc, which together with previous data show that volcanism in this area started at -1.3 Ma. A notable increase in volcanic activity occurred since -0.6 Ma, when the formation of a dozen volcanoes occurred in a relatively small area of the central segment. While this arrangement of volcanoes, here referred to as a “volcanic cluster”, appears to be controlled by crustal tectonic structures, the order of onset of these volcanoes and their eruptive activity does not show clear migration patterns over time. However, the presence of older volcanoes in the north of the central segment suggests a possible southward extension of volcanism between -1.3 and – 0.6 Ma. Finally, based on the cumulative bulk volumes calculated for the volcanic edifices over time, we infer that the magmatic productivity rate has been roughly constant during the last -550 kyr in this area.
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Schmitt, B., Souidi, Z., Duquesnoy, F., & Donze, F. - V. (2023). From RGB camera to hyperspectral imaging: a breakthrough in Neolithic rock painting analysis. Heritage Science, 11(1).
Résumé: Rock paintings undergo physical, chemical, biological and/or anthropic alterations that alter their visibility. Cameras and image enhancement tools -(DStretch((R)) plug-in, for example) are commonly used to help identify and record images that have become invisible to the naked eye. HyperSpectral Imaging (HSI) which is strongly developing in many research and application fields, is tested in this study to analyze Neolithic rock paintings. We particularly address the question of what kind of additional information can Visible Near InfraRed HSI instruments, coupled to mathematical transformations to reduce the dimensionality of the data, bring for rock paintings, compared to standard RGB cameras. From the analysis of a selection of panels painted on yellow-reddish altered sandstone walls and measured in Saharan shaded shelters, we show that HSI can reveal new figures by capitalizing both on its ability to extract the different pigment types with a greater contrast, and on the new discriminating information contained in the very near infrared part of the spectrum. Despite their much smaller image format, HSI can provide up to 5-7 contrasted images of the spatial distribution of the different types of pigments in the figures. It thus appears to be a promising non-invasive and efficient methodology to both reveal disappeared paintings and to study image juxtapositions and painted layer superimpositions.
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Schwaiger, T., Jault, D., Gillet, N., Schaeffer, N., & Mandea, M. (2023). Local estimation of quasi-geostrophic flows in Earth's core. Geophysical Journal International, 234(1), 494–511.
Résumé: The inference of fluid motion below the core-mantle boundary from geomagnetic observations presents a highly non-unique inverse problem. We propose a new method that provides a unique local estimate of the velocity field, assuming quasi-geostrophic flow in the core interior (which implies equatorial mirror symmetry) and negligible magnetic diffusion. These assumptions remove the theoretical underdetermination, enabling us to invert for the flow at each point of a spherical grid representing the core surface. The unreliable reconstruction of small-scale flows, which arises because only large-scale observations are available, is mitigated by smoothing the locally estimated velocity field using a Gaussian process regression. Application of this method to synthetic data provided by a state-of-the-art geodynamo simulation suggests that using this approach, the large-scale flow pattern of the core surface flow can be well reconstructed, while the flow amplitude tends to be underestimated. We compare these results with a core flow inversion using a Bayesian framework that incorporates statistics from numerical geodynamo models as prior information. We find that whether the latter method provides a more accurate recovery of the reference flow than the local estimation depends heavily on how realistic/relevant the chosen prior information is. Application to real geomagnetic data shows that both methods are able to reproduce the main features found in previous core flow studies.
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Senapati, B., Kundu, B., Perfettini, H., Gahalaut, V. K., Singh, A. K., Ghosh, A., et al. (2023). Fault resonance process and its implications on seismicity modulation on the active fault system. Tectonophysics, 861.
Résumé: Various periodic external loading processes (e.g., snow, hydrological and atmospheric, earth tide and surface reservoir load, etc.) affect tectonic deformation and sometimes modulate seismicity in diverse tectonic settings. Small stress variations induced by external loads may influence the fault dynamics and destabilize fault zones. In this article, we report five cases of earthquake occurrence in the plate boundary and plate interior regions where such a destabilization seems to be operating. We test the possibility of resonance amplification assuming rate -and-state friction and look for the model parameters that could justify resonance destabilization. We find that frictional resonance destabilization is possible in regions that are near the stability boundary (velocity neutral areas). The critical slip distance for the evolution of friction is similar to laboratory estimates. In some cases, effective normal stress lower than the lithostatic stress have to be assumed for the model to be consistent with the observations, implying high pore pressure. We propose that crustal faults of conditionally stable frictional do-mains with anomalous pore pressure are sensitive to periodic stress perturbations by the external loading process.
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Sethanant, I., Nissen, E., Pousse-Beltran, L., Bergman, E., & Pierce, I. (2023). The 2020 Mw 6.5 Monte Cristo Range, Nevada, Earthquake: Anatomy of a Crossing-Fault Rupture through a Region of Highly Distributed Deformation. Bulletin Of The Seismological Society Of America, 113(3), 948–975.
Résumé: The 15 May 2020 Mw 6.5 Monte Cristo Range earthquake (MCRE) in Nevada, United States, is the largest instrumental event in the Mina deflection-a zone of east-trending left-lateral faults accommodating a right step between northwest-trending right-lateral faults of the Walker Lane. The MCRE ruptured a highly distributed faulting area with muted geomorphic expressions, motivating us to characterize the behavior of an earthquake on a structurally immature fault system. Inverse modeling of Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) displacements reveals left-lateral slip on an east-striking, eastern fault and left-lateral-normal slip on an east-northeast-striking, western fault. Unusually, the two faults cross one another and ruptured together in the mainshock. The maximum slip of 1 m occurs at 8-10 km depth, but less than 0.1 m of slip reaches the surficial model fault patches, yielding a pronounced shallow slip deficit (SSD) of 91%. Relocated hypocenters indicate that the mainshock initiated at 9 km depth and that aftershocks span depths of 1-11 km, constraining the local seismogenic thickness. Our new field observations of fracturing and pebble-clearing in the western MCRE characterize a third, shorter, northern fault that is at the resolution limit of the InSAR-GNSS modeling. The segmented and intersecting fault geometry, off-fault aftershocks with variable mechanisms, distributed surface fractures, limited long-term geomorphic offsets, and a 600-700 m (cumu-lative) bedrock offset are all characteristic of a structurally immature fault system. However, the large SSD is not unusual for an earthquake of this magnitude, and a larger compilation of InSAR models (28 Mw >= 6:4 strike-slip events) shows that SSDs correlate with magnitude rather than structural maturity. This study demonstrates the importance of integrating geodesy, seismology, and field observations to capture the full complexity of large earth-quakes, and further suggests that seismic hazard assessments in shattered crustal regions consider the potential for multi-and cross-fault rupture.
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Sheng, Y. (2023). Seismic stereometry: an alternative two-station algorithm to seismic interferometry for analysing car-generated seismic signals. Geophysical Journal International, 235(1), 853–861.
Résumé: Human activities generate seismic waves, which have been traditionally analysed by seismic interferometry. However, this processing technique often neglects the seismic source distribution and is prone to introducing biases in interpretations. This study proposes an alternative processing technique known as seismic stereometry to analyse seismic signals generated by cars. The proposed algorithm exploits the highly coherent wavefields recorded by dense seismic arrays and directly measures the seismic wave traveltime differences between sensors. By doing so, it intrinsically considers the seismic source distribution. Traveltime differences can be used to invert the positions of vehicles and the near-surface velocity structures. We demonstrate the analysis using a dense seismic array deployed atop a southern San Andreas Fault segment and invert the shallow S-wave velocity using seismic waves generated by only one car. The velocity inversion result reveals a clear contrast across the fault, consistent with previous studies. The developed technique, combined with the distributed acoustic sensing technology, has great potential for applications in the urban environment.
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Shible, H., Hollender, F., Traversa, P., & Bard, P. - Y. (2023). Ground-Motion Model for Hard-Rock Sites by Correction of Surface Recordings (Part 1): Comparison of Site-Response Estimates at KiK-Net Sites. Bulletin Of The Seismological Society Of America, 113(5), 2164–2185.
Résumé: Site-specific seismic hazard assessment involves the prior knowledge of (1) the input ground motion at the local bedrock and (2) the site response. In this article and its companion, we address the deconvolution approach to obtain a reference ground-motion model, which consists of removing site effects from surface ground-motion recordings. Laurendeau et al. (2018) applied this approach on the KiK-net network with site response from 1D SH-wave (1DSH) simulations, calculated using the VS profiles available for most sites. Indeed, this approach presents several limitations with 1DSH site response if it is considered to be applied to other networks, especially in the European context. First, the approach requires identification of sites with dominant 1D effects. Second, it needs the presence of accurately measured VS profiles. In this context, we propose to derive deconvolved ground-motion models using site response from generalized inversion techniques () for two main reasons. The first reason is that the GIT delivers empirical site response for all types of sites, conditioned by the presence of sufficient amount of data, and the second is that it reduces the need for VS profiles. We focus on the estimation of site effects from different approaches and present a methodology to obtain reliable site terms from GIT based on the experience from previous studies. We also introduce and detail the difference between absolute and relative site response, which mainly depends on the chosen reference. We estimate and compare site response for the KiK-net stations with different methods, that is, empirical and theoretical 1DSH. We also conclude a list of 1D sites based on comparisons between theoretical and empirical estimates of site response. The results obtained in this article will be the primary input for the deconvolution approach applied in the companion article.
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Shible, H., Traversa, P., Hollender, F., & Bard, P. - Y. (2023). Ground-Motion Model for Hard-Rock Sites by Correction of Surface Recordings (Part 2): Correction, Mixed-Effects Regressions, and Results. Bulletin Of The Seismological Society Of America, 113(5), 2186–2210.
Résumé: In the framework of site-specific seismic hazard assessment, the definition of reference motion is a crucial step. Reference motion is generally associated with hard-rock conditions, characterized by S-wave velocity exceeding 1500 m/s. However, ground motion recorded at sites with such conditions is poorly represented in existing strong-motion data-bases. Thus, the validity domains of most empirical ground-motion prediction equations (GMPEs) are not representative of reference rock conditions. To overcome this limitation and assess ground motion at reference conditions, the so-called “deconvolution approach” was proposed by Laurendeau et al. (2018) to correct surface recordings from theoretical 1DSH site response before GMPE developments. With the same purpose, in this article, we propose to apply the deconvolution approach using empirical site-response estimates as an alternative to theoretical ones. Using the Kiban-Kyoshin network (KiK-net) data, we estimate empirical site responses at KiK-net stations using generalized inversion techniques in addition to those from 1DSH numerical simulations, as presented in the companion article. Finally, a reference ground-motion model (RGMM) is determined based on empirically deconvolved ground motions. The advantage of using empirical rather than 1DSH site responses in the deconvolution approach is that in the former case the RGMM can be built based on records from an extensive set of sites, whereas the latter case is restricted to well-characterized sites with dominant 1D behavior. This makes the proposed approach easily exportable to different regions of the world, where precise site characterizations are not systematically available, and the knowledge of site behavior is limited.
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Shim, S. - H., Ko, B., Sokaras, D., Nagler, B., Lee, H. J., Galtier, E., et al. (2023). Ultrafast x-ray detection of low-spin iron in molten silicate under deep planetary interior conditions. Science advances, 9(42), eadi6153.
Résumé: The spin state of Fe can alter the key physical properties of silicate melts, affecting the early differentiation and the dynamic stability of the melts in the deep rocky planets. The low-spin state of Fe can increase the affinity of Fe for the melt over the solid phases and the electrical conductivity of melt at high pressures. However, the spin state of Fe has never been measured in dense silicate melts due to experimental challenges. We report detection of dominantly low-spin Fe in dynamically compressed olivine melt at 150 to 256 gigapascals and 3000 to 6000 kelvin using laser-driven shock wave compression combined with femtosecond x-ray diffraction and x-ray emission spectroscopy using an x-ray free electron laser. The observation of dominantly low-spin Fe supports gravitationally stable melt in the deep mantle and generation of a dynamo from the silicate melt portion of rocky planets.
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Shishkina, T. A., Anosova, M. O., Migdisova, N. A., Portnyagin, M. V., Sushchevskaya, N. M., & Batanova, V. G. (2023). Trace Elements in Olivine of Volcanic Rocks: Application to the Study of Magmatic Systems. Geochemistry International, 61(1), 1–23.
Résumé: A quantitative local analytical method with the application of inductively coupled plasma mass spectrometry with laser ablation (LA-ICP-MS) was tested at Vernadsky Institute for the determination of contents of trace elements (Cu, Zn, Co, Ni, Mn, Cr, Sc, V, Ca, Ti, Al, Y, and REE) in olivine. Olivine phenocrysts from volcanic rocks of various geological settings have been studied: island-arc basalts, mid-ocean ridge (MOR) basalts, and high-alkaline continental volcanic rocks. The contents of some elements (Ni, Co, Mn, Cr, Sc, and Zn) systematically vary during the evolution of the composition of olivine, and the concentration fields of these elements in olivine from different settings overlap one another. At the same time, the contents of some other elements (Ca, Al, Ti, V, and Cu) fundamentally differ in olivine from different geological settings. Copper content in olivine from oceanic tholeiites and highly alkaline continental volcanics is 1-3 ppm, which is systematically lower than copper content in olivine from island-arc basalts (3-9 ppm). The concentrations of vanadium in olivine in MOR basalts are higher than in island-arc and alkaline continental ones, which may be due to relatively more reduced crystallization conditions as more favorable for the incorporation of V3+ into the olivine structure. Variations in the distribution coefficients of trace elements between olivine and silicate melt () were determined for volcanic rocks from Kamchatka, the Bouvet Triple Junction, and Gaussberg volcano. It has been demonstrated that the unusually high values of = 50-150 previously identified for the lamproites of Gaussberg volcano indicate a mismatch between the composition of the quenched glass and the composition of the equilibrium melt for olivine phenocrysts. When using the bulk compositions of Gaussberg rocks, values of = 11-21 were obtained, which correspond to experimental estimates for high-potassium rocks. The redox crystallization conditions of the studied rocks were estimated using several oxybarometers based on the distribution of vanadium between coexisting olivine and melt. These values were:.triangle QFM= +0.6 to +1.5 for oceanic tholeiites of the Bouvet Triple Junction area, South Atlantic, and.triangle QFM = +1.5 to +2.4 for Mutnovsky volcano, Kamchatka. Estimates of the redox crystallization conditions of the highly alkaline rocks of Gaussberg volcano significantly vary depending on which model is chosen:.triangle QFM= +0.2 to +4.8, which may be due to the strong effect of K2O content in the melt involved in one of the models. The newly acquired analytical data confirmed the possibility of using contents of trace elements in olivine to characterize igneous systems from different geological settings and highlighted the need for additional experimental studies on the distribution of these elements between olivine and melt, especially in highly alkaline systems. [GRAPHICS]
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Shmeit, M., Chauvel, C., Giraud, F., Jaillard, E., Reboulet, S., Masrour, M., et al. (2023). Geochemical and radiogenic isotope records of the Weissert Event in south Tethyan sediments. Journal Of The Geological Society, 180(3).
Résumé: The Cretaceous marine sedimentary record is characterized by time intervals rich in organic matter correlating with positive carbon isotope excursions, often called oceanic anoxic events. The Weissert Event corresponds to the first such event in the Cretaceous during the Valanginian stage. The associated palaeoenvironmental perturbations, which include increasing marine surface water primary productivity, are hypothesized to have been triggered by volcanic activity from large igneous provinces, and the source of nutrients is not well constrained (continental runoff v. oceanic upwelling). We present isotope ratios of Pb, Sr and Nd, together with concentrations of major and trace elements, for sediments from the central Moroccan margin to test these hypotheses. We demonstrate that the nutrient input was dominated by continental weathering. The source of sedimentary material remained stable during the Valanginian interval and originated from an old source, probably the African Sahara region. The radiogenic isotope signatures do not show a significant contribution of volcanic products from any known Valanginian large igneous province to the geochemical budget of sediments deposited on the central Moroccan margin. Although this does not preclude an impact of volcanic activity on the composition of seawater, it demonstrates that the erupted volumes were not sufficient to affect the deposited sediments.
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Sippl, C., Schurr, B., Muenchmeyer, J., Barrientos, S., & Oncken, O. (2023). The Northern Chile forearc constrained by 15 years of permanent seismic monitoring. Journal Of South American Earth Sciences, 126.
Résumé: In this review article, we compile seismological observations from the different constituent parts of the Northern Chile forearc: the downgoing Nazca Plate, the plate interface, the upper South American Plate as well as the mantle wedge beneath it. As Northern Chile has been monitored by a network of permanent seismic stations since late 2006, there is a wealth of observations that enables us to characterize the structure as well as ongoing processes in the forearc throughout the last 15 years. We put an emphasis on the analysis of seismicity, for which we have extended a massive earthquake catalog that now contains >180,000 events for the years 2007-2021. Moreover, we draw on published results for earthquake mechanisms, source properties, seismic velocity structure, statistical seismology and others, and discuss them in context of results from neighboring disciplines. We thus attempt to provide a comprehensive overview on the seismological knowledge about the structure and ongoing processes in the Northern Chile forearc, a breviary of which is found in the following: The Northern Chile megathrust hosted two major earthquake sequences during the analyzed time period. The 2007 M-w 7.8 Tocopilla earthquake broke the deep part of the megathrust just north of Mejillones Peninsula, whereas the 2014 M-w 8.1 Iquique earthquake ruptured the central segment in the north of the study region. The latter event has a highly interesting preparatory phase, including a significant foreshock sequence as well as aseismic slip transients. Besides these large events, background seismicity elsewhere on the megathrust may be helpful for characterizing the earthquake potential and locking state in the remaining seismic gap. The downgoing Nazca Plate in Northern Chile exhibits very high seismicity rates, with the vast majority of earthquakes occurring at depths of similar to 80-140 km with downdip extensive mechanisms. While seismic tomography shows no sudden changes in slab geometry along strike, seismicity describes peculiar offsets that may be linked to subducted features on the oceanic plate. Upper plate seismicity likewise shows strong variations along strike, with the north and south of the study area showing only weak activity, whereas the central segment shows pervasive microseismicity throughout the upper plate, all the way to the plate interface. These earthquakes have thrust and strike-slip mechanisms with P-axes striking roughly N-S, indicating margin-parallel compression that may be connected to the concavity of the margin.
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Skoblenko(Pilitsyna), A. V., Kanygina, N. A., Dubenskiy, A. S., Batanova, V. G., Dilek, Y., Sheshukov, V. S., et al. (2023). High-pressure metamorphism of Precambrian continental crust in the southwestern part of the Central Asian Orogenic Belt (South Kazakhstan and North Tien Shan) and tectonic implications for the evolution of the Palaeo-Asian Ocean. Geological Magazine, 160(8), 1624–1648.
Résumé: In this study, we investigated the high-pressure (HP) metamorphism of the Precambrian continental crust exposed in the Zheltau terrane in South Kazakhstan (Koyandy complex) and the Chu-Kendyktas terrane in the North Tien Shan of Kyrgyzstan (Aktyuz, Kemin and Kokdzhon complexes) within the SW part of the Central Asian Orogenic Belt. HP quartz-feldspar lithologies of the Koyandy complex consist of migmatized kyanite-bearing garnet-mica paragneisses, garnet-kyanite paragneisses and their derivatives associated with eclogites. Paragneisses demonstrate prograde evolution involving mica dehydration melting and producing magnesium-rich garnet, kyanite and K-feldspar at the near-peak to retrograde stages at pressures of 15-18.5 kbar and temperatures of 800-870(degrees)C. The widespread growth of micas in these rocks reflects lower stages of retrogression at P = 10-12 kbar and T = 720-770(degrees)C. The age distributions of the cores of detrital zircon grains from the paragneisses indicate a predominance of Neoproterozoic and minor occurrence of Mesoproterozoic and Palaeoproterozoic sources of their protoliths. The ages of similar to 487-485 Ma obtained from the zircon rims of the paragneisses reflect the timing of their HP metamorphic re-equilibration. These age clusters are consistent with the age estimates obtained from the rims of zircons in the eclogite-bearing garnet gneisses of the adjacent Aktyuz complex in the North Tien Shan. The P-T paths and zircon ages obtained from the high-grade quartz-feldspar gneisses of the Zheltau and Chu-Kendyktas terranes are thus interpreted to indicate involvement of the crustal material derived from the Precambrian basement (magmatic zircons aged ca. 844 Ma) and its Ediacaran-Cambrian sedimentary cover (detrital zircons with maxima at 1 Ga and 800-600 Ma) in the latest Cambrian subduction processes induced by the closure of the oceanic basins assigned to the Palaeo-Asian Ocean.
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Soergel, D., Pedersen, H. A., Bodin, T., Paul, A., & Stehly, L. (2023). Bayesian analysis of azimuthal anisotropy in the Alpine lithosphere from beamforming of ambient noise cross-correlations. Geophysical Journal International, 232(1), 429–450.
Résumé: Surface waves extracted from ambient noise cross-correlations can be used to study depth variations of azimuthal anisotropy in the crust and upper mantle, complementing XKS splitting observations. In this work, we propose a novel approach based on beamforming to estimate azimuthal anisotropy of Rayleigh wave phase velocities extracted from ambient noise cross-correlations. This allows us to identify and remove measurements biased by wave front deformation due to 3-D heterogeneities, and to properly estimate uncertainties associated with observed phase velocities. In a second step, phase velocities measured at different periods can be inverted at depth with a transdimensional Bayesian algorithm where the presence or absence of anisotropy at different depths is a free variable. This yields a comprehensive probabilistic solution that can be exploited in different ways, in particular by projecting it onto a lower dimensional space, appropriate for interpretation. For example, we show the probability distribution of the integrated anisotropy over a given depth range (e.g. upper crust, lower crust). We apply this approach to recent data acquired across the AlpArray network and surrounding permanent stations. We show that only the upper crust has a large-scale coherent azimuthal anisotropy at the scale of the Alps with fast axis directions parallel to the Alpine arc, while such large-scale patterns are absent in the lower crust and uppermost mantle. This suggests that the recent Alpine history has only overridden the anisotropic signature in the upper crust, and that the deeper layers carry the imprint of older processes. In the uppermost mantle, fast directions of anisotropy are oriented broadly north-south, which is different from results from XKS-splitting measurements or long-period surface waves. Our results therefore suggest that XKS observations are related to deeper layers, the asthenosphere and/or subduction slabs. The area northwest of the Alps shows strong anisotropy in the lower crust and uppermost mantle with a fast axis in the northeast direction that could be related to Variscan deformation.
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Sonnet, M., Labrousse, L., Bascou, J., Plunder, A., Nouibat, A., & Paul, A. (2023). Assessing Chemical and Mineralogical Properties of the Alpine Slab Based on Field Analogs and Ambient Noise Tomography. Geochemistry Geophysics Geosystems, 24(12).
Résumé: Recent geophysical campaigns in the Alps produce images with seismic property variations along the slab of sufficiently fine resolution to be interpreted as rock transformations. Since the reacting European lower crust is presumed responsible for the variations of velocities at the top of the Alpine slab, we sampled local analogs of the lower crustal lithologies in the field and modeled the evolution of equilibrium seismic properties during burial, along possible pressure-temperature paths for the crustal portion of the slab. The results are then compared to the range of the S-wave velocities obtained from the S-wave velocity tomography model along the CIFALPS transect. The velocity increase from 25 to 45 km within the slab, in the tomographic model is best reproduced by the transformation of specific lithologies in the high-pressure granulite facies along a collisional gradient (30 degrees C/km). Although the crust is certainly not completely homogeneous, the best candidates for the rocks that make up the top of the Alpine dip crustal panel are a kinzigite from Monte San Petrone, a gneiss from the Insubric line, and blueschist mylonite from Canavese. While they may not represent the entirety of the crust, they are sufficient to explain the tomographic velocity of the Alpine slab. A lateral lithological contrast inherited from the Variscan orogeny is not required. Eclogitization, suggested as the first-order transformation in convergence zones, could be a second-order transformation in collisional wedges. These results also imply a partially re-equilibrated thermal gradient, consistent with the Alpine thermal state data at depth. Tomography, that is, imaging of deep geological structures based on seismic wave travel to time anomalies, is now so sensitive that it allows us to see changes in the properties of rocks buried at depth beneath mountain belts. In the Alps, the European plate is imaged down to 80 km and shows a sharp velocity increase close to 30 km depth. By calculating the bulk seismic wave velocities on exhumed analogs sampled throughout the Western Alps, the present study proposes to interpret the velocity jump as the consequence of the transformation of the European lower crust from amphibolite to granulite (the high-temperature metamorphic rocks produced during a collision) rather than the usually admitted transformation to eclogite (the higher pressure metamorphic rocks produced during subduction). This has implications regarding the present-day thermal structure of the Alps: the Western Alps are not a frozen subduction zone but a collision zone exposing subduction-related rocks and structures at the surface only. The lower crustal top of the European Alpine slab is mostly composed of felsic to intermediate rocksThe transformation of hydrated rocks into HP granulites along a collision gradient reproduces the slab tomographic velocity increase at 30 kmThe often-supposed eclogitization produces velocities that are significantly higher than the crustal top of the European Alpine slab
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Stigliano, L., Ackerer, P., Benzerara, K., & Daval, D. (2023). Linking calcite surface roughness resulting from dissolution to the saturation state of the bulk solution. Chemical Geology, 637.
Résumé: It has long been supposed that mineral dissolution results in surface microtopography features that may be related to the weathering conditions. Detection of etch pits on weathered mineral surfaces is indicative of far-from-equilibrium conditions (O?0), whereas their absence points towards close-to-equilibrium conditions (O?1). However, surface microtopography characterizations limited solely to qualitative comparisons may conceal the potential of reconstructing intermediate saturation conditions. To investigate this prospect, we performed flow-through dissolution experiments at room temperature and atmospheric pCO(2), on mechanically-polished {104} calcite surfaces reacting at different saturation states with respect to calcite (0 = O =0.8), under alkaline conditions (pH = 7.9). Time-resolved topography data of the dissolved calcite surface were acquired ex situ using vertical scanning interferometry (VSI). Quantitative comparisons of the ensuing surface topography data relied on surface roughness characterizations, based on a combination of unidimensional descriptors (R-a) and spatial statistics metrics (power spectral density, or PSD, and semi-variogram). Time-resolved surface roughness analyses suggested a temporal stabilization of the calcite surfaces undergoing dissolution for all targeted saturation states, and that the steady-state surface roughness evaluations corresponding to different O values are statistically distinguishable, with larger roughness values corresponding to lower O values, according to a seemingly bijective relationship. We then investigated the atomic-scale mechanisms that might partially explain the empirical O-roughness relationship derived experimentally at the VSI-scale through kMC and Ising dissolution modeling of a Kossel crystal. We found that the Ising model successfully reproduced the O-roughness behavior observed experimentally, and we discussed the features that interpretative stochastic models need to satisfy to agree with the experimental findings. Overall, the present study suggests that, under the investigated conditions, the steady-state calcite surface roughness resulting from dissolution can be used as a proxy to back-estimate the saturation state of the fluid under which the reaction occurred for samples reacted under unknown conditions.
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Straub, S. M., Batanova, V., Sobolev, A., Gomez-Tuena, A., Espinasa-Perena, R., Fleming, W. L., et al. (2023). The Systematics of Olivine CaO plus Cr-Spinel in High-Mg# Arc Volcanic Rocks: Evidence for in-Situ Mantle Wedge Depletion at the Arc Volcanic Front. Journal Of Petrology, 64(12).
Résumé: We investigated the state of the arc background mantle (i.e. mantle wedge without slab component) by means of olivine CaO and its Cr-spinel inclusions in a series of high-Mg# volcanic rocks from the Quaternary Trans-Mexican Volcanic Belt. Olivine CaO was paired with the Cr# [molar Cr/(Cr + Al) *100] of Cr-spinel inclusions, and 337 olivine+Cr-spinel pairs were obtained from 33 calc-alkaline, high-K and OIB-type arc front volcanic rocks, and three monogenetic rear-arc basalts that lack subduction signatures. Olivine+Cr-spinels display coherent elemental and He-O isotopic systematics that contrast with the compositional diversity of the bulk rocks. All arc front olivines have low CaO (0.135 +/- 0.029 wt %) relative to rear-arc olivines which have the higher CaO (0.248 +/- 0.028 wt %) of olivines from mid-ocean ridge basalts. Olivine He-3/He-4-delta O-18 isotope systematics confirm that the olivine+Cr-spinels are not, or negligibly, affected by crustal basement contamination, and thus preserve compositional characteristics of primary arc magmas. Variations in melt H2O contents in the arc front series and the decoupling of olivine CaO and Ni are inconsistent with controls on the olivine CaO by melt water and/or secondary mantle pyroxenites. Instead, we propose that low olivine CaO reflects the typical low melt CaO of high-Mg# arc magmas erupting through thick crust. We interpret the inverse correlation of olivine CaO and Cr-spinel Cr# over a broad range of Cr# (similar to 10-70) as co-variations of CaO, Al and Cr of their (near) primary host melts, which derived from a mantle that has been variably depleted by slab-flux driven serial melt extraction. Our results obviate the need for advecting depleted residual mantle from rear- and back-arc region, but do not upset the larger underlying global variations of melt CaO high-Mgy# arc magmas worldwide, despite leading to considerable regional variations of melt CaO at the arc front of the Trans-Mexican Volcanic Belt.
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Suarez, R. J. J., Ramos, M. E. E., Sue, C., Ghiglione, M., Barberon, V., Quezada, P., et al. (2023). An assessment of dip-slip versus strike-slip faulting modes along the Patagonian Andes (39°-50° S) and their related orogenic models. International Geology Review, .
Résumé: The compilation of a database of 225 strain/stress tensors (accounting for similar to 4000 fault-striae data pairs) combined with evidence of syntectonic strata, and a seismotectonic appraisal along the Patagonian Andes (39 degrees-50 degrees S; South America), leads us to assess typical features of Mesozoic to current faulting in this segment of the Andean orogen. At the orogen scale, the fault-slip and focal mechanism database show the prevalence of strike-slip faulting, challenging the classic proposal for the Andean orogen of alternating extensional and contractional deformation phases. However, the wrenching tectonism in Cenozoic times may be explained through a strain partitioning model in the North Patagonian Andes by re-activating a large-scale, inherited anisotropy within the basement (namely the Liquine-Ofqui fault system), which is currently the locus of significant seismicity. On the other hand, a non-partitioned context allows explaining the Cenozoic patterns of brittle deformation the South Patagonian Andes. Our results highlight that the classifications of Andean-type orogens should integrate both inherited anisotropies and the heterogeneous distribution of strain across the upper plate in order to address complex patterns of deformation.
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Toubhans, B., Alkafri, N., Quintela, M., James, D. W., Bissardon, C., Gazze, S., et al. (2023). Selenium nanoparticles modulate histone methylation via lysine methyltransferase activity and S-adenosylhomocysteine depletion. Redox Biology, 61.
Résumé: At physiological levels, the trace element selenium plays a key role in redox reactions through the incorporation of selenocysteine in antioxidant enzymes. Selenium has also been evaluated as a potential anti-cancer agent, where selenium nanoparticles have proven effective, and are well tolerated in vivo at doses that are toxic as soluble Se. The use of such nanoparticles, coated with either serum albumin or the naturally occurring alkaline polysaccharide chitosan, also serves to enhance biocompatibility and bioavailability. Here we demonstrate a novel role for selenium in regulating histone methylation in ovarian cancer cell models treated with inorganic selenium nanoparticles coated with serum albumin or chitosan. As well as inducing thioredoxin reductase expression, ROS activity and cancer cell cytotoxicity, coated nanoparticles caused significant increases in histone methylation. Specifically, selenium nanoparticles triggered an increase in the methylation of histone 3 at lysines K9 and K27, histone marks involved in both the activation and repression of gene expression, thus suggesting a fundamental role for selenium in these epigenetic processes. This direct function was confirmed using chemical inhibitors of the histone lysine methyltransferases EZH2 (H3K27) and G9a/EHMT2 (H3K9), both of which blocked the effect of selenium on histone methylation. This novel role for selenium supports a distinct function in histone methylation that occurs due to a decrease in S-adenosylhomocysteine, an endogenous inhibitor of lysine methyltransferases, the metabolic product of methyl-group transfer from S- adenosylmethionine in the one-carbon metabolism pathway. These observations provide important new insights into the action of selenium nanoparticles. It is now important to consider both the classic antioxidant and novel histone methylation effects of this key redox element in its development in cancer therapy and other applications.
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Touma, R., Le Ber, A., Campillo, M., & Aubry, A. (2023). Imaging the Crustal and Upper Mantle Structure of the North Anatolian Fault: A Transmission Matrix Framework for Local Adaptive Focusing. Journal Of Geophysical Research-Solid Earth, 128(11).
Résumé: Imaging the structure of major fault zones is essential for our understanding of crustal deformations and their implications on seismic hazards. Investigating such complex regions presents several issues, including the variation of seismic velocity due to the diversity of geological units and the cumulative damage caused by earthquakes. Conventional migration techniques are in general strongly sensitive to the available velocity model. Here we apply a passive matrix imaging approach which is robust to the mismatch between this model and the real seismic velocity distribution. This method relies on the cross-correlation of ambient noise recorded by a geophone array. The resulting set of impulse responses form a reflection matrix that contains all the information about the subsurface. In particular, the reflected body waves can be leveraged to: (a) determine the transmission matrix between the Earth's surface and any point in the subsurface; (b) build a confocal image of the subsurface reflectivity with a transverse resolution only limited by diffraction. As a study case, we consider seismic noise (0.1-0.5 Hz) recorded by the Dense Array for Northern Anatolia that consists of 73 stations deployed for 18 months in the region of the 1999 Izmit earthquake. Passive matrix imaging reveals the scattering structure of the crust and upper mantle around the North Anatolian Fault zone over a depth range of 60 km. The results show that most of the scattering is associated with the Northern branch that passes throughout the crust and penetrates into the upper mantle. Investigating the structure of major fault zones is important to understand the deformations of the Earth's crust and their potential impact on future earthquakes. However, the large variations of seismic velocity between different geological units drastically hampers the ability to image those areas. The North Anatolian Fault is no exception since it splits into two branches separating three major geological blocks in the region of the 1999 Izmit earthquake. To image the deep structure of this fault, seismic noise is here exploited to retrieve information on the body waves reflected by the underground heterogeneities. A three-dimensional map of the subsurface reflectivity is then built by applying methods originally developed in optical microscopy and ultrasound for deep imaging inside complex media. The inner structure of the Earth around the North Anatolian Fault is revealed. In particular, the Northern branch is shown to exhibit a strong damage pattern and a deep penetration inside the upper mantle. A matrix approach of passive seismology provides 3D imaging of the North Anatolian Fault, Turkey, over a depth range of 60 kmTransmission matrix between the Earth surface and the underground is extracted by means of spatio-temporal correlations of seismic noiseTime reversal of this transmission matrix enables a sharp compensation of the seismic velocity variations in the fault area
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Truffet, B., Fiquet, G., Morard, G., Baron, M. A., Miozzi, F., Harmand, M., et al. (2023). High pressure dissociation of CaTiO3 perovskite into CaO and CaTi2O5. Physics Of The Earth And Planetary Interiors, 334.
Résumé: In this study, we investigated phase transformations of CaTiO3 perovskite using x-ray diffraction at high pressure and high temperature up to 170 GPa and 4500 K in a laser-heated diamond-anvil cell. We report a high-pressure dissociation of CaTiO3 into CaO-B2 and CaTi2O5 with a monoclinic P2/m structure, instead of the expected transformation of the orthorhombic distorted perovskite structure into a post-perovskite phase. We propose that this transition may be favored by the B1 to B2 phase change of CaO at around 60 GPa. In order to provide additional information on the high pressure properties of CaTiO3 perovskite, we measured its melting temper-ature using CO2 laser heated diamond anvil cell up to 55 GPa yielding a fit of the melting curve to a Kraut-Kennedy empirical law according to: Tm (K) = 2188 * [1 + 4.23 * (Delta V/V0)]. To provide some further insight into the thermodynamic properties of CaTiO3, we determined the P-V-T equation of state of the orthorhombic mineral perovskite, fitted by using a third order Birch-Murnaghan equation of state and a Berman thermal expansion model. The fit of the data yields to K0 = 180.6(4) GPa, K ' 0 = 4 (fixed), partial differential K/ partial differential T =-0.022(1) GPa K-1, alpha 1 = 3.25(5) x 10-5 K-1, alpha 2 = 1.3(1) x 10-8 K-2
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Tuduri, J., Pourret, O., Gloaguen, E., Lach, P., Janots, E., Colin, S., et al. (2023). Formation of authigenic grey monazite: A palaeo-thermal anomaly marker in very-low grade metamorphic rocks? Ore Geology Reviews, 160.
Résumé: Reassessment of France's rare earth element (REE) potential led us to investigate REE behaviour in the black shales of the Middle Ordovician Angers-Traveusot Formation in central Brittany (France). This study focuses on the distribution of nodular grey monazite (up to 200 g/t) within the shales, which formed in response to the diagenetic and low-grade metamorphic evolution of the studied area. Whole rock geochemistry, rock-eval pyrolysis and evolution of clay mineral crystallinity were firstly used to determine temperature and mass transfer conditions in the black shales. Then, monazite texture, composition and U-Pb in-situ dates were determined, and correlated with the diagenetic/anchimetamorphic conditions. Nodular monazite appears in the Ordovician black shales at the transition between high-grade diagenesis and the anchizone metamorphic facies, in response to processes controlled by competing influences such as organic matter maturation, Fe oxide/hydroxide reduction and clay transformation with accompanying fluid release. Monazite occurs mainly as elongated nodules, up to 2 mm in diameter that are characterised by their grey colour caused by an abundance of host-rock mineral inclusions. Monazite nodule compositions are zoned with Nd and middle REE-rich cores surrounded by Ce-rich rims, with no evidence of inherited domains. Ce-monazite also occurs as a replacement of nodular monazite or in late-stage fractures. Zoned nodular grey monazites were dated at ca. 403.6 +/- 2.9 Ma, which is proposed to record the high heat flux that led to the anchimetamorphic conditions found at the base of the Angers-Traveusot formation, prior to the Variscan deformation. Crystallisation of the metamorphic Ce-monazite occurred at two periods, dated at 382.6 +/- 2.9 Ma and 349.6 +/- 6 Ma, which correspond to pre-collisional and collisional tectonometamorphic stages respectively. Nodular grey monazite constitutes an interesting alternative economic solution because of its very low content in both Th (X=2160 ppm) and U (X=145 ppm) and negligible radiological impact if mined. However, placers currently display a limited economical interest.
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Turuani, M. J., Seydoux-Guillaume, A. - M., Laurent, A. T., Reddy, S. M., Harley, S. L., Fougerouse, D., et al. (2023). Nanoscale features revealed by a multiscale characterisation of discordant monazite highlight mobility mechanisms of Th and Pb. Contributions To Mineralogy And Petrology, 178(5).
Résumé: Understanding radionuclides mass transfer mechanisms in monazite (LREEPO4) and the resulting features, from the micro- to the nanoscale, is critical to its use as a robust U-Th-Pb geochronometer. A detailed multiscale characterisation of discordant monazite grains from a granulite which records a polymetamorphic history explores the mechanisms of Th and Pb mobility in crystals. Some monazite grains display Th-rich linear features (0.1-1 μm thick) forming a regular network throughout the grain. They are interpreted as resulting from fluid ingress along crystallographically controlled pathways. Nanoscale features termed 'clusters' (o < 10 nm) are composed of radiogenic Pb (Pb*) +/- Si +/- Ca and are localised within monazite lattice defects. Their formation results from the competition, over millions of years, of both radiation damage production allowing element mobility (by diffusion) and accumulation in defects and alpha-healing inducing their trapping. Nanophases (o = 0.02-1 μm) containing Pb* are present in all grains and correspond to galena (PbS) or sesquioxide of Pb (Pb2O3). They are associated with a chemically varied suite of amorphous silicate (+/- Al, Mg, Fe) phases or sulphur (e.g. FeS). They are interpreted as precipitates within monazite crystals. They are formed during replacement mechanism of monazite through fluid interactions. Two generations of Pb*-bearing nanophases exist supported by previous geochronological data. The shielding effect of garnet and rutilated quartz (host minerals), limiting fluid access, induces plentiful Pb*-bearing nanophases precipitation (fluid saturation enhanced) and limits Pb*-loss at the grain scale. This multiscale study provides new insights for interpretations of meaningless geochronological information, thanks to nanoscale investigations.
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Umlauft, J., Johnson, C. W., Roux, P., Trugman, D. T., Lecointre, A., Walpersdorf, A., et al. (2023). Mapping Glacier Basal Sliding Applying Machine Learning. Journal Of Geophysical Research-Earth Surface, 128(11).
Résumé: During the RESOLVE project (“High-resolution imaging in subsurface geophysics: development of a multi-instrument platform for interdisciplinary research”), continuous surface displacement and seismic array observations were obtained on Glacier d'Argentiere in the French Alps for 35 days in May 2018. The data set is used to perform a detailed study of targeted processes within the highly dynamic cryospheric environment. In particular, the physical processes controlling glacial basal motion are poorly understood and remain challenging to observe directly. Especially in the Alpine region for temperate based glaciers where the ice rapidly responds to changing climatic conditions and thus, processes are strongly intermittent in time and heterogeneous in space. Spatially dense seismic and Global Positioning System (GPS) measurements are analyzed applying machine learning to gain insight into the processes controlling glacial motions of Glacier d'Argentiere. Using multiple bandpass-filtered copies of the continuous seismic waveforms, we compute energy-based features, develop a matched field beamforming catalog and include meteorological observations. Features describing the data are analyzed with a gradient boosting decision tree model to directly estimate the GPS displacements from the seismic noise. We posit that features of the seismic noise provide direct access to the dominant parameters that drive displacement on the highly variable and unsteady surface of the glacier. The machine learning model infers daily fluctuations and longer term trends. The results show on-ice displacement rates are strongly modulated by activity at the base of the glacier. The techniques presented provide a new approach to study glacial basal sliding and discover its full complexity.
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Vanderschueren, R., Wantiez, L., Blommaert, H., Flores, J., Chavez, E., & Smolders, E. (2023). Revealing the pathways of cadmium uptake and translocation in cacao trees (<i>Theobroma cacao</i> L.): A <SUP>108</SUP>Cd pulse-chase experiment. Science Of The Total Environment, 869.
Résumé: The pathways through which cadmium (Cd) is taken up and loaded into cacao beans (nibs) are yet to be revealed. Previous work suggested that Cd loading into cacao nibs may occur via direct xylem uptake rather than phloem-mediated redistribution from the leaves. A stable isotope (108Cd) pulse-chase experiment was set up to identify the pathways of Cd loading into cacao nibs. The topsoil beneath two mature cacao trees in the field was enriched in 108Cd via surface irrigation with a spiked solution. The increase in 108Cd isotopic abundance (IA) in the plant tissues was followed up for 548 days after spiking. The 108Cd IA in the plant tissues increased from natural abundance (0.89 %) to 7.0 % (tree A) and 10.1 % (tree B) at equilibrium. The tracer was taken up in the plant tissues in the order immature leaves > mature leaves > nibs in both trees, while tracer uptake in flowers and cherelles was less consistent between the trees. Half of the equilibrium 108Cd IA was reached in the nibs at 191 days after spiking, significantly later than corresponding values for mature (151 days) and immature leaves (117 days). Pod maturation from flower stage takes about 6 months with most Cd entering the nibs at the last stage of development. The rather slow rise in the 108Cd IA in the nibs compared to the leaves hence suggests that Cd in cacao nibs likely originates from phloem-redistribution from the stem, branches or mature leaves and not from direct root-to-nib transport via the xylem.
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Virieux, J., Paul, A., Langlais, M., Janex, G., Gueguen, P., Helmstetter, A., et al. (2023). Assessing the reliability of local earthquake tomography for crustal imaging: 30 yr of records in the Western Alps as a case study. Geophysical Journal International, 236(1), 99–118.
Résumé: Local earthquake tomography (LET) is a popular method for inverting arrival time picks of local-regional earthquakes for P- and S-wave velocities and hypocentre parameters in seismically active regions. This popularity is due to some robust and well-documented open-source codes that are sometimes used as black boxes. The availability of a very complete time-pick database on the Western Alps gives us a chance to thoroughly investigate the influence of the numerous processes and parameters involved when applying LET to the Western Alps or similar targets. From a subset of high-quality manual picks (1989-2014), we compute preliminary P and S velocity models that are used to predict arrival times for later events and allow the selected fusion of picks downloaded from different seismological agencies for a consistent 33-yr database (1989-2021). Different model reconstructions are proposed by selecting different subsets of the arrival time data set. Aside data input into the LET, influence of initial stratified or 3-D velocity models and related initial earthquake locations is investigated together with grid discretization, Laplacian smoothing and damping parameters in the standard penalty approach commonly used by LET codes. These numerical parameters account for the expected limited resolution of seismic waves due to their finite-frequency content. Parameter selection is handled by the user, whereas frequency impact is only implicit in the onset picks.The earthquake distribution allows a reconstruction down to 40-km depth over an area of similar to 500 x 500 km2. Robust features such as the high-velocity Ivrea body anomaly, and a deep low-velocity anomaly associated with crustal thickening underneath the mountain belt survive whatever the tomography strategy and parameters. Finally, a comparison with previous LET reconstructions suggests that finite-frequency content be explicitly incorporated through wave equation tomography to improve spatial resolution. This would fully exploit observables collected from seismograms, albeit with a significant increase in computer costs.
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Wang, J., Liu, Y., Yang, C., Zheng, Y., Jiang, W., Menegon, L., et al. (2023). Upscaling the creep behavior of clay-rich and quartz-rich shales from nanoindentation measurements: Application to the Wufeng-Longmaxi shale, China. International Journal Of Rock Mechanics And Mining Sciences, 171.
Résumé: Creep of shale controls the stability of fault gouge in sedimentary rocks, aseismic deformation in the upper crust, and several engineering operations, such as proppant embedment, reservoir subsidence, and wellbore stability during unconventional shale gas exploitation. However, measuring the creep properties of shale is challenging due to the multi-scale structure of this rock. Here, our goal is to assess how creep parameters measured at the core sample scale depend on those measured at the nanoscale in shales. We selected three clay-rich and quartzrich shale samples and conducted a series of experiments on shale samples at two scales: nanoindentation creep measurements on thin sections, and uniaxial creep tests on core samples. The creep parameters, including creep displacement (Delta h), indentation creep (CIT), creep strain rate sensitivity (m), contact creep modulus (C), and viscoelastic parameters (E1, E2, eta 1, and eta 2) of the Burgers' model, were calculated by fitting the nanoindentation creep data of each single-phase component of shale matrix. From these data, we upscale the creep parameters (E1, E2, and C) of shale matrix to those of the bulk shale. Upscaled E2 and C values based on the Mori-Tanaka scheme are found to be relatively close to those measured in previous microindentation study on Longmaxi shale and are consistent with our measurements in uniaxial creep tests on core samples of clay-rich shale and quartz-rich shale. The upscaling value of the elastic parameters, E1, is almost twice larger than the results from uniaxial creep test. We interpret this difference as due to low elastic stiffness along grain contacts of the shale that nanoindentation measurements underestimate. Our results show a consistency of some creep parameters upscaled from nanoindentation data and those measured at a macroscopic scale on core samples.
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Wang, T., Wautier, A., Zhu, J., & Nicot, F. (2023). Stabilizing role of coarse grains in cohesionless overfilled binary mixtures: A DEM investigation. Computers And Geotechnics, 162.
Résumé: Cohesionless binary mixtures are commonly encountered in nature and frequently used as filling materials in geotechnical engineering. It is known that coarse grains have a reinforcement effect on overfilled binary mixtures in which coarse grains are embedded in the matrix of fine-grains. However, the micromechanical origin of this reinforcement effect remains unknown. Using 2D discrete element method (DEM) simulations, this study aims at highlighting the impact of coarse grains on the geometrical fabric and mechanical state of cohesionless overfilled binary mixtures. We show that coarse grains contribute to the stability of cohesionless overfilled binary mixtures by limiting macroscopic plastic deformation. Coarse grains play the role of attractors of force chains, as they promote more connected contact force networks in overfilled binary mixtures. The results of micromechanical analyses further show that embedded coarse grains in overfilled binary mixtures have a long-range influence in the surrounding fine-grain matrix in the form of a “fine bridge,” which enables better stress transmission and improves the bearing capacity of the mixture.
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Weatherill, G., Crowley, H., Roulle, A., Tourliere, B., Lemoine, A., Gracianne, C., et al. (2023). Modelling site response at regional scale for the 2020 European Seismic Risk Model (ESRM20). Bulletin Of Earthquake Engineering, 21(2), 665–714.
Résumé: Quantitative estimation of seismic risk over a region requires both an underlying probabilistic seismic hazard model and a means to characterise shallow site response over a large scale. The 2020 European Seismic Risk Model (ESRM20) builds on the 2020 European Seismic Hazard Model (ESHM20), requiring additional information to firstly parameterise the local site condition across all of Europe, and subsequently determine its influence on the prediction of seismic ground motion. Initially, a harmonised digital geological database for Europe is compiled, alongside a model of topographic/bathymetric elevation and a database of 30 m averaged shearwave velocity measurements ( V-S30), in order to produce separate 30 arc-second maps of inferred V-S30 based on topography and on geology. We then capitalise on a large database of seismic recording stations in Europe for which site to-site ground motion residuals (delta S2S(S)) have been determined with respect to the shallow crustal ground motion model used in the ESHM20. These residuals allow us to incorporate site amplification functions into the European GMM calibrated upon either observed or inferred V-S30, or on the European geology and topography models. We present the resulting pan-European seismic site amplification model and assess its impact on seismic hazard and risk compared against other approaches. The new site amplification model fulfils the requirements of the ESRM20 and, providing uncertainty is fully propagated, yields estimates of seismic hazard and risk at a large space scale that may be comparable to other methods often applied at local/urban scale where better-constrained site information is available.
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Weiss, J., & Amitrano, D. (2023). Logarithmic versus Andrade's transient creep: Role of elastic stress redistribution. Physical Review Materials, 7(3).
Résumé: Creep is defined as time-dependent deformation and rupture processes taking place within a material subjected to constant applied stress smaller than its athermal, time-independent strength. This time dependence is classically attributed to the thermal activation of local deformation events. The phenomenology of creep is characterized by several ubiquitous but empirical rheological and scaling laws. We focus here on primary creep following the onset of loading, for which a power law decay of the strain rate is observed, epsilon similar to t(-p), with the exponent p varying between 0.4 and 1, this upper bound defining the so-called logarithmic creep. Although this phenomenology is known for more than a century, the physical origin of Andrade-like (p < 1) creep remains unclear and debated. Here we show that p < 1 values arise from the interplay between thermal activation and elastic stress redistribution. The latter stimulates creep dynamics from a shortening of waiting times between successive events, is associated to material damage and, possibly, at high temperature and/or stresses, gives rise to avalanches of deformation events.
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Wu, Z., Zhang, T., Lanson, B., Yin, H., Cheng, D., Liu, P., et al. (2023). Sulfidation of Ni-bearing goethites to pyrite: The effects of Ni and implications for its migration between iron phases. Geochimica Et Cosmochimica Acta, 353, 158–170.
Résumé: Goethite and pyrite are common iron minerals in oxic or anoxic environments, respectively, both minerals being major reservoirs for Nickel, a bio-essential element. Mineral transformation between goethite and pyrite is frequent owing to the alternation of oxic and anoxic conditions in sulfate-rich environments. This mineral transformation has been amply studied, but the effect of Ni on this transformation and its fate along it remain poorly understood. Sulfidation of Ni-free and Ni-containing (through adsorption or isomorphic substitution) goethites was thus studied experimentally by reacting goethite with dissolved S(-II) (molar Fe:S & AP;1:1). X-ray diffraction and associated Rietveld refinement, thermogravimetric analysis, scanning/transmission electron microscopy, X-ray absorption spectroscopy, and wet chemistry were used to monitor mineralogical evolutions and unravel Ni association with reaction products. After 44 days of sulfidation, about half of initial goethite converted to iron sulfides: thermodynamically stable pyrite (67%-93%) with minor contents of mackinawite (2%-15%) and greigite (5%-25%). Although the overall content of iron sulfides formed was essentially independent of Ni presence, Ni hampered the conversion from metastable iron sulfides (i.e., mackinawite and greigite) to pyrite (67%-78% vs. 93%, in the presence and absence of Ni, respectively). Pyrite formation from metastable sulfide precursors yielded a uniform Ni distribution in newly formed pyrite, regardless of the initial Ni association with goethite. Although no Ni was released to solution during pyrite formation, Ni incorporation to pyrite results in an increased risk of release to the environment as iron sulfides will be oxidized when exposed to air and water in supergene environments, leading to highly acidic conditions favoring Ni solubility and mobility.
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Xie, F., Larose, E., Wang, Q., & Zhang, Y. (2023). In-situ monitoring of rock slope destabilization with ambient seismic noise interferometry in southwest China. Engineering Geology, 312.
Résumé: The damage evolving on rock slopes, including unstable mass failure events, is expected to be associated with a rigidity loss of geomaterials. Therefore, velocity changes (dv/v) inferred from ambient noise interferometry allow remotely assessing the damage state of the slope. However, the time scale and amplitude of the dv/v evolution associated with the slope destabilizations are not well known, and their detection and characterization require both high precision and high temporal resolution in dv/v. We herein report an in-situ one-year monitoring of the dv/v on the slow-moving Pubugou rock slope with a high temporal resolution up to 20-min by using two seismic stations in the mountainous region of Sichuan, China, where the slope is affected by both earthquakes and rainfall. The results confirm the feasibility of (1) detecting a possible precursor dv/v drop (-0.5%) similar to 40 min before a slope destabilization; (2) characterizing the dv/v caused by the superimposed effects of moderate earthquakes and rainfall; and (3) quantifying the daily dv/v fluctuations of the slope caused by the environmental thermal forcing through thermoelastic effects. In addition, the measurement error and the detectable depth resolution of the dv/v are also addressed in this study. Finally, we suggest the high-resolution technique as a complementary means to be used for operational rock slope damage surveillance in the future.
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Yan, B., Ji, Y., & Shi, P. (2023). Frequency-dependent inversion based on spherical-wave reflection coefficient in elastic medium: Theory and methodology. Journal Of Applied Geophysics, 209.
Résumé: Plane-wave theory based on the Zoeppritz's equations and its various approximations have been extensively utilized in seismic processing and interpretation. However, localized sources used in field acquisition usually generate spherical wave. As a zero-order approximation of spherical reflected wave, plane reflected wave varies with seismic offset, which can only use amplitude information of multiple pre-critical offsets to estimate elastic parameters. While, the change of spherical wavefront curvature across reflected interfaces causes the amplitude and phase of spherical reflected wave to vary with seismic frequency and offset. Therefore, in addition to conducting conventional amplitude variation versus with offset inversion using a single frequency of multiple offsets, spherical reflected wave makes frequency-dependent inversion using multiple low frequencies of a single offset possible. Herein, we derive the integral expression of spherical wave reflection coefficient from the general solution of wave equation and verify the consistency of displacements of reflected wave simulated by numerical integral and finite difference method in elastic medium. Subsequently, we analyze and investigate the feasibility of frequency-dependent inversion using spherical wave reflection coefficient of a single offset in synthetic data with a planar reflection interface. Combining a global optimal algorithm, low frequency-dependent inversion based on spherical wave reflection coefficient can offer accurate velocity and density parameters for further seismic interpretation.
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Yang, Y. - H., Li, X., Hu, J. - C., Song, J., Zhao, J., Yassaghi, A., et al. (2023). The 2022 Hormozgan Doublet Earthquake: Two Blind Thrusts-Related Folding in Zagros Fold-And-Thrust Belt, Southeast Iran. Geophysical Research Letters, 50(4).
Résumé: A doublet earthquake event including two main shocks with a magnitude larger than M-w 6.0 occurred on 1 July 2022 in the Zagros fold-and-thrust belt, southeast Iran. The coseismic InSAR deformation field shows that this event caused significant surface uplift due to fault-related folding in the seismic zone. The estimated preferred faulting model suggests that a higher dip angle fault (maximum slip of similar to 1.1 m), and an overlying gentle dipping fault (maximum slip of similar to 1.2 m) within the Bandar-e-Lengeh Anticline, are responsible for the first and second main shocks, respectively. The calculated Coulomb failure stress change suggests that the first main shock and its M-w 5.7 aftershock have a significantly positive triggering effect in the second main shock. The accumulated interseismic strain should have been partly released by the two main shocks. Finally, the salt diapir activity may affect the generation of the earthquake in the seismic zone.
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Yates, A., Caudron, C., Lesage, P., Mordret, A., Lecocq, T., & Soubestre, J. (2023). Assessing similarity in continuous seismic cross-correlation functions using hierarchical clustering: application to Ruapehu and Piton de la Fournaise volcanoes. Geophysical Journal International, 233(1), 472–489.
Résumé: Passive seismic interferometry has become a popular technique towards monitoring. The method depends on the relative stability of background seismic sources in order to make repeatable measurements of subsurface properties. Such stability is typically assessed by examining the similarity of cross-correlation functions through time. Thus, techniques that can better assess the temporal similarity of cross-correlation functions may aid in discriminating between real subsurface processes and artificial changes related variable seismic sources. In this study, we apply agglomerative hierarchical clustering to cross-correlation functions computed using seismic networks at two volcanoes. This allows us to form groups of data that share similar characteristics and also, unlike common similarity measures, does not require a defined reference period. At Piton de la Fournaise (La Reunion island), we resolve distinct clusters that relate both to changes in the seismic source (volcanic tremor onset) and changes in the medium following volcanic eruptions. At Mt Ruapehu (New Zealand), we observe a consistency to cross-correlation functions computed in the frequency band of volcanic tremor, suggesting tremor could be useful as a repeatable seismic source. Our results demonstrate the potential of hierarchical clustering as a similarity measure for cross-correlation functions, suggesting it could be a useful step towards recognizing structure in seismic interferometry data sets. This can benefit both decisions in processing and interpretations of observed subsurface changes.
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Ying, C., Liu, C., Zhang, F., Zheng, L., Wang, X., Yin, H., et al. (2023). Solutions for an efficient arsenite oxidation and removal from groundwater containing ferrous iron. Water Research, 243.
Résumé: Manganese (Mn) oxides are extensively used to oxidize As(III) present in ground, drinking, and waste waters to the less toxic and more easily removable As(V). The common presence of multiple other cations in natural waters, and more especially of redox-sensitive ones such as Fe2+, may however significantly hamper As(III) oxidation and its subsequent removal. The present work investigates experimentally the influence of Mn(III) chelating agents on As(III) oxidation process in such environmentally relevant complex systems. Specifically, the influence of sodium pyrophosphate (PP), an efficient Mn(III) chelating agent, on As(III) oxidation by birnessite in the presence of Fe(II) was investigated using batch experiments at circum-neutral pH. In the absence of PP, competitive oxidation of Fe(II) and As(III) leads to Mn oxide surface passivation by Fe(III) and Mn(II/III) (oxyhydr)oxides, thus inhibiting As(III) oxidation. Addition of PP to the system highly enhances As(III) oxidation by birnessite even in the presence of Fe(II). PP presence prevents passivation of Mn oxide surfaces keeping As and Fe species in solution while lower valence Mn species are released to solution. In addition, reactive oxygen species (ROS), tentatively identified as hydroxyl radicals (& BULL;OH), are generated under aerobic conditions through oxygen activation by Fe(II)-PP complexes, enhancing As(III) oxidation further. The positive influence of Mn(III) chelating agents on As(III) oxidation most likely not only depend on their affinity for Mn(III) but also on their ability to promote formation of these active radical species. Finally, removal of As(V) through sorption to Fe (oxyhydr)oxides is efficient even in the presence of significant concentrations of PP, and addition of such Mn(III) chelating agents thus appears as an efficient way to enhance the oxidizing activity of birnessite in large-scale treatment for arsenic detoxification of groundwaters.
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Yokoo, S., Edmund, E., Morard, G., Baron, M. A., Boccato, S., Decremps, F., et al. (2023). Composition-dependent thermal equation of state of B2 Fe-Si alloys at high pressure. American Mineralogist, 108(3), 536–542.
Résumé: Solid iron-silicon alloys play an important role in planetary cores, especially for planets that formed under reducing conditions, such as Mercury. The CsCl (B2) structure occupies a considerable portion of the Fe-Si binary phase diagram at pressure and temperature conditions relevant for the core of Mercury, yet its thermodynamic and thermoelastic properties are poorly known. Here, we report in situ X-ray difraction measurements on iron-silicon alloys with 7-30 wt% Si performed in laser-heated diamond-anvil cells up to similar to 120 GPa and similar to 3000 K. Unit-cell volumes of the B2 phase at high pressures and high temperatures have been used to obtain a composition-dependent thermal equation of state of this phase. In turn, the thermal equation of state is exploited to determine the composition of the B2 phase in hcp+B2 mixtures at 30-100 GPa and to place constraints on the hcp+B2/B2 phase boundary, determined to vary between similar to 13-18 wt% Si in the considered pressure and temperature range. The hcp+B2/B2 boundary of Fe-Si alloys is observed to be dependent on pressure but weakly dependent on temperature. Our results, coupled with literature data on liquid equations of state, yield an estimation of the density contrast between B2 solid and liquid under Mercury's core conditions, which directly relates to the buoyancy of the crystallizing material. While the density contrast may be large enough to form a solid inner core by the gravitational sinking of B2 alloys in a Si-rich core, the density of the B2 solid is close to that of the liquid at solidus conditions for Si concentration approaching similar to 10 wt% Si.
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Yong, P., Brossier, R., Metivier, L., & Virieux, J. (2023). Localized adaptive waveform inversion: regularizations for Gabor deconvolution and 3-D field data application. Geophysical Journal International, 235(1), 448–467.
Résumé: Recently, we have developed a localized adaptive waveform inversion (LAWI) method to tackle the cycle-skipping issue in velocity reconstruction through seismic waveform inversion. The LAWI method employs a local matching filter, computed using Gabor deconvolution, to measure the instantaneous time-shift between observed and calculated data. Unlike the adaptive waveform inversion (AWI) approach, the LAWI method can take the non-stationarity between observed and calculated data into account. In this work, we investigate two types of regularization based on prior information about the expected filter, which could be a minimum-norm filter or a delta-shape filter, with regard to their effects on the robustness and resolution of inversion. We demonstrate on synthetic data the advantages and disadvantages of these two types of prior information, where the delta-type LAWI may handle multiple observed phases not initially predicted by the starting velocity model. Therefore, we apply the delta-type LAWI to a high-quality 3-D field data set in the North Sea, eliminating the need for data-windowing tuning, which can be tedious and time-consuming for 3-D data. Under different workflows with varying reliable initial models and frequency bands of the pressure data considered, we show that the LAWI approach is robust, effective and efficient for reconstructing the P-wave velocity, while other approaches such as AWI and graph-space optimal-transport method may require meticulous data-tuning strategies to converge to the correct model. Well logs and data fits, primarily from early arrivals, give us confidence that this LAWI approach could be applied to various acquisitions and subsurface targets, thanks to its phase-driven principle.
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Yong, P., Brossier, R., Metivier, L., & Virieux, J. (2023). Localized adaptive waveform inversion: theory and numerical verification. Geophysical Journal International, 233(2), 1055–1080.
Résumé: Correctly interpreting phase events thanks to data processing techniques based on correlation or deconvolution has been the focus of numerous studies in the field of high-resolution seismic imaging using full-waveform inversion. To mitigate the non-convexity of the misfit function and the risk to converge towards non-informative local minima, correlation and deconvolution techniques make it possible to focus on phase information instead of amplitude information and to design more convex misfit function, alleviating the dependency of the full-waveform inversion process on the accuracy of initial models. Such techniques however rely on the assumption that phase events can be compared one by one, or that all the phase events are shifted in time in a similar way. This assumption is not satisfied in practice, which limits the effectiveness of these correlation/deconvolution-based methods. To overcome this issue, we propose to account for the non-stationary relation between observed and predicted data through a local in-time deconvolution technique, based on time-frequency analysis of the signal using a Gabor transform. This makes it possible to estimate instantaneous time-shift between locally coherent phase events. This strategy generalizes the conventional normalized deconvolution technique, which has been popularized under the name of adaptive waveform inversion. To support the introduction of our novel method, we compare it with four misfit functions based respectively on classical cross-correlation, penalized cross-correlation, penalized deconvolution, and adaptive waveform inversion. We analyse the behaviour of these methods on specific scenarios, and then propose a comparison on 2-D synthetic benchmarks. We show how our 'localized' adaptive waveform inversion applies in these realistic tests and overcomes some of the limitations of the aforementioned techniques.
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Younes, N., Wautier, A., Wan, R., Millet, O., Nicot, F., & Bouchard, R. (2023). DEM-LBM coupling for partially saturated granular assemblies. Computers And Geotechnics, 162.
Résumé: In this paper, we propose a phase-field-based Lattice Boltzmann Method (LBM) model coupled with the Discrete Element Method (DEM) for simulating unsaturated granular media over a large range of degrees of saturation. The formation of capillary bridges between grains is computed via an LBM scheme that solves Navier-Stokes and Allen-Cahn equations for multi-phase flow in complex geometries. As for the motions of the grains, these are computed within DEM where the contact behavior between spherical particles is based on a simple elastic- plastic contact law. Using an efficient DEM-LBM coupling framework, capillarity effects are explored at the pore scale with the collapse of a sandcastle as a classic illustration. This is done by considering an assembly of several thousands of spherical particles connected by capillary bridges for different degrees of saturation. It is shown that the mean capillary stress increases with the degree of saturation up to a certain threshold beyond which capillary stress drops until complete saturation. In addition, the Soil Water Characteristic Curve is qualitatively recovered and compared to a theoretical model. As such, the proposed DEM-LBM coupling scheme becomes a viable numerical tool that can explicitly model and explore pore-scale phenomena in unsaturated soils.
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Zareeipolgardani, B., Piednoir, A., Joyard-Pitiot, B., Depres, G., Charlet, L., & Colombani, J. (2023). Multiscale investigation of the fate of silver during printed paper electronics recycling. Composite Interfaces, 30(6), 671–684.
Résumé: The use of printed paper electronics in consumer goods is expected to experience a mass development in the next future. The ink used in these devices contains silver nanomaterials that may be released into the environment at the product end-of-life. We report here the first evaluation of the fate of silver during a pilot-scale recycling of printed paper electronics, made of paper printed with a cellulose nanofibrils-silver nanowire ink. We show that the released effluents are mainly free from silver, which is retained in the pulp conserved for recycling. We use atomic force microscopy experiments to show that this strong pulp-silver bond is due to the embedding of the silver nanowires in the pulp by coils of cellulose nanofibrils. We propose an estimate of the resulting adhesion stress of the nanowires to the ink, high enough to keep the silver inside the pulp during the recycling procedure.
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Zeinalova, N., Ismail-Zadeh, A., Tsepelev, I., Melnik, O., & Schilling, F. (2023). Numerical thermomechanical modelling of lava dome growth during the 2007-2009 dome-building eruption at Volcán de Colima. Geophysical Journal International, 236(1), 290–304.
Résumé: Lava domes form during effusive eruptions due to an extrusion of highly viscous magmas from volcanic vents. In this paper we present a numerical study of the lava dome growth at Volcan de Colima, Mexico during 2007-2009. The mathematical model treats the lava dome extrusion dynamics as a thermomechanical problem. The equations of motion, continuity and heat transfer are solved with the relevant boundary and initial conditions in the assumption that magma viscosity depends on the volume fraction of crystals and temperature. We perform several sets of numerical experiments to analyse the internal structure of the lava dome (i.e. the distributions of the temperature, crystal content, viscosity and velocity) depending on various heat sources and thermal boundary conditions. Although the lava dome growth at Volcan de Colima during short (a few months) dome-building episodes can be explained by an isothermal model of lava extrusion with the viscosity depending on the volume fraction of crystals, we show here that cooling plays a significant role during long (up to several years) episodes of dome building. A carapace develops as a response to a convective cooling at the lava dome-air interface. The carapace becomes thicker if the radiative heat loss at the interface is also considered. The thick carapace influences the lava dome dynamics preventing its lateral advancement. The release of the latent heat of crystallization leads to an increase of the temperatures in the lava dome interior and to a relative flattening of the dome. Meanwhile, the heat source due to viscous dissipation inside the lava dome is negligible, and it does not influence the lava dome growth. The developed thermomechanical model of the lava dome dynamics at Volcan de Colima can be used elsewhere to analyse effusive eruptions, dome morphology and carapace evolution including its failure potentially leading to pyroclastic flow hazards.
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Zerathe, S., Audin, L., Robert, X., Schwartz, S., & Carcaillet, J. (2023). Large landslide of the hyperarid Central Western Andes triggered during a humid period of the Late Pleistocene (ca. 19°S; northern Chile). Terra Nova, 35(3), 174–184.
Résumé: The western flank of the Central Andes offers a unique geomorphological record of large paleolandslides that are well preserved on long time-scales (i.e. >= Pleistocene) due to the long-lasting aridity of this region. However, the lack of chronological constraints on those landslides limits our understanding of the respective role of tectonics and climate on their triggering. Here, we report new Be-10 surface exposure dating obtained on one of those giant slope-failures: the Limaxina landslide (northern Chile, 19 degrees S). Five tightly grouped exposure-ages (one outlier discarded) point to a single landslide failure at 80 +/- 4 ka. This timing being consistent with others local records of a wet episode in the Atacama Desert, it suggests a primary role of climate-forcing on landslide activity in this region, calling to further slope failures dating in the arid Central western Andes to explore landscapes responses to Quaternary climate oscillations and extreme events.
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Zhang, P., Cheng, P., Zhang, J., Liu, G., Weiss, J., & Sun, J. (2023). Coupled size and temperature effects on intermittent plasticity of BCC micro-crystals. Acta Materialia, 260.
Résumé: The intermittent plasticity of pure Mo microcrystals with diameters from 500 to 3500 nm was studied using micro-pillar compression methodology at temperatures ranging from 25 degrees C to 200 degrees C, in order to explore its dependence on external size and temperature. The technological background is the potential value of BCC metals in the manufacture of high-temperature components in modern fields requiring miniaturization, such as microelectronics. We analyzed plastic fluctuations in terms of wildness, avalanche size distribution, and burst peak velocity. This reveals coupled size and temperature effects on a mild-to-wild transition: the transition temperature decreases with decreasing sample diameter, while the transition diameter increases with rising temperature. In addition, strain-rate sensitivity tests were conducted, implying that mild plasticity is associated to screw dislocation motions controlled by thermally activated nucleation of kink-pairs, whereas wild plasticity is nearly athermal. This experimental observation is interpreted by a damping effect of the thermally activated motion of screw dislocations on the propagation of avalanches. From this, we propose a controlling parameter based on a simple dislocation source model, which unifies the coupled sample size and temperature effects on the mild-to-wild transition, and which could be of practical significance for microscale applications.
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Zhang, R., Boue, P., Campillo, M., & Ma, J. (2023). Quantifying P-wave secondary microseisms events: a comparison of observed and modelled backprojection. Geophysical Journal International, 234(2), 933–947.
Résumé: Secondary microseisms are caused by nonlinear interactions between ocean waves of approximately equal wavelengths and opposite propagation directions. This seismic forcing is evaluated using ocean sea-state hindcast data and further modulated by the bathymetric effect. The numerical ocean model provides a global activity representation of the secondary microseisms, from which we isolate major events. We backprojected teleseismic P-wave propagation into the Earth's mantle to validate these events as effective seismic sources. The ocean model provides spectral amplitude information for modelling microseisms generated seismic wavefield. A comparison of the backprojection for P and PP phases from observed and synthetic microseisms forcing indicates high reliability in the ocean model, at least for major sources. A combination of P and PP phases detected across a global network of stations enables global ocean coverage. We improve backprojection images even further by introducing a two-step stacking for the P phase to address the problem of unbalanced station distribution. Thresholds of microseisms events forces valuable for seismic imaging are determined by comparing backprojections and ocean models for the years 2015 and 2020. Finally, we extracted a catalogue of microseisms events every 3-hr from 1994 to 2020 from the ocean hindcast data set. This catalogue is an intriguing resource for future applications of interferometric imaging at large scale.
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Zhang, X.(Y.), Bajard, M., Bouchez, J., Sabatier, P., Poulenard, J., Arnaud, F., et al. (2023). Evolution of the alpine Critical Zone since the Last Glacial Period using Li isotopes from lake sediments. Earth And Planetary Science Letters, 624.
Résumé: Comprehending and predicting the way humans affect the Earth's Critical Zone remains a challenge. An un-derstanding of the past changes resulting from human and non-human influences in the dynamics of the Critical Zone is crucial. Here, we use a retrospective approach to address this question based on a new lithium (Li) isotope record from the Late Glacial Period to the present from a pre-Alpine lake sediment sequence (Lake La Thuile, France). Coupled with the lake sediment archive, the investigation of present-day soils in the lake catchment suggests that lake sediments are not necessarily recording the erosoin of topsoil in the catchment. Our findings indicate that soil particles can be sorted during transportation to the lake, with finer particles being preferentially mobilized, highlighting the influence of fine particle transport on the Li isotope signature of soils and lake sediments. Characterized by low Li isotope signatures, changes in weathering signatures in lake sedi-ments can be amplified by the combined effect of soil development and selective transport. In the La Thuile catchment, soil development was limited during the Late Glacial Period, whereas it became a dominant process during the Holocene climatic optimum together with enhanced selective transport of fine particles. Human ac-tivities since 3,000-4,000 yr cal BP induced a strong perturbation hindering both soil formation and selective transport by reinforcing erosion rates. After a period of topsoil destruction caused by intense deforestation and agriculture, lake Li isotopes record the evolution of soil profiles associated with changes in agricultural practices.
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Zhao, B., Morard, G., Boulard, E., Boccato, S., Siersch, N. C. C., Rivoldini, A., et al. (2023). Local Structure and Density of Liquid Fe-C-S Alloys at Moon's Core Conditions. Journal Of Geophysical Research-Planets, 128(3).
Résumé: The local structure and density of ternary Fe-C-S liquid alloys have been studied using a combination of in situ X-ray diffraction and absorption experiments between 1 and 5 GPa and 1600-1900 K. The addition of up to 12 at% of carbon (C) to Fe-S liquid alloys does not significantly modify the structure, which is largely controlled by the perturbation to the Fe-Fe network induced by S atoms. The liquid density determined from diffraction and/or absorption techniques allows us to build a non-ideal ternary mixing model as a function of pressure, temperature, and composition in terms of the content of alloying light elements. The composition of the Moon's core is addressed based on this thermodynamic model. Under the assumption of a homogeneous liquid core proposed by two recent Moon models, the sulfur content would be 27-36 wt% or 12-23 wt%, respectively, while the carbon content is mainly limited by the Fe-C-S miscibility gap, with an upper bound of 4.3 wt%. On the other hand, if the core is partially molten, the core temperature is necessarily lower than 1850 K estimated in the text, and the composition of both the inner and outer core would be controlled by aspects of the Fe-C-S phase diagram not yet sufficiently constrained.
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Zhao, P., Campillo, M., Chen, J., Liu, Q., Li, S., & Li, Y. (2023). Upper to middle crustal structure beneath the Longmen Shan fault zone: Implications for the growth of eastern Tibet. Journal Of Asian Earth Sciences, 245.
Résumé: The Longmen Shan (LMS) fault zone is located on the eastern margin of the Tibetan Plateau and is a repre-sentative area for studying the eastward growth of the plateau. In this study, we present a 3-D crustal S-wave velocity structure beneath the LMS fault zone and its adjacent regions with a lateral resolution of similar to 10 km down to a depth of 25 km from data recorded at 57 stations over one year using seismic ambient noise imaging techniques. The high and steep topography of the LMS is considered when building the high-resolution image of the upper and middle crust. The imaging provides further evidence for the high-angle listric characteristics of the LMS faults south of Beichuan, and the feature disappears toward the north, indicating differences in deformation from south to north. The structural characteristics are well correlated with the aftershock distribution and the rupture of the Wenchuan earthquake, which indicate a change in the mechanism from mostly thrust in the south to mostly strike slip in the north. The velocity structure controls the downward stretch of the faults. The results support that crustal channel flow is responsible for the growth of eastern Tibet. The eastward movement of the weak crustal material was blocked by the hard crust surrounding the Minshan uplift, resulting in great differ-ences in the velocity structures and fault properties south and north of Beichuan.
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Ziegler Rivera, F. R. A., Pano, B. P., Guedron, S., Palomino, L. M., Hill, C. P. de L., & Grabach, C. S. (2023). Impact of the change in irrigation practices from untreated to treated wastewater on the mobility of potentially toxic elements (PTEs) in soil irrigated for decades. Journal Of Soils And Sediments, 23(7), 2726–2743.
Résumé: PurposeLong-term agricultural irrigation with untreated wastewater has resulted in metals and metalloids accumulation in soil. Little information is available on the consequences of a change to irrigation with treated water on the mobility of these potentially toxic elements (PTEs).Materials and methodsThe potential mobility of PTEs was assessed using sequential extractions performed on soil irrigated with untreated wastewater for a century in Mexico. The possible effects of change in irrigation practices on PTEs mobility was evaluated through batch experiments, simulating a decrease in pH, an increase in salinity, and in chlorine of the irrigation water. Geochemical modeling allowed predicting the speciation of mobilized PTEs.Results and discussionSoils irrigated with untreated water were mainly enriched with PTEs in surface horizons. Only Cd and As were found in the soluble or exchangeable fractions (< 20%). Cu and Pb were mainly associated with soil organic matter (OM), whereas As and Zn were bound to iron oxides, and Cr with refractory minerals. Batch experiments revealed that acidification resulted in the increased solubility of Cu, Zn, and Cd for surface samples, and As in deep horizons. In contrast, increased salinity only mobilized Zn, Cd, and Cr. Water chlorination mobilized higher amount of Zn, Pb, and Cd compared to the other experiments. As was not mobilized for these two experiments.ConclusionA change in irrigation practices could increase the mobility of PTEs if water treatment is not adapted to the soil type. The mobilization of PTEs, especially As and Cd, could affect both crops and groundwater quality. It is essential to monitor this mobility to avoid future risks to human health.
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