2022 |
Aden-Antoniow, F., Frank, W. B., & Seydoux, L. (2022). An Adaptable Random Forest Model for the Declustering of Earthquake Catalogs. Journal Of Geophysical Research-Solid Earth, 127(2).
Résumé: Earthquake catalogs are essential to analyze the evolution of active fault systems. The background seismicity rate, or rate of earthquakes that are not directly triggered by other earthquakes, directly relates to the stressing rate, a crucial quantity for understanding the seismic hazards. Determining the background seismicity rate is challenging because aftershock sequences may dominate the seismicity rate. Classifying these events in earthquake catalogs-known as catalog declustering-is a common practice and most declustering solutions rely on spatiotemporal distances between events, such as the nearest-neighbor-distance algorithm, widely used in various contexts. This algorithm assumes that the nearest-neighbor distance (NND) follows a bimodal distribution related to the background seismicity and to the aftershocks. Constraining these two distributions is crucial to distinguish the aftershocks from the background events accurately. Recent work often uses linear splitting based on the NND, ignoring the potential overlap between the two populations and resulting in a biased identification of background earthquakes and aftershock sequences. We revisit this problem with machine-learning algorithms. After testing several popular algorithms, we show that a random forest trained with various synthetic catalogs generated by an Epidemic-Type Aftershock Sequence model outperforms approaches such as k-means, Gaussian-mixture models, and support vector machine classification. We apply our model to two different earthquake catalogs: the relocated Southern California earthquake center catalog and the GeoNet catalog of New Zealand. Our model capably adapts to these two different tectonic contexts, highlighting the differences in aftershock productivity between crustal and intermediate-depth seismicity.
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Aiken, J. M., Sohn, R. A., Renard, F., Matter, J., Kelemen, P., & Jamtveit, B. (2022). Gas Migration Episodes Observed During Peridotite Alteration in the Samail Ophiolite, Oman. Geophysical Research Letters, 49(21).
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Albino, F., Biggs, J., Lazecky, M., & Maghsoudi, Y. (2022). Routine Processing and Automatic Detection of Volcanic Ground Deformation Using Sentinel-1 InSAR Data: Insights from African Volcanoes. Remote Sensing, 14(22).
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Alboussiere, T., Plunian, F., & Moulin, M. (2022). Fury: an experimental dynamo with anisotropic electrical conductivity. Proceedings Of The Royal Society A-Mathematical Physical And Engineering Sciences, 478(2268).
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Andrault, D., Pison, L., Morard, G., Garbarino, G., Mezouar, M., Bouhifd, M. A., et al. (2022). Comment on: Melting behavior of SiO2 up to 120 GPa (Andrault et al. 2020). Physics And Chemistry Of Minerals, 49(2).
Résumé: The additional work we have done using our new laser heating in the diamond anvil cell system since the publication of Andrault et al. (Phys Chem Mineral 47(2), 2020) leads us to the conclusion that there was a systematic bias in the determination of temperature. First, the temperature of the W-lamp used for the calibration of the optical system was overestimated by similar to 22 K at 2273 K. Then, we made the assumption that hot SiO2 was a grey-body (constant emissivity epsilon(lambda)), while the available measurements suggest instead that epsilon(lambda) of SiO2 is similar to that of tungsten. Applying these two corrections lowers the SiO2 melting temperatures significantly. In LMV, we performed a new experimental determination of the SiO2 melting temperature, at 5000 (200) K and similar to 70 (4) GPa, which is well compatible with the amplitude of the correction proposed. The reevaluation of the melting temperature profile does not affect largely the interpretations or the main conclusions presented in Andrault et al. (Phys Chem Mineral 47(2), 2020). Within the stability field of stishovite, the melting curve still presents a relatively sharp change of slope at P-T recalculated as similar to 40 GPa and similar to 4800 K. It is related to a change of the melt structure. At higher pressures, the melting curve is almost flat up to the subsolidus transition from stishovite to the CaCl2-form around 85 GPa, where the slope of the melting curve increases again up to similar to 120 GPa. We present corrected figures and tables of the original publication.
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Andrieu, B., Vidal, O., Le Boulzec, H., Delannoy, L., & Verzier, F. (2022). Energy Intensity of Final Consumption: the Richer, the Poorer the Efficiency. Environmental Science & Technology, 56(19), 13909–13919.
Résumé: ABSTRACT: To maintain perpetual economic growth, most energy transition scenarios bet on a break in the historical relationship between energy use and gross domestic product (GDP). Practical limits to energy efficiency are overlooked by such scenarios, in particular the fact that high-income individuals tend to buy goods and services that are more energy intensive. Detailed assessments of the energy embodied in regional final consumption are needed to better understand the relationship between energy and GDP. Here, we calculate the energy necessary to produce households and governments??? final consumption in 49 world regions in 2017. We correct prices at the sector level and account for the energy embodied in the whole value chain, including capital goods. We find that high-income regions use more energy per unit of final consumption than low-income ones. This result contradicts the common belief that a higher GDP is correlated with a better efficiency and questions the feasibility of mainstream energy transition scenarios based on universal GDP growth.
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Anselmetti, F. S., Bavec, M., Crouzet, C., Fiebig, M., Gabriel, G., Preusser, F., et al. (2022). Drilling Overdeepened Alpine Valleys (ICDP-DOVE): quantifying the age, extent, and environmental impact of Alpine glaciations. Scientific Drilling, 31, 51–70.
Résumé: The sedimentary infill of glacially overdeepened valleys (i.e., structures eroded below the fluvial base level) is an excellent but yet underexplored archive with regard to the age, extent, and nature of past glaciations. The ICDP project DOVE (Drilling Overdeepened Alpine Valleys) Phase 1 investigates a series of drill cores from glacially overdeepened troughs at several locations along the northern front of the Alps. All sites will be investigated with regard to several aspects of environmental dynamics during the Quaternary, with focus on the glaciation, vegetation, and landscape history. Geophysical methods (e.g., seismic surveys), for example, will explore the geometry of overdeepened structures to better understand the process of overdeepening. Sedimentological analyses combined with downhole logging, analysis of biological remains, and state-of-the-art geochronological methods, will enable us to reconstruct the erosion and sedimentation history of the overdeepened troughs. This approach is expected to yield significant novel data quantifying the extent and timing of Middle and Late Pleistocene glaciations of the Alps. In a first phase, two sites were drilled in late 2021 into filled overdeepenings below the paleolobe of the Rhine Glacier, and both recovered a trough filling composed of multiphase glacial sequences. Fully cored Hole 50681C reached a depth of 165m and recovered 10m molasse bedrock at the base. This hole will be used together with two flush holes (50681A, 50681B) for further geophysical cross-well experiments. Site 50682 reached a depth of 255m and bottomed out near the soft rock-bedrock contact. These two sites are complemented by three legacy drill sites that previously recovered filled overdeepenings below the more eastern Alpine Isar-Loisach, Salzach, and Traun paleoglacier lobes (50683, 50684, 50685). All analysis and interpretations of this DOVE Phase 1 will eventually lay the ground for an upcoming Phase 2 that will complete the pan-Alpine approach. This follow-up phase will investigate overdeepenings formerly occupied by paleoglacier lobes from the western and southern Alpine margins through drilling sites in France, Italy, and Slovenia. Available geological information and infrastructure make the Alps an ideal area to study overdeepened structures; however, the expected results of this study will not be restricted to the Alps. Such features are also known from other formerly glaciated mountain ranges, which are less studied than the Alps and more problematic with regards to drilling logistics. The results of this study will serve as textbook concepts to understand a full range of geological processes relevant to formerly glaciated areas all over our planet.
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Aribowo, S., Husson, L., Natawidjaja, D. H., Authemayou, C., Daryono, M. R., Puji, A. R., et al. (2022). Active Back-Arc Thrust in North West Java, Indonesia. Tectonics, 41(7).
Résumé: The Java Back-arc Thrust scars the entire back-arc area of Java Island, but the faults' nature, timing, and activity remain partly elusive. Characterizing the structure and activity of the seismogenic Java Back-arc Thrust (historical earthquakes up to 7 M-w) is a cornerstone to evaluate associated geohazards. We focus on the western part of Java Back-arc Thrust that reaches the megalopolis of Jakarta. We combine morphotectonic data, seismic reflection, electric resistivity profiles, kinematic, structural field measurements, paleoseismological trenching, and sediment dating (optically stimulated luminescence and C-14). Our results suggest that the interplay between the faults, volcanoes, and sedimentary basin modulates the propagation of the fault system across and along-strike. The West Java Back-arc Thrust has been active from Pliocene to Recent, but with a laterally variable tempo and tectonic regime. While tectonic activity was sustained for longer times in the eastern part, the West Java Back-arc Thrust broke through the Jakarta Basin in the west, possibly only since the Late Pleistocene, and partitions into a network of immature transpressive structures. We conclude that the West Java Back-arc Thrust has a high seismic hazard that requires a careful risk evaluation along its trace, as it threatens the numerous infrastructures of the densely populated West Java.
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Aristizabal, C., Bard, P. Y., & Beauval, C. (2022). Site-Specific PSHA: Combined Effects of Single-Station-Sigma, Host-to-Target Adjustments and Nonlinear Behavior. A case study at Euroseistest. Italian Journal Of Geosciences, 141(1), 5–34.
Résumé: This study takes advantage of the available information for an example, well-known, site in Greece (TST site at Euroseistest) to illustrate the epistemic variability in probabilistic seismic hazard assessment (PSHA) estimates. The purpose is not to perform an exhaustive site-specific PSHA at this particular site, but to investigate the sensitivity of the results to the approach used for including site effects, from basic ones to more demanding and realistic ones, in order to better appreciate the “benefits” versus the required costs and efforts of each approach. The TST site, located at the center of the Mygdonian basin in North-Eastern Greece is characterised by soft shallow soils over thick, medium stiffness deposits with a complex underground geometry, resting on very hard bedrock. Three different levels are considered for the incorporation of site response, from level 0 (generic or partially generic) to site-specific ones, with linear (level 1) or non-linear (level 2) site response analysis. The basic methods rely on one or several site proxies (V-S30, V-SZ and f(0)), whereas the most complex ones couple site response assessment (instrumental or numerical, implying site-specific characterization or instrumentation) with various reference rock hazard adjustments (single-station sigma, host-to-target adjustments, depth correction). Results are compared in terms of Uniform Hazard Spectra for a 5000 years return period, a typical value for critical facilities. For each level, the epistemic uncertainties are described and their impacts on hazard estimates are quantified. The use of the V-S30 proxy in ground-motion prediction equations (GMPEs) leads to a clear underestimation of the hazard for the linear case (i.e., short return periods), especially around the site fundamental period, because of resonance and basin effects. On the other hand, soil nonlinearity largely impacts the hazard estimates, and linear amplification approach leads to an overestimation of the hazard, with unrealistic high levels at very long return periods. Sitespecific hazard estimates for thick, Euroseistest-like sites, with complex geometry and rheology, are thus shown to come up against several additional epistemic uncertainties implying a large approach-to-approach variability. This may lead to increased hazard estimates, counterbalancing the decrease due to the use of reduced, single-site aleatory uncertainty in reference rock hazard estimates. For the time being, it thus looks unrealistic to promise a systematic reduction in hazard estimates with site-specific studies, while it might also indicate that uncertainties in generic hazard estimates could presently be underestimated.
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Arndt, N., Cordier, C., Boullier, A. - M., Batanova, V., Magnin, V., & Findling, N. (2022). Olivine in Kimberlites and Related Rocks – Macrocrysts, Dunitic Nodules and Megacrysts from the Same Metasomatized Source. Journal Of Petrology, 63(8).
Résumé: Kimberlites carry a dense cargo of olivine. Although normally referred to as macrocrysts, much of this olivine is present as multigrain xenoliths of dunite. Because of their well-rounded outlines, we refer to these objects as 'nodules' and apply the term to both multigranular and monogranular varieties. Although compositions within each nodule are very uniform, the entire population displays an enormous variation in Fo content (100*Mg/(Mg + Fe), cation proportions), from close to Fo95 to about Fo82. The change is continuous, and there is no indication of separate Fo-rich and Fo-poor populations. Likewise, the sizes, internal textures and habits of Fo-rich and Fo-poor olivines are indistinguishable. Fo-poor nodules have compositions like those of olivines of the megacryst suite, and they share similar sizes and internal structures. We propose that the dunite nodules in kimberlites and olivines of the megacryst suite have a common origin. In our interpretation, almost all olivines in kimberlites, except for the marginal rims and rinds, are fragments of dunite that was produced during interaction between mantle peridotite and CO2-rich fluid. Analogues of this process can be found in ophiolites where dunite is the product of reaction between basaltic magma and peridotite. In situ reactive crystallization eliminated pyroxene, leaving only olivine with Fo contents ranging from higher to lower Fo than in the host peridotite. This interaction occurred near the base of the lithosphere and not during transit of kimberlite towards the surface.
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Asten, M. W., Yong, A., Foti, S., Hayashi, K., Martin, A. J., Stephenson, W. J., et al. (2022). An assessment of uncertainties in V-S profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials. Journal Of Seismology, 26(4), 757–780.
Résumé: Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site conditions of the local geology. Thus, a number of geophysical site characterization methods were developed to meet the demand for accurate and cost-effective results. As a consequence, a number of studies have been administered periodically as blind trials to evaluate the state-of-practice on-site characterization. We present results from the Consortium of Organizations for Strong Motion Observation Systems (COSMOS) blind trials, which used data recorded from surface-based microtremor array methods (MAM) at four sites where geomorphic conditions vary from deep alluvial basins to an alpine valley. Thirty-four invited analysts participated. Data were incrementally released to 17 available analysts who participated in all four phases: (1) two-station arrays, (2) sparse triangular arrays, (3) complex nested triangular or circular arrays, and (4) all available geological control site information including drill hole data. Another set of 17 analysts provided results from two sites and two phases only. Although data from one site consisted of recordings from three-component sensors, the other three sites consisted of data recorded only by vertical-component sensors. The sites cover a range of noise source distributions, ranging from one site with a highly directional microtremor wave field to others with omni-directional (azimuthally distributed) wave fields. We review results from different processing techniques (e.g., beam-forming, spatial autocorrelation, cross-correlation, or seismic interferometry) applied by the analysts and compare the effectiveness between the differing wave field distributions. We define the M index as a quality index based on estimates of the time-averaged shear-wave velocity of the upper 10 (V-S10), 30 (V-S30), 100 (V-S100), and 300 (V-S300) meters and show its usefulness in quantitative comparisons of V-S profiles from multiple analysts. Our findings are expected to aid in building an evidence-based consensus on preferred cost-effective arrays and processing methodology for future studies of seismic site effects.
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Aubry, T. J., Farquharson, J. I., Rowell, C. R., Watt, S. F. L., Pinel, V., Beckett, F., et al. (2022). Impact of climate change on volcanic processes: current understanding and future challenges. Bulletin Of Volcanology, 84(6).
Résumé: The impacts of volcanic eruptions on climate are increasingly well understood, but the mirror question of how climate changes affect volcanic systems and processes, which we term “climate-volcano impacts”, remains understudied. Accelerating research on this topic is critical in view of rapid climate change driven by anthropogenic activities. Over the last two decades, we have improved our understanding of how mass distribution on the Earth's surface, in particular changes in ice and water distribution linked to glacial cycles, affects mantle melting, crustal magmatic processing and eruption rates. New hypotheses on the impacts of climate change on eruption processes have also emerged, including how eruption style and volcanic plume rise are affected by changing surface and atmospheric conditions, and how volcanic sulfate aerosol lifecycle, radiative forcing and climate impacts are modulated by background climate conditions. Future improvements in past climate reconstructions and current climate observations, volcanic eruption records and volcano monitoring, and numerical models all have a role in advancing our understanding of climate-volcano impacts. Important mechanisms remain to be explored, such as how changes in atmospheric circulation and precipitation will affect the volcanic ash life cycle. Fostering a holistic and interdisciplinary approach to climate-volcano impacts is critical to gain a full picture of how ongoing climate changes may affect the environmental and societal impacts of volcanic activity.
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Auclair, J. - P., Dumont, D., Lemieux, J. - F., & Ritchie, H. (2022). A model study of convergent dynamics in the marginal ice zone. Philosophical Transactions Of The Royal Society A-Mathematical Physical And Engineering Sciences, 380(2235).
Résumé: With the increasing resolution of operational forecasting models, the marginal ice zone (MIZ), the area where waves and sea ice interact, can now be better represented. However, the proper mechanics of wave propagation and attenuation in ice, and especially their influence on sea ice dynamics, still remain poorly understood and constrained in models. Observations have shown exponential wave energy decrease with distance in sea ice, particularly strong at higher frequencies. Some of this energy is transferred to the ice, breaking it into smaller floes and weakening it, as well as exerting a stress on the ice similar to winds and currents. In this article, we present a one-dimensional, fully integrated wave and ice model that has been developed to test different parameterizations of wave-ice interactions. The response of the ice cover to the wind and wave radiative stresses is investigated for a variety of wind, wave and ice conditions at different scales. Results of sensitivity analyses reveal the complex interplay between wave attenuation and rheological parameters and suggest that the compressive strength of the MIZ may be better represented by a Mohr-Coulomb parameterization with a nonlinear dependence on thickness.This article is part of the theme issue 'Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks'.
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Authemayou, C., Pedoja, K., Chauveau, D., Husson, L., Brocard, G., Delcaillau, B., et al. (2022). Deformation and uplift at the transition from oceanic to continental subduction, Sumba Island, Indonesia. Journal Of Asian Earth Sciences, 236.
Résumé: The transition along the strike of the Sunda subduction zone, from oceanic subduction in the west to subduction of continental Australian lithosphere in the east is envisioned as one of the canonical examples of the structural changes that take place within an overriding plate when a continental lithosphere wedge enters a subduction zone. Yet, the along-strike offset of the trench toward the Australian margin represents a structural response opposite to the predictions of numerical models. To understand this paradox, we analyse the morphotectonic evolution of Sumba island located at the transition from oceanic to continental Indo-Australian lithosphere subduction. Drainage evolution allows us to constrain the topographic evolution of the island since the Pliocene. Flights of uplifted coral reef terraces document Quaternary deformation. Focal mechanisms of shallow crustal earthquakes constrain the current stress field. Together, these data reveal that the island is affected by dextral en-e ' chelon folding. Offshore, west of the island, reverse and strike-slip focal mechanisms evidence an active dextral transpressional zone. The emergence of the island and dextral shearing of the accretionary prism were triggered by subduction of the western lateral boundary of the Australian continental margin. We contend that the Plio-Quaternary tectonic evolution of the region, with transpression and migration of the trench toward the Australian margin is primarily dictated by shear stress transfer from the lower plate to the overriding plate, favored by strong interplate coupling, and by southwestward escape of the Savu-Sumba block following the impingement of the Australian continental margin against Timor island.
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Bablon, M., Ratzov, G., Nauret, F., Samaniego, P., Michaud, F., Saillard, M., et al. (2022). Holocene Marine Tephra Offshore Ecuador and Southern Colombia: First Trench-to-Arc Correlations and Implication for Magnitude of Major Eruptions. Geochemistry Geophysics Geosystems, 23(9).
Résumé: Tephra layers preserved in marine sediments are strong tools to study the frequency, magnitude and source of past major explosive eruptions. Thirty-seven volcanoes from the Ecuadorian and Colombian arc, in the northern Andes, experienced at least one eruption during the Holocene. The volcanic hazard is therefore particularly high for the populated areas of the Andes and in particular cases for the coastal region, and it is crucial to document such events to improve hazard assessment. The age and distribution of deposits from major Holocene eruptions have been studied in the Cordillera, but no descriptions of distal fallouts have been published. In this study, we focused on 28 Holocene tephra layers recorded in marine sediment cores collected along the northern Ecuador-Southern Colombia margin. New lithological, geochemical and isotope data together with C-14 datings on foraminifers allow us to determine the age and volcanic source of marine tephra, and to propose a first land-sea correlation of distal tephra fallouts. We show that at least seven explosive eruptions from Guagua Pichincha, Atacazo-Ninahuilca, Cotopaxi, and Cerro Machin volcanoes left tephra deposits recorded in marine cores over 250 km away from their source. Volume estimates of emitted tephra range between 1.3 and 6.0 km(3) for the tenth century Guagua Pichincha, similar to 5 ka Atacazo-Ninahuilca, similar to 6.7 and similar to 7.9 ka Cotopaxi events, suggesting that they were eruptions of Volcanic Explosivity Index of 5. The distribution of these deposits also brings new constraints for a better evaluation of the volcanic hazard in Ecuador.
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Banjan, M., Christian, C., Pierre, S., Herve, J., Manon, B., Francois, D., et al. (2022). Did the Younger Dryas to Holocene climate transition favour high seismicity rates in the north-western Alps? Sedimentology, .
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., Margerin, L., & Campillo, M. (2022). Coupled body and surface wave sensitivity kernels for coda-wave interferometry in a three-dimensional scalar scattering medium. Geophysical Journal International, 230(2), 1013–1029.
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Baron, M. A., Fiquet, G., Morard, G., Miozzi, F., Esteve, I., Doisneau, B., et al. (2022). Melting of basaltic lithologies in the Earth's lower mantle. Physics Of The Earth And Planetary Interiors, 333.
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Bassal, F., Roques, J., Corre, M., Brunet, F., Ketcham, R., Schwartz, S., et al. (2022). Role of Defects and Radiation Damage on He Diffusion in Magnetite: Implication for (U-Th)/He Thermochronology. Minerals, 12(5).
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Beauce, E., van der Hilst, R. D., & Campillo, M. (2022). An Iterative Linear Method with Variable Shear Stress Magnitudes for Estimating the Stress Tensor from Earthquake Focal Mechanism Data: Method and Examples. Bulletin Of The Seismological Society Of America, 112(3), 1224–1239.
Résumé: Earthquake focal mechanism data provide information about the stress state at the origin of earthquakes. The inversion methods that are commonly used to infer the stress tensor from focal mechanisms have varying complexity but always rely on a number of assumptions. We present an iterative method built upon a classic linear stress tensor inversion that allows for relaxing the assumption on shear stress magnitudes while preserving the computational simplicity of the linear problem. Every iteration of our method computes the least-squares solution of the problem, which makes the method fast enough to estimate the inverted parameter errors with nonparametric resampling methods such as bootstrapping. Following previous studies, this method removes the fault plane ambiguity in focal mechanism data by selecting the nodal plane that best satisfies the Mohr???Coulomb failure criterion. We first test the performance and robustness to noise of the proposed method on synthetic data sets and then apply it to data from the Southern California and Geysers geothermal field data sets. We focus the study on investigating the consequences of relaxing the assumption of constant shear stress magnitudes. Our variable shear method successfully generalizes its constant shear counterpart: it is able to perform similarly when the constant shear assumption is a good approximation and provides more accurate results when it is not. We provide the Python package iterative linear stress inversion to implement the proposed method.
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Beauce, E., van der Hilst, R. D., & Campillo, M. (2022). Microseismic Constraints on the Mechanical State of the North Anatolian Fault Zone 13 Years After the 1999 M7.4 Izmit Earthquake. Journal Of Geophysical Research-Solid Earth, 127(9).
Résumé: The 17 August 1999 M(w)7.4 Izmit earthquake ruptured the western section of the North Anatolian Fault Zone and strongly altered the fault zone properties and stress field. Consequences of the co- and post-seismic stress changes were seen in the spatio-temporal evolution of the seismicity and in the surface slip rates. Thirteen years after the Izmit earthquake, in 2012, the seismic network Dense Array for North Anatolia (DANA) was deployed for 1.5 years. We built a new catalog of microseismicity (M < 2) by applying our automated detection and location method to the DANA data set. Our method combines a systematic backprojection of the seismic wavefield and template matching. We analyzed the statistical properties of the catalog by computing the Gutenberg-Richter b-value and by quantifying the amount of temporal clustering in groups of nearby earthquakes. We found that the microseismicity mainly occurs off the main fault and that the most active regions are the Lake Sapanca step-over and near the Akyazi fault. Based on previous studies, we interpreted the b-values and temporal clustering (a) as indicating that the Akyazi seismicity is occurring in high background stresses and is driven by the Izmit earthquake residual stresses, and (b) as suggesting evidence that an intricate combination of seismic and aseismic slip was taking place on heterogeneous faults at the eastern Lake Sapanca, near the brittle-ductile transition. Combined with geodetic evidence for enhanced north-south extension around Lake Sapanca following the Izmit earthquake, the seismicity supports the possibility of slow slip at depth in the step-over.
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Berent, K., Cartwright, J. H. E., Checa, A. G., Pimentel, C., Ramos-Silva, P., & Sainz-Diaz, C. I. (2022). Helical microstructures in molluscan biomineralization are a biological example of close packed helices that may form from a colloidal liquid crystal precursor in a twist-bend nematic phase. Physical Review Materials, 6(10).
Résumé: We demonstrate that nature has produced a close-packed helical twisted filamentous material in the biomineralization of the mollusk. In liquid crystals, twist-bend nematics have been predicted and observed. We present and analyze evidence that the helical biomineral microstructure of mollusk shells may be formed from such a liquid-crystal precursor.
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Berger, A., Egli, D., Glotzbach, C., Valla, P. G., Pettke, T., & Herwegh, M. (2022). Apatite low-temperature chronometry and microstructures across a hydrothermally active fault zone. Chemical Geology, 588.
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Bergfeld, B., van Herwijnen, A., Bobillier, G., Larose, E., Moreau, L., Trottet, B., et al. (2022). Crack propagation speeds in weak snowpack layers. Journal Of Glaciology, 68(269), 557–570.
Résumé: For the release of a slab avalanche, crack propagation within a weak snowpack layer below a cohesive snow slab is required. As crack speed measurements can give insight into underlying processes, we analysed three crack propagation events that occurred in similar snowpacks and covered all scales relevant for avalanche release. For the largest scale, up to 400 m, we estimated crack speed from an avalanche movie; for scales between 5 and 25 m, we used accelerometers placed on the snow surface and for scales below 5 m, we performed a propagation saw test. The mean crack speeds ranged from 36 +/- 6 to 49 +/- 5 m s(-1), and did not exhibit scale dependence. Using the discrete element method and the material point method, we reproduced the measured crack speeds reasonably well, in particular the terminal crack speed observed at smaller scales. Finally, we used a finite element model to assess the speed of different elastic waves in a layered snowpack. Results suggest that the observed cracks propagated as mixed mode closing cracks and that the flexural wave of the slab is responsible for the energy transfer to the crack tip.
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Bernet, M., & Acosta, L. T. (2022). Rising sea level and increasing tropical cyclone frequency are threatening the population of San Andres Island, Colombia, western Caribbean. Bsgf-Earth Sciences Bulletin, 193.
Résumé: The Colombian island of San Andres is a popular tourist destination located about 195 km offshore of the east coast of Nicaragua in the southwestern Caribbean Sea. Together with Providencia and Santa Catalina, San Andres is part of the UNESCO Seaflower Biosphere Reserve. With a 26 km(2) surface area and 78 000 inhabitants, San Andres is one of the most densely populated islands in the Caribbean with on average similar to 3000 inhabitants/km(2). The majority of the population and the mass tourism are concentrated in the low-elevation (0.5-6 m) areas, particularly in the north and along the east coast of the island. These areas are prone to flooding during storm events such as hurricanes Eta and Iota in 2020. A review of the geological, environmental and the socio-economic situation of the island, and the record of tropical cyclones since 1911, shows why the local population has become increasingly vulnerable to storm events and rising sea level. Tropical cyclones may form locally in the southwestern Caribbean or originate in the eastern Caribbean/Atlantic Ocean. The latter tend to be stronger and cause more damage when they reach San Andres. The HURDAT2 dataset shows that the frequency of storm events affecting San Andres has increased in recent decades, with six storms over the past 20 years, including three category 4-5 hurricanes since 2007. Increasing storm frequency and intensity may be linked to increasing sea surface temperatures caused by anthropogenic global warming, although the changes described here may be limited to a relatively small geographical region, as opposed to representing basin wide tropical cyclone behavior. The growing population density since the 1950s has augmented the potential for disaster.
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Bertauts, M., Janots, E., Rossi, M., Duhamel-Achin, I., Boiron, M. - C., Airaghi, L., et al. (2022). A New Alpine Metallogenic Model for the Pb-Ag Orogenic Deposits of Macot-la Plagne and Peisey-Nancroix (Western Alps, France). Geosciences, 12(9).
Résumé: Understanding mass transfer associated with fluids circulation and deformation in the Alpine orogeny is often complex due to common multistage crystallization. For example, in two emblematic and historic Pb-Ag deposits of the French Alps, Macot-la Plagne (MP) and Peisey-Nancroix (PN), a sedimentary or orogenic origin is still debated. To discriminate between the metallogenic models of the two deposits, an integrative methodology combining field, microstructural, mineralogical, thermobarometrical, and geochronological data was here applied for establishing detailed Pressure-Temperature-Time-Deformation (P-T-t-d) mineralization conditions. Both deposits are located in Permo-Triassic quartzite of the External Brianconnais domain along the Internal Brianconnais Front (Internal Western Alps). The ore mainly occurs as veins and disseminated textures containing galena, pyrite, and variable content of tetrahedrite-tennantite and chalcopyrite. Quartz porphyroclasts and sulfide microstructures indicate a dynamic recrystallization of the quartzite during the main fluid mineralization episode. Chlorites and K-white micas (phengite) chemical analysis and thermodynamic modeling from compositional maps indicate an onset of the mineralization at 280 degrees C, with a main precipitation stage at 315 +/- 35 degrees C and 6.25 +/- 0.75 kbar. In situ U-Pb dating on monazite, cogenetic with sulfides, gives ages around 35 Ma for both deposits. The integrative dataset converges for a cogenetic MP-PN Alpine Pb-Ag mineralization during deformation in relation to the thrusting of the “Nappe des Gypses” and the Internal Brianconnais at the metamorphic peak.
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Biggs, J., Anantrasirichai, N., Albino, F., Lazecky, M., & Maghsoudi, Y. (2022). Large-scale demonstration of machine learning for the detection of volcanic deformation in Sentinel-1 satellite imagery. Bulletin Of Volcanology, 84(12).
Résumé: Radar (SAR) satellites systematically acquire imagery that can be used for volcano monitoring, characterising magmatic systems and potentially forecasting eruptions on a global scale. However, exploiting the large dataset is limited by the need for manual inspection, meaning timely dissemination of information is challenging. Here we automatically process similar to 600,000 images of > 1000 volcanoes acquired by the Sentinel-1 satellite in a 5-year period (2015-2020) and use the dataset to demonstrate the applicability and limitations of machine learning for detecting deformation signals. Of the 16 volcanoes flagged most often, 5 experienced eruptions, 6 showed slow deformation, 2 had non-volcanic deformation and 3 had atmospheric artefacts. The detection threshold for the whole dataset is 5.9 cm, equivalent to a rate of 1.2 cm/year over the 5-year study period. We then use the large testing dataset to explore the effects of atmospheric conditions, land cover and signal characteristics on detectability and find that the performance of the machine learning algorithm is primarily limited by the quality of the available data, with poor coherence and slow signals being particularly challenging. The expanding dataset of systematically acquired, processed and flagged images will enable the quantitative analysis of volcanic monitoring signals on an unprecedented scale, but tailored processing will be needed for routine monitoring applications.
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Bissardon, C., Zhang, Y., Labriet, H. R., Berujon, S., Charlet, L., Khan, I. M., et al. (2022). In Vitro Preparation of Actively Maturing Bovine Articular Cartilage Explants for X-Ray Phase Contrast Imaging. Jove-Journal Of Visualized Experiments, (179).
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Bland, G. D., Battifarano, M., del Real, A. E. P., Sarret, G., & Lowry, G., V. (2022). Distinguishing Engineered TiO2 Nanomaterials from Natural Ti Nanomaterials in Soil Using spICP-TOFMS and Machine Learning. Environmental Science & Technology, 56(5), 2990–3001.
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Blommaert, H., Aucour, A. - M., Wiggenhauser, M., Moens, C., Telouk, P., Campillo, S., et al. (2022). From soil to cacao bean: Unravelling the pathways of cadmium translocation in a high Cd accumulating cultivar of Theobroma cacao L. Frontiers In Plant Science, 13.
Résumé: The research on strategies to reduce cadmium (Cd) accumulation in cacao beans is currently limited by a lack of understanding of the Cd transfer pathways within the cacao tree. Here, we elucidated the transfer of Cd from soil to the nib (seed) in a high Cd accumulating cacao cultivar. Here, we elucidated the transfer of Cd from soil to the nib (seed) in a high Cd accumulating cacao cultivar through Cd stable isotope fractionation, speciation (X-Ray Absorption Spectroscopy), and localization (Laser Ablation Inductively Coupled Plasma Mass Spectrometry). The plant Cd concentrations were 10-28 higher than the topsoil Cd concentrations and increased as placenta< nib< testa< pod husk< root< leaf< branch. The retention of Cd in the roots was low. Light Cd isotopes were retained in the roots whilst heavier Cd isotopes were transported to the shoots (Delta (114/110) Cd (shoot-root) = 0.27 +/- 0.02 parts per thousand (weighted average +/- standard deviation)). Leaf Cd isotopes were heavier than Cd in the branches (Delta (114/110) Cd (IF3 leaves-branch) = 0.18 +/- 0.01 parts per thousand), confirming typical trends observed in annual crops. Nibs and branches were statistically not distinguishable (Delta (114/110) Cd (nib-branch) = -0.08 parts per thousand +/- 0.06 parts per thousand), contrary to the leaves and nibs (Delta (114/110) Cd (nib-IF3 leaves) = -0.25 parts per thousand +/- 0.05 parts per thousand). These isotope fractionation patterns alluded to a more direct transfer from branches to nibs rather than from leaves to nibs. The largest fraction (57%) of total plant Cd was present in the branches where it was primarily bound to carboxyl-ligands (60-100%) and mainly localized in the phloem rays and phelloderm of the bark. Cadmium in the nibs was mainly bound to oxygen ligands (60-90%), with phytate as the most plausible ligand. The weight of evidence suggested that Cd was transferred like other nutrients from root to shoot and accumulated in the phloem rays and phelloderm of the branches to reduce the transfer to foliage. Finally, the data indicated that the main contribution of nib Cd was from the phloem tissues of the branch rather than from leaf remobilization. This study extended the limited knowledge on Cd accumulation in perennial, woody crops and revealed that the Cd pathways in cacao are markedly different than in annual crops.
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Boccato, S., Garino, Y., Morard, G., Zhao, B., Xu, F., Sanloup, C., et al. (2022). Amorpheus: a Python-based software for the treatment of X-ray scattering data of amorphous and liquid systems. High Pressure Research, 42(1), 69–93.
Résumé: The diffuse scattering signal of amorphous or liquid systems contains information on the local atomic structure, and this can be related to the density, compressibility, thermal expansion and other thermoelastic properties. However, the analysis and full exploitation of the diffuse scattering signal, in particular for systems under extreme conditions of high pressures and temperatures are difficult to handle. Amorpheus is a Python-based software allowing the determination of the structure factor and the radial distribution function of amorphous and liquid systems. Based on previously reported methodologies, Amorpheus stands out for the implementation of automatic algorithms allowing the user to choose the most suitable parameters for the data treatment and making possible systematic analysis of datasets collected in experiments carried out in Paris-Edinburgh press, multi-anvil apparatus or diamond anvil cell.
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Bore, T., Coperey, A., Wagner, N., Mishra, P. N., Scheuermann, A., & Revil, A. (2022). Experimental determination of frequency- and temperature-dependent electrical properties of water-saturated clays using spectral induced polarization and network analyzer technique. Measurement, 190.
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Bosse, L., Lilensten, J., Gillet, N., Brogniez, C., Pujol, O., Rochat, S., et al. (2022). At the source of the polarisation of auroral emissions: experiments and modeling. Journal Of Space Weather And Space Climate, 12.
Résumé: A polarised radiative transfer model (POMEROL) has been developed to compute the polarisation measured by a virtual instrument in a given nocturnal environment. This single-scattering model recreates real-world conditions (among them atmospheric and aerosol profiles, light sources with complex geometries at the ground and in the sky, terrain obstructions). It has been successfully tested at mid-latitudes where sky emissions are of weak intensity. We show a series of comparisons between POMEROL predictions and polarisation measurements during two field campaigns in the auroral zone, in both quiet and active conditions. These comparisons show the strength of the model to assess the aerosol characteristics in the lower atmosphere by using a mesospheric line. They also show that three main upper atmosphere emissions must be polarised: the green atomic oxygen line at 557.7 nm and the 1st N-2(+) negative band at 391.4 nm (purple) and 427.8 nm (blue). This polarisation can be either created directly at the radiative de-excitation or may occur when the non-polarised emission crosses the ionospheric currents. We provide some of the potentialities it offers in the frame of space weather. These require refinements of the preliminary modeling approach considered in the present study.
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Bosse, L., Lilensten, J., Johnsen, M. G., Gillet, N., Rochat, S., Delboulbe, A., et al. (2022). The polarisation of auroral emissions: A tracer of the E region ionospheric currents. Journal Of Space Weather And Space Climate, 12.
Résumé: It is now established that auroral emissions as measured from the ground are polarised. The question of the information given by this polarisation is still to be explored. This article shows the results of a coordinated campaign between an optical polarimeter and several ground-based instruments, including magnetometers, the EISCAT VHF radar, and complementary luminance meters in the visible domain (Ninox). We show that in the E region, the polarisation is a potential indicator of the ionospheric currents, velocity, and dynamics.
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Bouchayer, C., Aiken, J. M., Thogersen, K., Renard, F., & Schuler, T., V. (2022). A Machine Learning Framework to Automate the Classification of Surge-Type Glaciers in Svalbard. Journal Of Geophysical Research-Earth Surface, 127(7).
Résumé: Surge-type glaciers are present in many cold environments in the world. These glaciers experience a dramatic increase in velocity over short time periods, the surge, followed by an extended period of slow movement, the quiescence. This study aims at understanding why only few glaciers exhibit a transient behavior. We develop a machine learning framework to classify surge-type glaciers, based on their location, exposure, geometry, climatic mass balance and runoff. We apply this approach to the Svalbard archipelago, a region with a relatively homogeneous climate. We compare the performance of logistic regression, random forest, and extreme gradient boosting (XGBoost) machine learning models that we apply to a newly combined database of glaciers in Svalbard. Based on the most accurate model, XGBoost, we compute surge probabilities along glacier centerlines and quantify the relative importance of several controlling features. Results show that the surface and bed slopes, ice thickness, glacier width, climatic mass balance, and runoff along glacier centerlines are the most significant features explaining surge probability for glaciers in Svalbard. A thicker and wider glacier with a low surface slope has a higher probability to be classified as surge-type, which is in good agreement with the existing theories of surging. Finally, we build a probability map of surge-type glaciers in Svalbard. The framework shows robustness on classifying surge-type glaciers that were not previously classified as such in existing inventories but have been observed surging. Our methodology could be extended to classify surge-type glaciers in other areas of the world.
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Bouchet, J., Bottin, F., Antonangeli, D., & Morard, G. (2022). Sound velocities and thermodynamical properties of hcp iron at high pressure and temperature. Journal Of Physics-Condensed Matter, 34(34).
Résumé: Sound velocities and thermodynamical properties of hcp iron have been computed using ab initio calculations over an extended density and temperature range, encompassing the conditions directly relevant for the Earth's inner core. At room temperature, and up to 350 GPa, an excellent agreement is obtained between present results and experimental data for many thermodynamical quantities: phonon density of states, vibrational entropy, heat capacity, Gruneisen parameter and thermal expansion. With increasing temperature, along an isochore, we observe a strong decrease of the phonon frequencies, demonstrating that intrinsic anharmonic effects cannot be neglected. We also carefully compare previous theoretical data for the sound velocities and try to explain the discrepancies observed with experiments. Finally, we propose a temperature dependant Birch's law that we compare with previous experimental work.
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Bouchet, S., Tessier, E., Masbou, J., Point, D., Lazzaro, X., Monperrus, M., et al. (2022). In Situ Photochemical Transformation of Hg Species and Associated Isotopic Fractionation in the Water Column of High-Altitude Lakes from the Bolivian Altiplano. Environmental Science & Technology, 56(4), 2258–2268.
Résumé: Photochemical reactions are major pathways for the removal of Hg species from aquatic ecosystems, lowering the concentration of monomethylmercury (MMHg) and its bioaccumulation in foodwebs. Here, we investigated the rates and environmental drivers of MMHg photodegradation and inorganic Hg (IHg) photoreduction in waters of two high-altitude lakes from the Bolivian Altiplano representing meso- to eutrophic conditions. We incubated three contrasting waters in situ at two depths after adding Hg-enriched isotopic species to derive rate constants. We found that transformations mostly occurred in subsurface waters exposed to UV radiation and were mainly modulated by the dissolved organic matter (DOM) level. In parallel, we incubated the same waters after the addition of low concentrations of natural MMHg and followed the stable isotope composition of the remaining Hg species by compound-specific isotope analysis allowing the determination of enrichment factors and mass-independent fractionation (MIF) slopes (Delta Hg-199/Delta Hg-201) during in situ MMHg photodegradation in natural waters. We found that MIF enrichment factors potentially range from -11 to -19% and average -14.3 +/- 0.6% (1 SE). The MIF slope diverged depending on the DOM level, ranging from 1.24 +/- 0.03 to 1.34 +/- 0.02 for the low and high DOM waters, respectively, and matched the MMHg MIF slope recorded in fish from the same lake. Our in situ results thus reveal (i) a relatively similar extent of Hg isotopic fractionation during MMHg photodegradation among contrasted natural waters and compared to previous laboratory experiments and (ii) that the MMHg MIF recorded in fish is characteristic for the MMHg bonding environment. They will enable a better assessment of the extent and conditions conducive to MMHg photodegradation in aquatic ecosystems.
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Bouchon, M., Socquet, A., Marsan, D., Guillot, S., Durand, V., Gardonio, B., et al. (2022). Observation of rapid long-range seismic bursts in the Japan Trench subduction leading to the nucleation of the Tohoku earthquake. Earth And Planetary Science Letters, 594.
Résumé: Earthquake precursory phenomena like foreshocks are common but the physical processes which produce them and lead to rupture are poorly understood. Looking for clues about these processes, we explore here the long-term evolution of seismicity in a broad section of the Japan Trench slab around the 2011 Tohoku earthquake location and report the existence of long-range seismic bursts moving rapidly (similar to 1-2 days or less) between the deep and the shallow slab. Their presence is evidenced by synchronizations of deep and shallow seismic activities in the slab. Probabilities that these synchronizations could be due to chance are infinitesimal (<10-5). We show that a significant part of the activity in this subduction occurs during these bursts and that they are responsible for the foreshock sequence which preceded the earthquake. These observations support the existence of fluid channels connecting the deep slab, where water is released during dehydration, to the shallow seismogenic zone. (c) 2022 Elsevier B.V. All rights reserved.
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Bouzouaid, L., Lothenbach, B., Fernandez-Martinez, A., & Labbez, C. (2022). Gluconate and hexitols effects on C-S-H solubility. Cement And Concrete Research, 160.
Résumé: This study investigates the effect of gluconate, a carboxylate anion, and three uncharged hexitols, D-sorbitol, Dmannitol and D-galactitol on the solubility of C-S-H. Thermodynamic modeling is used to determine the kind and amount of Ca-organic-silicate-OH complexes that potentially form in the conditions studied. All the organics form complexes with calcium and hydroxide. In addition, heteropolynuclear organics complexes with calcium, hydroxide and silicate are observed at high pH values and high calcium concentrations: Ca(2)Hex(2)(H3SiO4)(2)(OH)(2)(0), Ca(2)Hex(2)(H2SiO4)(OH)(2)(-2) and Ca(3)Gluc(2)(H3SiO4)(2)(OH)(2)(0), with the exception of mannitol. The strength of complexation with silicate decreases in the order gluconate > sorbitol > galactitol. The adsorption of the selected organics on portlandite and C-S-H systems follows the order gluconate > > sorbitol > mannitol similar to galactitol. For C-S-H, a typical Langmuir isotherm is found only when buffered with Ca(OH)(2). The adsorption on C-S-H increases with the Ca/Si ratio.
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Brunet, F., Tisserand, D., Lanson, M., Malvoisin, B., Bertrand, M., & Bonnaud, C. (2022). Real-time monitoring of aqueous Hg2+ reduction dynamics by magnetite/iron metal composite powders synthesized hydrothermally. Water Science And Technology, 86(3), 596–609.
Résumé: An iron-based powder material composed of zerovalent iron (8 wt.%) and magnetite (92 wt.%), has been synthesized hydrothermally at 200 degrees C from zero-valent iron. Its effect on the reduction of aqueous Hg2+ into gaseous Hg-0 has been investigated at ambient conditions for pH comprised between 4 and 8.5. The production of Hg-0 was monitored with an online mercury vapor analyzer at the picogram level for concentrations of iron-based composite of a few tenths of mg L-1. Starting from a solution having an Hg2+ concentration of 25 ng L-1 at pH = 4, a succession of two Hg-0 production events was recorded. The first event is related to the Hg2+ reduction by ZVI which fully dissolved within the first hours. Upon ZVI consumption, pH drifted towards the pH window where magnetite can efficiently reduce Hg2+ at the hour timescale, resulting in a second Hg-0 production peak. The combined use of ZVI and magnetite to remove aqueous Hg2+ by formation of Hg-0 (volatile) under mild acidic pH allows (1) to maximize the Hg2+ reduction rate and (2) to take benefit of the longer lifetime of magnetite compared to ZVI.
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Cabrera, L., Poli, P., & Frank, W. B. (2022). Tracking the Spatio-Temporal Evolution of Foreshocks Preceding the Mw 6.1 2009 L'Aquila Earthquake. Journal Of Geophysical Research-Solid Earth, 127(3).
Résumé: How faulting processes lead to a large earthquake is a fundamental question in seismology. To better constrain this pre-seismic stage, we create a dense seismic catalog via template matching to analyze the precursory phase of the Mw 6.1 L'Aquila earthquake that occurred in central Italy in 2009. We estimate several physical parameters in time, such as the coefficient of variation, the seismic moment release, the effective stress drop, and analyze spatio-temporal patterns to study the evolution of the sequence and the earthquake interactions. We observe that the precursory phase experiences multiple accelerations of the seismicity rate that we divide into two main sequences with different signatures and features: the first part exhibits weak earthquake interactions, quasi-continuous moment release, slow spatial migration patterns, and a lower effective stress drop, pointing to aseismic processes. The second sequence exhibits strong temporal clustering, fast seismicity expansion, and a larger effective stress drop typical of a stress transfer process. We interpret the differences in seismicity behaviors between the two sequences as distinct physical mechanisms that are controlled by different physical properties of the fault system. We conclude that the L'Aquila earthquake is preceded by a complex preparation, made up of different physical processes over different time scales on faults with different physical properties.
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Cagnon, B., Daval, D., Cabie, M., Lemarchand, D., & Gin, S. (2022). A comparative study of the dissolution mechanisms of amorphous and crystalline feldspars at acidic pH conditions. Npj Materials Degradation, 6(1).
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Callefo, F., Ricardi-Branco, F., Pacheco, M. L. A. F., Cardoso, A. R., Noffke, N., Teixeira, V. de C., et al. (2022). Evidence for metabolic diversity in Meso-Neoproterozoic stromatolites (Vazante Group, Brazil). Frontiers In Earth Science, 10.
Résumé: Deciphering the evolution of ecological interactions among the metabolic types during the early diversification of life on Earth is crucial for our understanding of the ancient biosphere. The stromatolites from the genus Conophyton cylindricus represent a datum for the Proterozoic (Meso to Neoproterozoic) on Earth. Their typical conical shape has been considered a result of a competition between microorganisms for space, light and nutrients. Well-preserved records of this genus from the “Paleontological Site of Cabeludo ”, Vazante Group, Sao Francisco Craton (Southern Brazil) present in situ fossilized biofilms, containing preserved carbonaceous matter. Petrographic and geochemical analyses revealed an alternation between mineral laminae (light grey laminae) and fossilized biofilms (dark grey laminae). The dark grey laminae comprise three different biofilms recording a stratified microstructure of microbial communities. These three biofilms composing the dark grey laminae tend to be organized in a specific pattern that repeats through the stromatolite vertical section. Iron and manganese are distributed differently along the dark and light grey laminae; X-ray absorption and luminescence data showed possible different areas with authigenic iron and iron provided from diagenetic infiltration. Cryptocrystalline apatite in the lowermost biofilms in each dark grey laminae may suggest past metabolic activity of sulfide-oxidizing bacteria. These findings suggest that the microorganisms reached a complex metabolic diversification in order to maintain an equilibrium situation between the three different biofilms along the vertical section of the structures, thus benefiting the whole microbial community. This means that the stromatolites from the Conophyton genus may have formed as a result of a greater complexity of interactions between microorganisms, and not only from competition between photosynthesizers.
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Cao, J., Brossier, R., Gorszczyk, A., Metivier, L., & Virieux, J. (2022). 3-D multiparameter full-waveform inversion for ocean-bottom seismic data using an efficient fluid-solid coupled spectral-element solver. Geophysical Journal International, 229(1), 671–703.
Résumé: Ocean-bottom seismic acquisition systems deployed on the seabed give access to three-component geophone data and hydrophone data. Compared with conventional streamer acquisitions, the separation of sources and receivers makes it possible to increase the maximum offset and azimuth coverage for improving the illumination at depth. Furthermore, the three-component geophones naturally capture elastic wave propagation effects. While this information is mostly overlooked up to now, reconstructing jointly P- and S-wave velocities would significantly improve the subsurface characterization. To achieve a 3-D high-resolution multiparameter reconstruction, we design an efficient 3-D fluid-solid coupled full waveform modelling and inversion engine. In this engine, fluid and solid domains are divided explicitly and handled with the acoustic and elastic wave equations, respectively. The numerical implementation is based on a time-domain spectral-element method (SEM) with a flexible 3-D Cartesian-based hexahedral mesh, which contributes to an accurate coupling of the acoustic and elastic wave equations and high computational efficiency through domain-decomposition based parallelization. We select the best acoustic-elastic coupled formulations among 4 possibilities with criteria based on numerical accuracy and implementation efficiency. Moreover, we propose a specific hybrid approach for the misfit gradient building so as to use a similar modelling solver for both forward and adjoint simulations. Synthetic case studies on a 3-D extended Marmousi-II model and a 3-D deep-water crustal-scale model illustrate how our modelling and inversion engine can efficiently extract information from ocean-bottom seismic data to simultaneously reconstruct both P- and S-wave velocities within a full waveform inversion framework.
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Cao, K., Tian, Y., van der Beek, P., Wang, G., Shen, T., Reiners, P., et al. (2022). Southwestward growth of plateau surfaces in eastern Tibet. Earth-Science Reviews, 232.
Résumé: Both the kinematics and dynamics of topographic growth of the Tibetan Plateau remain debated, despite their significance for understanding the evolution of continental lithospheric geodynamics, climate, and biodiversity in Asia. Topographic swath profiles reveal the diversity of high-elevation, low-relief plateau surfaces or “relict landscapes” throughout the southeast Qiangtang, northeast Qiangtang, and Songpan-Garze-Yidun terranes in eastern Tibet, including the Zuogong, Markam, Litang, and Kangding plateaux from southwest to northeast. New geo-thermochronology data combined with morphotectonic analysis of the Qiangtang terrane underscore that the Lancangjiang thrust belt, separating the Zuogong and Markam plateaux, is a prominent tectonic and geomorphic boundary that limits high topography at mean elevations of >5000 m around the eastern Himalayan syntaxis. Inverse thermal-history modelling of thermochronological data reveals accelerated cooling at 40-35 Ma at rates of 1.2 +/- 0.4 mm/yr in the Zuogong plateau and contemporaneous slow cooling of 0.10 +/- 0.02 mm/yr in the Markam and Weixi plateaux in eastern Tibet, which is interpreted as recording activity of the Lancangjiang and Markam fold-and-thrust belts. These data, together with coeval cooling signals in the central and southeast Qiangtang terrane, indicate widespread crustal shortening and thickening throughout the terrane that likely led to surface uplift to near-present-day elevations by the late Eocene. Very slow cooling at a rate of <0.5 degrees C/Myr rules out significant tectonically-driven surface uplift and erosion of the Markam plateau since then. A second stage of rapid exhumation at ca. 20 Ma, at rates of 1.0-1.3 mm/yr, in the Zuogong plateau in the hanging wall of the Lancangjiang thrust, sharply contrasts to exhumation rates of 0.02 mm/yr for the Markam plateau in the footwall and suggests reactivation of the Lancangjiang thrust belt at that time. The transition to slow denudation after ca. 20 Ma for the Zuogong plateau in the southwest Qiangtang suggests tectonic and topographic stabilization of this low-relief surface at least 15-20 Myr later than the Markam plateau. In contrast, a compilation of existing low-temperature thermochronology data in the Songpan-Garze-Yidun terranes shows much older ages for stabilization of the low-relief surfaces in the Litang and Kangding plateaux by 80-60 Ma. We thus suggest that tectonic and topographic stabilization of plateau surfaces in eastern Tibet has occurred at 80-60 Ma, 40-35 Ma, and similar to 20 Ma in the Songpan-Garze-Yidun, northeast Qiangtang, and southwest Qiangtang, respectively. The southwestward piecemeal expansion of small plateaux suggests that the high-elevation, low-relief landscape of eastern Tibet has been constructed during distinct orogenic episodes prior to and during the early stages of India-Asia collision. A late stage of tectonic activity related to northward indentation of the Indian plate during the Neogene mostly remodeled the outer rims of the plateaux and the valleys that delineate transcurrent faults, while drainage expansion and integration triggered river incision in eastern Tibet.
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Carocci, E., Truche, L., Cathelineau, M., Caumon, M. - C., & Bazarkina, E. F. (2022). Tungsten (VI) speciation in hydrothermal solutions up to 400 degrees C as revealed by in-situ Raman spectroscopy. Geochimica Et Cosmochimica Acta, 317, 306–324.
Résumé: Tungsten (VI) speciation in hydrothermal solutions is investigated through in-situ Raman spectroscopy coupled with the fused silica glass capillary technique at temperatures up to 400 degrees C. The effect of temperature, pH, chlorinity and carbonate speciation are evaluated in systems with highly soluble salts Na2WO4 and Na6W12O39. At all investigated temperatures, the tungstate ion WO42- (927 cm-1) is the only W species in solution at pH > 10. At a given pH, the presence of dissolved carbonates and chloride does not affect the tungsten speciation. Tungsten polymers remain stable up to 400 degrees C under acidic to circum-neutral pH conditions and total tungsten concentration above 0.01 mol_skgH2O mers, namely [W7O24]6- (paratungstate-A, -960 cm-1), [W10O32]4- (tungstate-Y, -970 cm-1), and a-[H2W12O40]6- (ametatungstate, -990 cm-1), only the hepta- and dodeca-tungstate are stable at elevated temperature. Combined with revised literature data, these results allow the thermodynamic stability constants of these W polymers to be constrained, enabling quantitative predictions of their relative abundance at temperatures up to 300 degrees C. These predictions suggest that W polymerization occurs under hydrothermal conditions even at low W concentration (down to 10-3 mol center dot kgH2O-1 ) under acidic conditions. These observations imply that the currently available geochemical models on W transport and deposition in deep and hot geological fluids need to be revised. (c) 2021 Elsevier Ltd. All rights reserved.
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Carrara, A., Lesage, P., Burgisser, A., Annen, C., & Bergantz, G. W. (2022). The dispersive velocity of compressional waves in magmatic suspensions. Geophysical Journal International, 228(3), 2122–2136.
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Carrero, S., Fernandez-Martinez, A., Perez-Lopez, R., Cama, J., Dejoie, C., & Miguel Nieto, J. (2022). Effects of aluminum incorporation on the schwertmannite structure and surface properties. Environmental Science-Processes & Impacts, 24(9), 1383–1391.
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Carretier, S., Audemard, F., Audin, L., Hidalgo, S., Le Pennec, J. -l., Mora, H., et al. (2022). Introductory paper of the 8th International Symposium on Andean Geodynamics (ISAG) special number. Journal Of South American Earth Sciences, 116.
Résumé: The International Symposium on Andean Geodynamics (ISAG) is an international conference that was held, on average, every 3-4 years in different European cities between 1990 (Grenoble) and 2008 (Nice). These symposia usually offer an opportunity for researchers from Latin American countries and Europe as well as other countries to review the state of knowledge in geosciences on the Andes. After a long period without an edition, the 8th ISAG was organized for the first time in a Latin American country, Ecuador, from 24th to 26th September 2019. The organizing committee led by Pablo Samaniego relied heavily on the Instituto Geofisico of the Escuela Politecnica Nacional (IG-EPN) and the Institut de Recherche pour le Developpement (IRD), in particular through its office in Quito, and through the Laboratoire Mixte International in France and Ecuador: “Seismes et Volcans dans les Andes du Nord”(LMI-SVAN); and the French Embassy in Ecuador. Field trips in tectonics, seismotectonics and volcanology at emblematic sites in Ecuador were organized by researchers from the IRD (Isterre and LMV), the Institut de Radio Protection Nucleaire (IRSN), IG-EPN and the University of Geneva. Four invited speakers gave presentations: Peter Molnar (University of Boulder) on the mechanisms of the Andes uplift, Suzanne Kay (Cornell University) on its magmatism, Victor Ramos (University of Buenos Aires) on the scientific approaches developed through time for the Andean orogeny and Eric Calais (Ecole Normale Superieure de Paris) on the difficulty of dialog between seismic risk specialists and the authorities in Haiti. The symposium also provided an opportunity for more than 250 participants to meet, with more than 80 oral presentations and over 150 posters. As a result of this conference, the Editor of the Journal of South American Earth Sciences proposed to the organizing committee to publish a special issue on the contours of these presentations. Following the peer review process, 19 papers are published in this special issue. These manuscripts reflect the various disciplinary fields, geophysics and deep imaging, tectonics, volcanism, geomorphology and seismic hazard, from the local scale to the Andes as a whole. Not surprisingly, a higher density of works is found in Ecuador and the northern Andes (Figure 1). As this collection of articles reflects the outlines of a symposium and not a specific scientific question, our aim here is not to develop a synthesis of current knowledge on the Andes. We therefore present these articles in sequence, by discipline, although this categorization may appear subjective since some articles are multidisciplinary.
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Carvalho, P. T. C., da Silva, S. L. E. F., Duarte, E. F., Brossier, R., Corso, G., & de Araujo, J. M. (2022). Full waveform inversion based on the non-parametric estimate of the probability distribution of the residuals. Geophysical Journal International, 229(1), 35–55.
Résumé: In an attempt to overcome the difficulties of the full waveform inversion (FWI), several alternative objective functions have been proposed over the last few years. Many of them are based on the assumption that the residuals (differences between modelled and observed seismic data) follow specific probability distributions when, in fact, the true probability distribution is unknown. This leads FWI to converge to an incorrect probability distribution if the assumed probability distribution is different from the real one and, consequently it may lead the FWI to achieve biased models of the subsurface. In this work, we propose an objective function which does not force the residuals to follow a specific probability distribution. Instead, we propose to use the non-parametric kernel density estimation technique (KDE) (which imposes the least possible assumptions about the residuals) to explore the probability distribution that may be more suitable. As evidenced by the results obtained in a synthetic model and in a typical P-wave velocity model of the Brazilian pre-salt fields, the proposed FWI reveals a greater potential to overcome more adverse situations (such as cycle-skipping) and also a lower sensitivity to noise in the observed data than conventional L-2- and L-1-norm objective functions and thus making it possible to obtain more accurate models of the subsurface. This greater potential is also illustrated by the smoother and less sinuous shape of the proposed objective function with fewer local minima compared with the conventional objective functions.
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Castro-Cruz, D., Gatti, F., Lopez-Caballero, F., Hollender, F., El Haber, E., & Causse, M. (2022). Blind broad-band (0-10 Hz) numerical prediction of the 3-D near field seismic response of an M(W)6.0 extended fault scenario: application to the nuclear site of Cadarache (France). Geophysical Journal International, 232(1), 581–600.
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Caudron, C., Aoki, Y., Lecocq, T., De Plaen, R., Soubestre, J., Mordret, A., et al. (2022). Hidden pressurized fluids prior to the 2014 phreatic eruption at Mt Ontake. Nature Communications, 13(1).
Résumé: A large fraction of volcanic eruptions does not expel magma at the surface. Such an eruption occurred at Mt Ontake in 2014, claiming the life of at least 58 hikers in what became the worst volcanic disaster in Japan in almost a century. Tens of scientific studies attempted to identify a precursor and to unravel the processes at work but overall remain inconclusive. By taking advantage of continuous seismic recordings, we uncover an intriguing sequence of correlated seismic velocity and volumetric strain changes starting 5 months before the eruption; a period previously considered as completely quiescent. We use various novel approaches such as covariance matrix eigenvalues distribution, cutting-edge deep-learning models, and ascribe such velocity pattern as reflecting critically stressed conditions in the upper portions of the volcano. These, in turn, later triggered detectable deformation and earthquakes. Our results shed light onto previously undetected pressurized fluids using stations located above the volcano-hydrothermal system and hold great potential for monitoring.
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Caudron, C., Soubestre, J., Lecocq, T., White, R. S., Brandsdottir, B., & Krischer, L. (2022). Insights into the dynamics of the 2010 Eyjafjallajokull eruption using seismic interferometry and network covariance matrix analyses. Earth And Planetary Science Letters, 585.
Résumé: Applying seismic interferometry and network covariance matrix-based analyses to detect and locate the source of volcanic tremor during the 2010 Eyjafjallajokull effusive flank and explosive-effusive summit eruptions has provided new insights into this iconic event. The tremor source locations derived from the network covariance matrix approach were spatially distinct during the two eruptions. The tremor was radiated between the surface and 5-6 km depth during the effusive flank eruption, including an apparently progressive upward migration in early April 2010, but was strictly confined to the surface during the summit eruption. Each phase of the summit eruption left a distinct fingerprint in the seismic records. Effusive phases radiated continuous tremor between 0.6 and 5 Hz, whereas explosive phases produced tremor in a more pulsating fashion over a wider frequency band (0.2-10 Hz). A period of intermittent tremor bursts (called banded tremor) on 15 April, associated with formation of a new vent at the summit, was most likely generated by magma-gas-meltwater interaction within a subglacial enclosure. The banded tremor ceased following an abrupt draining of the newly formed subglacial cauldron, resulting in a large slurry glacial meltwater flood (jokulhlaup). This study highlights the importance of new data processing methodologies for future monitoring of volcanic tremor in real-time. (c) 2022 Elsevier B.V. All rights reserved.
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Caudron, C., Vandemeulebrouck, J., & Sohn, R. A. (2022). Turbulence-induced bubble nucleation in hydrothermal fluids beneath Yellowstone Lake. Communications Earth & Environment, 3(1).
Résumé: Volcanic systems generate large amounts of gas, and understanding gas fluxes is a fundamental aspect of volcanology and hazard mitigation. Volcanic gases can be challenging to measure, but acoustic methods hold promise in underwater environments because gas bubbles are powerful sound sources. We deployed an acoustic system to study the nature of gas discharge at a large (similar to 30 MW) thermal field on the floor of Yellowstone Lake, which has experienced numerous hydrothermal explosions since the last glaciation (similar to 13.4 ka). We find that small (<10 Pa) turbulent flow instabilities trigger the nucleation of CO2 bubbles in the saturated fluids. The observation of CO2 bubbles nucleating in hydrothermal fluids due to small pressure perturbations informs our understanding of hydrothermal explosions in Yellowstone Lake, and demonstrates that acoustic data in underwater environments can provide insight into the stability of gas-rich systems, as well as gas fluxes.
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Celorio, M., Chaljub, E., Margerin, L., & Stehly, L. (2022). Propagation of 2-D SH waves in random media: Insights from ab initio numerical simulations and transport theory. Frontiers In Earth Science, 10.
Résumé: Increasing the frequency range of physics-based predictions of earthquake ground motions requires to account for small-scale heterogeneities, which can only be described in a stochastic way. Although many studies have addressed the impact of random heterogeneities on ground motion intensity parameters obtained by numerical simulation, very few have verified the accuracy of their numerical solutions or controlled the scattering regime they were simulating. Here we present a comprehensive analysis of SH wave propagation in 2D random media which covers a broad range of propagation regimes from ballistic to diffusive. The coherent and incoherent parts of the wavefield are examined independently. The random media consist in correlated density and velocity fluctuations described by a von Karman autocorrelation function with a Hurst coefficient of 0.25 and a correlation length a = 500 m. The Birch correlation coefficient which relates density to velocity fluctuations takes 4 possible values between 0.5 and 1, and the standard deviation of the perturbations is either 5% or 10%. Spectral element simulations of SH wave propagation excited by a plane wave are performed for normalized wavenumbers (ka) up to 5. Analysis of the decay of the coherent wave amplitude, obtained through different averaging procedures, allows for a direct measure of the scattering attenuation, which we successfully compare with the predictions of the Dyson mean field theory. We also present the comparison between the energy envelopes measured from the synthetics and their theoretical counterpart provided by the radiative transfer theory and the diffusion approximation. Excellent agreement is found between numerical simulations and theoretical predictions of radiative transfer theory for the mean intensity. The numerical study highlights the difference of attenuation length between the mean field and the mean intensity. In the forward scattering regime, the peak intensity appears to decay exponentially over a length scale known as the transport mean free path. Furthermore, the fluctuations of intensity in the ballistic peak exhibit a transition from Log-normal to Exponential statistics. This transition occurs for a propagation distance of the order of the mean free path, which offers an alternative method of estimating this parameter.
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Chaboche, P. - A., Pointurier, F., Sabatier, P., Foucher, A., Tiecher, T., Minella, J. P. G., et al. (2022). 240Pu/239Pu signatures allow refining the chronology of radionuclide fallout in South America. Science Of The Total Environment, 843.
Résumé: Atmospheric nuclear tests (1945-1980) have led to radioactive fallout across the globe. French tests in Polynesia (1966-1974) may influence the signature of fallout in South America in addition to those conducted by USA and former USSR until 1963 in the Northern hemisphere. Here, we compiled the 240Pu/239Pu atom ratios reported for soils of South America and conducted additional measurements to examine their latitudinal distributions across this continent. Significantly lower ratio values were found in the 20-45 degrees latitudinal band (0.04 to 0.13) compared to the rest of the continent (up to 0.20) and attributed to the contribution of the French atmospheric tests to the ultra-trace plutonium levels found in these soils. Based on sediment cores collected in lakes of Chile and Uruguay, we show the added value of measuring 240Pu/239Pu atom ratios to refine the age models of environmental archives in this region of the world.
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Charlet, L., Tournassat, C., Greneche, J. - M., Wersin, P., Gehin, A., & Hadi, J. (2022). Mossbauer spectrometry insights into the redox reactivity of Fe-bearing phases in the environment. Journal Of Materials Research, .
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Charlety, A., Le Breton, M., Baillet, L., & Larose, E. (2022). Long-term Monitoring of Soil Surface Deformation with RFID.
Résumé: Passive Radio-Frequency Identification (RFID) has been used to monitor landslide displacement since approximately 5 years. This method allows soil displacement estimation at a high spatio-temporal resolution, and at a relatively low cost. In perspective of the previous years, this paper proposes to summarize the various challenges encountered with the long-term outdoor RFID localization method, and presents solutions that were implemented to overcome these challenges. Finally, displacement results from three monitored sites are shown in order to validate the implemented solutions.
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Charlety, A., Le Breton, M., Larose, E., & Baillet, L. (2022). 2D Phase-Based RFID Localization for On-Site Landslide Monitoring. Remote Sensing, 14(15).
Résumé: Passive radio-frequency identification (RFID) was recently used to monitor landslide displacement at a high spatio-temporal resolution but only measured 1D displacement. This study demonstrates the tracking of 2D displacements, using an array of antennas connected to an RFID interrogator. Ten tags were deployed on a landslide for 12 months and 2D relative localization was performed using a phase-of-arrival approach. A period of landslide activity was monitored through RFID and displacements were confirmed by reference measurements. The tags showed displacements of up to 1.2 m over the monitored period. The centimeter-scale accuracy of the technique was confirmed experimentally and theoretically for horizontal localization by developing a measurement model that included antenna and tag positions, as well as multipath interference. This study confirms that 2D landslide displacement tracking with RFID is feasible at relatively low instrumental and maintenance cost.
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Cheaib, A., Lacroix, P., Zerathe, S., Jongmans, D., Ajorlou, N., Doin, M. - P., et al. (2022). Landslides induced by the 2017 Mw7.3 Sarpol Zahab earthquake (Iran). Landslides, 19(3), 603–619.
Résumé: Landslides are the main secondary effects of earthquakes in mountainous areas. The spatial distribution of these landslides is controlled by the local seismic ground motion and the local slope stability. While gravitational instabilities in arid and semi-arid environments are understudied, we document the landslides triggered by the Sarpol Zahab earthquake (November 12, 2017, Mw7.3, Iran/Iraq border), the largest event ever recorded in the semi-arid Zagros Mountains. An original earthquake-induced landslide inventory was derived, encompassing landslides of various sizes and velocities (from rapid disrupted rockfalls to slow-moving coherent landslides). This inventory confirms the low level of triggered landslides in semi-arid environments. It also displays clear differences in the spatial and volumetric distributions of earthquake-induced landslides, having 386 rockfalls of limited size triggered around the epicenter, and 9 giant (areas of ca. 10(6) m(2)) active and ancient deep-seated landslides coseismically accelerated at locations up to 180 km from the epicenter. This unusual distant triggering is discussed and interpreted as an interaction between the earthquake source properties and the local geological conditions, emphasizing the key role of seismic ground motion variability at short spatial scales in triggering landslides. Finally, the study documents the kinematics of slow-moving ancient landslides accelerated by earthquakes, and opens up new perspectives for studying landslide triggering over short (similar to 1-10 years) and long-time (similar to 1000-10,000 years) periods.
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Chen, K. H., Yeh, T. - C., Chen, Y., Johnson, C. W., Lin, C. - H., Lai, Y. - C., et al. (2022). Characteristics and impact of environmental shaking in the Taipei metropolitan area. Scientific Reports, 12(1).
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Chen, L. (2022). Multiplicity in an optimised kinematic dynamo. Geophysical And Astrophysical Fluid Dynamics, 116(4), 290–304.
Résumé: Multiplicity in optimal kinematic dynamos exists for certain types of symmetry classes and boundary conditions, at least near the lowest dynamo onset R-mc. Here we investigate the NNT type dynamo generated by steady flows with impermeable boundary conditions in a cube, where the letter N or T stands for pseudo-vacuum or superconducting boundary conditions along x, y, z directions, respectively. We find the top two of the three branches in the neighbourhood of R-mc = 7.54 have their growth rates crossed over at R-m approximate to 9. Within each branch, the spatial structure of the optimal velocity field gradually shifts with respect to R-m. At about 30% above R-mc, the original optimal branch has developed distinct combinations of dominant Fourier modes. In contrast, the first suboptimal branch shows the least change in structure. We then follow the evolution of selected optimised solutions when R-m varies until it becomes unstable. Specific modes in the flow that can destabilise the dynamo are identified. Within the range surveyed, we find that there can be one to two dynamo windows. All three branches generate a steady dynamo near R-mc, but the first suboptimal branch can generate an oscillatory dynamo at about eight times R-mc, and for both suboptimal branches, the growth rate reaches saturation approximately at R-m > 100. We find the two suboptimal branches create a more robust dynamo action supercritically.
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Chen, S., Chen, Y., Guillot, S., & Li, Q. (2022). Change in Subduction Dip Angle of the Indian Continental Lithosphere Inferred From the Western Himalayan Eclogites. Frontiers In Earth Science, 9.
Résumé: The occurrence of ultrahigh-pressure (UHP) and high-pressure (HP) rocks in the Himalayan orogen has been conventionally attributed to the different subduction dip angles along the strike. The western Himalayan UHP eclogites point to a steep continental subduction in the Eocene. The present-day geophysical data show low subduction dip angles of the Indian lithosphere beneath southern Tibet and Karakoram, implying that a shift from steep to low-angle subduction probably happened in the western Himalaya. However, the timing and mechanism of such a subduction-angle change are still unknown. Here we present a combined analysis of zircon geochronology and geochemistry of eclogites and gneiss in the Stak massif, western Himalaya. Metamorphic zircons equilibrated with garnet and omphacite show flat heavy rare earth element patterns without Eu anomalies and, thus, yield similar eclogite-facie ages of ca. 31 Ma. The Stak HP eclogite-facie metamorphism is at least 15 Ma younger than those measured in the western Himalayan UHP eclogites, but broadly contemporaneous with other Himalayan HP rocks. Therefore, all the Himalayan HP rocks record higher peak geothermal gradients and younger ages than those of the UHP rocks. Our new data, combined with the magmatic lull observed in the Kohistan-Ladakh-Gangdese arc and with the convergent rate of the Indian plate, suggest a change in subduction dip angle over time. Consequently, we suggest that the entire Indian continental lithosphere experienced an approximately coherent shift from steep to low-angle subduction after the breakoff of the Neo-Tethyan slab since the middle Eocene. This critical change in subduction geometry is interpreted to be responsible for the transition from continental subduction to collision dynamics.
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Chevalier, M. - L., Replumaz, A., Wang, S., Pan, J., Bai, M., Li, K., et al. (2022). Limit of monsoonal precipitation in southern Tibet during the Last Glacial Maximum from relative moraine extents. Geomorphology, 397.
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Chevalier, M. - L., Wang Shiguang, Replumaz, A., & Li Haibing. (2022). Marine Oxygen Isotope Stage (MIS)-6 Glacial Advances on the Tibetan Plateau More Extensive than during MIS-2 due to More Abundant Precipitation. Acta Geologica Sinica-English Edition, 96(5), 1484–1494.
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Chevrot, S., Sylvander, M., Villasenor, A., Diaz, J., Stehly, L., Boue, P., et al. (2022). Passive imaging of collisional orogens: a review of a decade of geophysical studies in the Pyrenees. Bsgf-Earth Sciences Bulletin, 193.
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Cisneros-Lazaro, D., Adams, A., Guo, J., Bernard, S., Baumgartner, L. P., Daval, D., et al. (2022). Fast and pervasive diagenetic isotope exchange in foraminifera tests is species-dependent. Nature Communications, 13(1).
Résumé: Oxygen isotope compositions of fossil foraminifera tests are commonly used proxies for ocean paleotemperatures, with reconstructions spanning the last 112 million years. However, the isotopic composition of these calcitic tests can be substantially altered during diagenesis without discernible textural changes. Here, we investigate fluid-mediated isotopic exchange in pristine tests of three modern benthic foraminifera species (Ammonia sp., Haynesina germanica, and Amphistegina Iessonii) following immersion into an O-18-enriched artificial seawater at 90 degrees C for hours to days. Reacted tests remain texturally pristine but their bulk oxygen isotope compositions reveal rapid and species-dependent isotopic exchange with the water. NanoSIMS imaging reveals the 3-dimensional intra-test distributions of O-18-enrichment that correlates with test ultra-structure and associated organic matter. Image analysis is used to quantify species level differences in test ultrastructure, which explains the observed species-dependent rates of isotopic exchange. Consequently, even tests considered texturally pristine for paleo-climatic reconstruction purposes may have experienced substantial isotopic exchange; critical paleo-temperature record re-examination is warranted.
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Combey, A., Audin, L., Gandreau, D., Benavente, C., Rosell, L., & Marconato, L. (2022). Reassessing the seismic hazard in the Cusco area, Peru: New contribution coming from an archaeoseismological survey on Inca remains. Quaternary International, 634, 81–98.
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Combey, A., Mercerat, D. E., Gueguen, P., Langlais, M., & Audin, L. (2022). Postseismic Survey of a Historic Masonry Tower and Monitoring of Its Dynamic Behavior in the Aftermath of Le Teil Earthquake (Ardeche, France). Bulletin Of The Seismological Society Of America, 112(2), 1101–1119.
Résumé: On 11 November 2019, an M-w 4.9 earthquake struck the middle Rhone valley (South-East France) producing moderate to severe damage in the town of Le Teil and its surroundings. This unexpected event stressed the vulnerability of the French cultural built heritage to a moderate seismic hazard. Commonly applied to modern civil engineering structures, passive seismic methods are still lacking on historic constructions to understand properly the different factors driving their dynamic behavior. In this article, the results of a two-month seismic monitoring survey carried out shortly after the Le Teil mainshock in a historic masonry tower are presented and discussed. Located only 5 km south of the epicenter, the Gate Tower of Viviers (eleventh century) was instrumented with four highly sensitive seismic nodes. Ambient vibrations, as well as aftershocks and quarry blasts from the nearby Le Teil quarry, were recorded and used in the analysis. Through vibration-based analysis, the article addresses three relevant aspects of the dynamic response of ancient masonry structures. We discuss first the differences in the building's response induced by the three reported types of vibrations, focusing on the particular signal characteristics of shallow aftershocks and quarry blasts. Then, we apply the Random Decrement Technique (RDT) to track the dynamic behavior variations over two months and to discuss the role of the environmental conditions in the slight fluctuations of the structural modal parameters (natural frequencies, damping coefficients) of unreinforced masonry structures. We also show evidence of the nonlinear elastic behavior under both weak seismic and atmospheric loadings. The correlation between the presence of heterogeneities in the construction materials and the nonlinear threshold supports the relevance of such types of monitoring surveys as a valuable tool for future modeling works and conservation efforts.
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Connelly, D. P., Bull, J. M., Flohr, A., Schaap, A., Koopmans, D., Blackford, J. C., et al. (2022). Assuring the integrity of offshore carbon dioxide storage. Renewable & Sustainable Energy Reviews, 166.
Résumé: Carbon capture and storage is a key mitigation strategy proposed for keeping the global temperature rise below 1.5 degrees C. Offshore storage can provide up to 13% of the global CO2 reduction required to achieve the Intergovernmental Panel on Climate Change goals. The public must be assured that potential leakages from storage reservoirs can be detected and that therefore the CO2 is safely contained. We conducted a controlled release of 675 kg CO2 within sediments at 120 m water depth, to simulate a leak and test novel detection, quantification and attribution approaches. We show that even at a very low release rate (6 kg day(-1)), CO2 can be detected within sediments and in the water column. Alongside detection we show the fluxes of both dissolved and gaseous CO2 can be quantified. The CO2 source was verified using natural and added tracers. The experiment demonstrates that existing technologies and techniques can detect, attribute and quantify any escape of CO2 from sub-seabed reservoirs as required for public assurance, regulatory oversight and emissions trading schemes.
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Corbi, F., Bedford, J., Poli, P., Funiciello, F., & Deng, Z. (2022). Probing the seismic cycle timing with coseismic twisting of subduction margins. Nature Communications, 13(1).
Résumé: Assessing the timing of great megathrust earthquakes is together crucial for seismic hazard analysis and deemed impossible. Geodetic instrumentation of subduction zones has revealed unexpected deformation patterns at subduction segments adjacent to those that hosted recent mega-earthquakes: coastal sites move landward with faster velocities than before the earthquake. Here, we show observations from the largest and best-monitored megathrust earthquakes, and from a scaled analog model, to reveal that these events create coseismic and postseismic deformation patterns typical of a complete gear-like rotation about a vertical axis, hereafter called twisting. We find that such twisting alters the interseismic velocity field of adjacent subduction segments depending on the time since the last earthquake. Early interactions accelerate while late interactions decelerate local kinematics. This finding opens the possibility of using megathrust earthquakes, the characteristics of the twisting pattern, and the ensuing geodetic velocity changes, as a proxy for estimating the timing of the seismic cycle at unruptured segments along the margin. Satellite geodesy and downscaled laboratory experiments reveal that great subduction earthquakes trigger step changes in kinematics of neighboring segments. This signal is potentially informative of the timing of the seismic cycle.
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Cossa, D., Knoery, J., Banaru, D., Harmelin-Vivien, M., Sonke, J. E., Hedgecock, I. M., et al. (2022). Mediterranean Mercury Assessment 2022: An Updated Budget, Health Consequences, and Research Perspectives. Environmental Science & Technology, 56(7), 3840–3862.
Résumé: Mercury (Hg) and especially its methylated species (MeHg) are toxic chemicals that contaminate humans via the consumption of seafood. The most recent UNEP Global Mercury Assessment stressed that Mediterranean populations have higher Hg levels than people elsewhere in Europe. The present Critical Review updates current knowledge on the sources, biogeochemical cycling, and mass balance of Hg in the Mediterranean and identifies perspectives for future research especially in the context of global change. Concentrations of Hg in the Western Mediterranean average 0.86 +/- 0.27 pmol L-1 in the upper water layer and 1.02 +/- 0.12 pmol L-1 in intermediate and deep waters. In the Eastern Mediterranean, Hg measurements are in the same range but are too few to determine any consistent oceanographical pattern. The Mediterranean waters have a high methylation capacity, with MeHg representing up to 86% of the total Hg, and constitute a source of MeHg for the adjacent North Atlantic Ocean. The highest MeHg concentrations are associated with low oxygen water masses, suggesting a microbiological control on Hg methylation, consistent with the identification of hgcA-like genes in Mediterranean waters. MeHg concentrations are twice as high in the waters of the Western Basin compared to the ultra-oligotrophic Eastern Basin waters. This diHerence appears to be transferred through the food webs and the Hg content in predators to be ultimately controlled by MeHg concentrations of the waters of their foraging zones. Many Mediterranean top-predatory fish still exceed European Union regulatory Hg thresholds. This emphasizes the necessity of monitoring the exposure of Mediterranean populations, to formulate adequate mitigation strategies and recommendations, without advising against seafood consumption. This review also points out other insufliciencies of knowledge of Hg cycling in the Mediterranean Sea, including temporal variations in air-sea exchange, hydrothermal and cold seep inputs, point sources, submarine groundwater discharge, and exchanges between margins and the open sea. Future assessment of global change impacts under the Minamata Convention Hg policy requires long-term observations and dedicated high-resolution Earth System Models for the Mediterranean region.
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Danciu, L., Weatherill, G., Rovida, A., Basili, R., Bard, P. - Y., Beauval, C., et al. (2022). The 2020 European Seismic Hazard Model: Milestones and Lessons Learned.
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Daval, D., Choblet, G., Sotin, C., & Guyot, F. (2022). Theoretical Considerations on the Characteristic Timescales of Hydrogen Generation by Serpentinization Reactions on Enceladus. Journal Of Geophysical Research-Planets, 127(2).
Résumé: The Cassini spacecraft demonstrated that Saturn's small moon Enceladus may harbor hydrothermal activity. In particular, molecular hydrogen production could result from water-rock interactions in a tidally heated, water-filled porous rocky core. The lifetime of such reactions is key to assess the habitability potential of Enceladus and to constrain plausible durations of the active stage in a context where the evolution of the moon is debated. Although it has recently been suggested that the serpentinization timescale does not exceed a few hundred million years, this estimation was based on assumptions regarding silicate dissolution kinetics that are prone to overestimate the actual reactivity of primary silicates. Here, we investigated plausible rate-limiting mechanisms governing fluid-rock interactions that could delay the completion of Enceladus' core serpentinization. In particular, we considered the impact of (a) various secondary mineral assemblages on the Gibbs free energy of Fe-bearing silicate dissolution and associated dissolution rates; (b) rate-laws alternative to the transition state theory; (c) diffusion in nanoporous secondary assemblages; (d) slow water supply. Overall, our results confirm that serpentinization timescales never exceed 500 Myr, and indicate that fluid flow ultimately sets the tempo for serpentinization. Only unreasonable grain sizes in Enceladus' core (>1 m) or unexpectedly low diffusivity of secondary coatings covering primary silicates would be consistent with serpentinization durations of several billion years. We thus suggest that either the hydrothermal activity has developed recently on Enceladus, or alternative processes (pyrolysis of insoluble organic matter, microbial activity) must be tested to explain the observed H-2 flux in Enceladus' plume.
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De Gelder, G., Doan, M. L., Beck, C., Carlut, J., Seibert, C., Feuillet, N., et al. (2022). Multi-scale and multi-parametric analysis of Late Quaternary event deposits within the active Corinth Rift (Greece). Sedimentology, 69(4), 1573–1598.
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de Gelder, G., Fernandez-Blanco, D., Ogretmen, N., Liakopoulos, S., Papanastassiou, D., Faranda, C., et al. (2022). Quaternary E-W Extension Uplifts Kythira Island and Segments the Hellenic Arc. Tectonics, 41(10).
Résumé: Several crustal and lithospheric mechanisms lead to deformation and vertical motion of the upper plate during subduction, but their relative contribution is often enigmatic. Multiple areas of the Hellenic Forearc have been uplifting since Plio-Quaternary times, yet spatiotemporal characteristics and sources of this uplift are poorly resolved. The remarkable geology and geomorphology of Kythira Island, in the southwestern Hellenic forearc, allow for a detailed tectonic reconstruction since the Late Miocene. We present a morphotectonic map of the island, together with new biostratigraphic dating and detailed analyses of active fault strikes and marine terraces. We find that the Tortonian-Pliocene stratigraphy in Kythira records similar to 100 m of subsidence, and a wide coastal rasa marks the similar to 2.8-2.4 Ma maximum transgression. Subsequent marine regression of similar to 300-400 m and minor E-W tilt are recorded in similar to 12 marine terrace levels for which we estimate uplift rates of similar to 0.2-0.4 mm/yr. Guided by simple landscape evolution models, we interpret the coastal morphology as the result of initial stability or of slow, gradual sea-level drop since similar to 2.8-2.4 Ma, followed by faster uplift since similar to 1.5-0.7 Ma. Our findings on- and offshore suggest that E-W extension is the dominant mode of regional active upper crustal deformation, and N-S normal faults accommodate most, if not all of the uplift on Kythira. We interpret the initiation of E-W extension as the result of a change in plate boundary conditions, in response to either propagation of the North Anatolian Fault, incipient collision with the African plate, mantle dynamics or a combination thereof.
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de Gelder, G., Husson, L., Pastier, A. - M., Fernandez-Blanco, D., Pico, T., Chauveau, D., et al. (2022). High interstadial sea levels over the past 420ka from the Huon Peninsula, Papua New Guinea. Communications Earth & Environment, 3(1).
Résumé: Global mean sea level curves based on oxygen isotope data underestimate interstadial sea level by as much as 20 m, according to coral reef terrace analysis and a reassessment of the regional deformation pattern at the Huon peninsula, Papua New Guinea The history of sea level across the Quaternary is essential for assessing past and future climate. Global sea-level reconstructions are typically derived from oxygen isotope curves, but require calibration with geological constraints that are scarce prior to the last glacial cycle (>130 thousand years ago). Here we show that the coral reef terrace sequence at the Huon Peninsula (Papua New Guinea) provides such constraints up to similar to 420 thousand years ago, through a geometric analysis of high-resolution topographic data. We derive a northward tectonic tilt as regional deformation pattern, and estimate relative sea level for 31 Quaternary periods, including several periods for which no relative sea level data exists elsewhere. Supported by numerical reef models, these estimates suggest that oxygen isotope-based global mean sea-level curves systematically underestimate interstadial sea-level elevations, by up to similar to 20 m. Compared to those curves, our results imply a stronger degree of non-linearity between ice-sheet volumes and global temperatures within Quaternary glacial cycles.
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De Plaen, R. S. M., Mordret, A., Arambula-Mendoza, R., Vargas-Bracamontes, D., Hugo Marquez-Ramirez, V., Lecocq, T., et al. (2022). The shallow three-dimensional structure of Volcan de Colima revealed by ambient seismic noise tomography. Journal Of Volcanology And Geothermal Research, 428.
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Delaere, C., & Guedron, S. (2022). The altitude of the depths: use of inland water archaeology for the reconstruction of inundated cultural landscapes in Lake Titicaca. World Archaeology, 54(1), 67–83.
Résumé: Andean societies have undergone abrupt climate changes that have affected their water resources and habitable or cultivable land. This is the case for Lake Titicaca, which has experienced fluctuations up to 20 metres during the last three millennia. Although paleoenvironmental reconstructions have provided valuable data on these lake level variations, their resolution is often not sufficient to assess their impact at the human time scale of land-use patterns. In this study, we provide a description of recent methodological developments in underwater archaeology that allows great advances in such reconstruction. Our results highlight that the level of the lake rose globally with multiple events of transgression and regression over the last two millennia. We also show that certain abrupt lake variation coincide with major transformations of the societies such as the emergence of the Tiwanaku state in the 6(th) century during a major transgression.
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Delgado, F., Zerathe, S., Schwartz, S., Mathieux, B., & Benavente, C. (2022). Inventory of large landslides along the Central Western Andes (ca. 15?-20? S): Landslide distribution patterns and insights on controlling factors. Journal Of South American Earth Sciences, 116.
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Doan, M. - L., Heap, M. J., Schell, M., & Kueppers, U. (2022). High strain rate damage in porous andesite. Journal Of Volcanology And Geothermal Research, 427.
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Dollet, C., & Gueguen, P. (2022). Global occurrence models for human and economic losses due to earthquakes (1967-2018) considering exposed GDP and population. Natural Hazards, 110(1), 349–372.
Résumé: In moderate-to-low seismic hazard regions, estimating the socio-economic consequences of an earthquake on the regional scale is a costly and difficult task. This study analyses existing global earthquake databases to build a loss flat file of 445 earthquakes since 1967 with a magnitude greater than 4.5. The flat file includes information on the social consequences (e.g. fatalities and injuries) and economic losses (e.g. direct and indirect costs, number of buildings destroyed or damaged). In this study, exposed population and GDP at the date of the earthquake complete the flat file information, estimated thanks to the exposed area computed with an empirical relationship derived from the ground motion footprint provided by USGS ShakeMap. Earthquake consequences have increased since 1967 and follow a non-stationary Poisson distribution with rate proportional to exposure. In order to assess the stationarity of the consequences, we assumed stationary losses and fatalities by normalizing consequences by the exposed wealth and population verified on a sub-set of earthquakes for which exact population is given by national census. The completeness of the flat file catalogue is compared to the international seismological catalogue, and we compute the annual rate of exceedance of human and direct economic losses relative to the exposed population and the associated GDP per capita. We show that, although the number of casualties and the absolute magnitude of losses increase as consequence of urban concentration, global losses, relative to effective exposure corresponding to macroseismic intensity of at least V, decrease. (Access to the flat file: https://www.isterre.fr/philippe-gueguen/earthquake-losses-database/).
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Dumont, T., Schwartz, S., Guillot, S., Malusa, M., Jouvent, M., Monie, P., et al. (2022). Cross-propagation of the western Alpine orogen from early to late deformation stages: Evidence from the Internal Zones and implications for restoration. Earth-Science Reviews, 232.
Résumé: The internal zones of the Western Alps arc are derived from an oceanic and continental subduction wedge developed beneath the Adria plate during its paleogene northward drift. Exhumation of the internal zones proceded from early Oligocene onwards due to westward extrusion of the Adria plate. The prominent fold-andthrust structures which follow the arc shape, either forward or backward verging, postdate the initial nappe stacking and overprint differently oriented older deformations which are relevant to proper retoration of this arcuate orogen to minimise overlap problems. We document this early stacking phase through outcrop-scale structural analysis at 55 sites between the Maurienne and Ubaye valleys, along with larger-scale examples of early structures. They consistently show an initial N- to NW tectonic transport, whose kinematic indicators are overprinted by either forward (W- to SW-directed) or backward (E- to NE-directed) deformation associated with post-nappe transport along the Penninic thrust. Accordingly, restoring the Brianconnais fold/thrust system must incorporate reconstruction of the nappe stack along the initial top N-NW direction of orogenic propagation, with careful consideration of their paleogeographic origin towards the S-SE. This stack was built during the Eocene Adria-Iberia collision, and overthrust the Subbrianconnais-Valaisan trough to the NW before involving the Dauphine '-Helvetic foreland. It includes different types of Paleozoic units, either Permo-Carboniferous sediments towards its base, or polymetamorphic basement above, which can be explained by inversion of a late Variscan basin and of its southern shoulder, whereas the uppermost Prepiedmont units result from inversion of the Tethyan margin toe. Mixed breccia, locally preserved close to the tectonic contact between the latter units and the overlying “Schistes Lustre ' s” oceanic nappes, are interpreted as olistostromes fed by both units in a very early collision stage. 39Ar/40Ar dating suggests that these shallow tectono-sedimentary formations were involved in the subduction wedge during the early Eocene, whereas younger (late Eocene) equivalent olistostromes mark the propagation of the Brianconnais stack over the external (Dauphine '/Helvetic) foreland. The Eocene orogenic wedge was rapidly exhumed during Oligocene westward indentation and radial spreading, in a markedly different tectonic context driven by extrusion around an Adriatic upper mantle indenter, which controlled development of the Western Alps arc in relation with the Ligurian sea opening.
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Dusseaux, C., Gebelin, A., Boulvais, P., Ruffet, G., Poujol, M., Cogne, N., et al. (2022). Timing and duration of meteoric water infiltration in the Quiberon detachment zone (Armorican Massif, Variscan belt, France). Journal Of Structural Geology, 156.
Résumé: Assessing the geochemical signature and the role of fluids in a key Variscan detachment zone demonstrates the link between crustal deformation, thermo-mechanical events and Variscan mineralization. We document meteoric fluid infiltration into the ductile segment of the Late-Carboniferous Quiberon detachment zone (QDZ), when synkinematic muscovite and tourmaline crystallized and equilibrated with deuterium-depleted surface-derived fluids during high-temperature deformation. Titanium-in-muscovite thermometry supported by microstructures indicate that syntectonic isotope exchange between fluids and hydrous minerals occurred above 500 degrees C. 40Ar/39Ar muscovite data (similar to 319-similar to 303 Ma) and U(-Th)/Pb geochronology on zircon, monazite and apatite (similar to 318-similar to 305 Ma) from syntectonic leucogranites together with microstructural and geochemical (U and REE contents) data suggest that meteoric fluid-rock-deformation interaction started at similar to 320 Ma and played a major role in leaching uranium at similar to 305 Ma. U-Th/Pb data (similar to 330-similar to 290 Ma) from migmatites located below the QDZ strengthen the idea that meteoric fluid infiltration, detachment activity, syntectonic leucogranite emplacement and migmatization were coeval and allowed the development of a sustained hydrothermal system.
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Dussert, F., Sarret, G., Wegner, K. D., Proux, O., Landrot, G., Jouneau, P. - H., et al. (2022). Physico-Chemical Transformation and Toxicity of Multi-Shell InP Quantum Dots under Simulated Sunlight Irradiation, in an Environmentally Realistic Scenario. Nanomaterials, 12(20).
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Edmund, E., Morard, G., Baron, M. A., Rivoldini, A., Yokoo, S., Boccato, S., et al. (2022). The Fe-FeSi phase diagram at Mercury's core conditions. Nature Communications, 13(1).
Résumé: The iron-silicon phase diagram has been established at the conditions of Mercury's core. The resulting phase diagram is remarkably complex, and presents an array of new mechanisms which may power Mercury's inner dynamo. Mercury's metallic core is expected to have formed under highly reducing conditions, resulting in the presence of significant quantities of silicon alloyed to iron. Here we present the phase diagram of the Fe-FeSi system, reconstructed from in situ X-ray diffraction measurements at pressure and temperature conditions spanning over those expected for Mercury's core, and ex situ chemical analysis of recovered samples. Under high pressure, we do not observe a miscibility gap between the cubic fcc and B2 structures, but rather the formation of a re-entrant bcc phase at temperatures close to melting. Upon melting, the investigated alloys are observed to evolve towards two distinct Fe-rich and Fe-poor liquid compositions at pressures below 35-38 GPa. The evolution of the phase diagram with pressure and temperature prescribes a range of possible core crystallization regimes, with strong dependence on the Si abundance of the core.
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Eijsink, A. M., Kirkpatrick, J. D., Renard, F., & Ikari, M. J. (2022). Fault surface morphology as an indicator for earthquake nucleation potential. Geology, 50(12), 1356–1360.
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Espin Bedon, P. A., Audin, L., Doin, M. - P., Pinel, V., Pathier, E., Mothes, P., et al. (2022). Unrest at Cayambe Volcano revealed by SAR imagery and seismic activity after the Pedernales subduction earthquake, Ecuador (2016). Journal Of Volcanology And Geothermal Research, 428.
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Essing, D., & Poli, P. (2022). Spatiotemporal Evolution of the Seismicity in the Alto Tiberina Fault System Revealed by a High-Resolution Template Matching Catalog. Journal Of Geophysical Research-Solid Earth, 127(10).
Résumé: The Alto Tiberina Fault system, located in the Northern Apennines (Italy), consists of a low angle normal fault (LANF) which radiates micro-seismicity that can be explained by continuous creep. On top of the LANF, a network of syn- and antithetic high angle faults frequently hosts seismic swarms, one of which has been associated with a transient aseismic deformation signal. To study in detail the seismicity and its relationships with aseismic deformation processes occurring in this fault system, we apply template matching on seismic data recorded at an array of borehole stations, to derive a high-resolution earthquake catalog. Thanks to the additionally detected events, we are able to reveal time periods of increased spatial- and temporal clustering during an aseismic deformation event. This reflects the complex evolution of aseismic slip together with the complexity of the shallow fault system. Along the LANF, we observe a bimodal type of seismicity, with diffuse seismicity active continuously, and short-lived bursts of seismicity that could indicate rapid fluid releases. We additionally identify repeating earthquakes. These events not necessarily match a simple creep model and therefore open the possibility for new models to explain the seismicity along the LANF.
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Feitshans, I. L., & Sabatier, P. (2022). Global health impacts of nanotechnology law: Advances in safernano regulation (Vol. 67).
Résumé: Nanoregulation is a dynamic process worldwide. This article begins with a short overview of legislative antecedents for emerging laws about nanotechnology, then examines key trends in emerging nanoregu-lations that govern global commercialization of nanomaterials. Around the world, hundreds of emerging laws have begun to sprout like mushrooms in unexpected places all over the globe. Surrounding these mushrooms is a treacherous swamp of new law, draft laws and pre-existing laws. Although guidelines based on expertise can sometimes serve as powerful influencers of opinion and may determine subse-quent course of actions, such pronouncements lack the legitimate power of statutory law. This article begins with a short overview of legislative antecedents for emerging laws and guidelines about nanotech-nology, then examines key trends in emerging nanoregulations that govern global commercialization of nanomaterials. Science and law can partner to minimize risk while maximizing societal benefit; research scientists and others can participate proactively in that legislative process.Copyright (c) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Confer-ences & Exhibition on Nanotechnologies, Organic Electronics & Nanomedicine – NANOTEXNOLOGY 2021.
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Fernandes, R., Bruyninx, C., Crocker, P., Menut, J. - L., Socquet, A., Vergnolle, M., et al. (2022). A new European service to share GNSS Data and Products. Annals Of Geophysics, 65(3).
Résumé: This paper describes the new GNSS data and product services that have been developed within the context of the EPOS (European Plate Observing System) European Research Infrastructure Consortium (ERIC), which is part of the European Strategy Forum on Research Infrastructures. These services, optimized for Solid Earth research applications, endeavour to harmonise, and standardise Global Navigation Satellite System (GNSS) data collection and processing. They have been implemented by the members of the GNSS Data & Products (EPOS-GNSS), one of the Thematic Core Services (TCS) of EPOS with the active support of national and pan-European infrastructures (in particular the Regional Reference Frame Sub-Commission for Europe (EUREF) of the International Association of Geodesy). The optimized use of data from dozens of diverse European GNSS networks, installed not specifically for geodynamic studies, created additional requirements from an organizational and technical point of view, the solutions for which we describe in this article. The data flows from data suppliers and analysis centers to the various TCS Data & Product Portals are described, as well as their integration into the overall EPOS system. This is made through GLASS (GNSS Linkage Advanced Software System), a dedicated software package developed since 2016, whose architecture and functionalities are detailed here. Time series and other GNSS products computed at the several analysis centers are described as are the quality control steps that are performed. Finally, several user cases are presented that demonstrate how different stakeholders (from data providers to scientists) can benefit from the efforts being carried out by the EPOS-GNSS community.
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Fiolleau, S., Jongmans, D., Bievre, G., Chambon, G., Michel, O., & Borgniet, L. (2022). Study of clay degradation in an earthslide combining OBIA and roughness analysis of UAV-based optical images. Earth Surface Processes And Landforms, 47(15), 3465–3480.
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Ford, M., Masini, E., Verges, J., Pik, R., Ternois, S., Leger, J., et al. (2022). Evolution of a low convergence collisional orogen: a review of Pyrenean orogenesis. Bsgf-Earth Sciences Bulletin, 193.
Résumé: The Pyrenees is a collisional orogen built by inversion of an immature rift system during convergence of the Iberian and European plates from Late Cretaceous to late Cenozoic. The full mountain belt consists of the pro-foreland southern Pyrenees and the retro-foreland northern Pyrenees, where the inverted lower Cretaceous rift system is mainly preserved. Due to low overall convergence and absence of oceanic subduction, this orogen preserves one of the best geological records of early orogenesis, the transition from early convergence to main collision and the transition from collision to post-convergence. During these transitional periods major changes in orogen behavior reflect evolving lithospheric processes and tectonic drivers. Contributions by the OROGEN project have shed new light on these critical periods, on the evolution of the orogen as a whole, and in particular on the early convergence stage. By integrating results of OROGEN with those of other recent collaborative projects in the Pyrenean domain (e.g., PYRAMID, PYROPE, RGF-Pyrenees), this paper offers a synthesis of current knowledge and debate on the evolution of this immature orogen as recorded in the synorogenic basins and fold and thrust belts of both the upper European and lower Iberian plates. Expanding insight on the role of salt tectonics at local to regional scales is summarised and discussed. Uncertainties involved in data compilation across a whole orogen using different datasets are discussed, for example for deriving shortening values and distribution.
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Garnier, J., & Roux, P. (2022). Modal formulation and paraxial approximation for acoustic wave propagation in waveguides with surface perturbations. Journal Of The Acoustical Society Of America, 151(5), 3239–3254.
Résumé: We propose a modal approach developed in the framework of the paraxial approximation to investigate the effects of deterministic surface perturbations in a planar waveguide. In the first part, the sensitivity of the modal amplitudes is theoretically formulated for a three-dimensional perturbation at the air-water interface. When applied to a broadband ultrasonic signal in a laboratory tank experiment, this approach results in travel-time and amplitude fluctuations that are successfully compared to experimental data recorded between two vertical source-receiver arrays that span the ultrasonic waveguide. The nonlinear shape of the modal amplitude fluctuations is of particular interest and is due to the three-dimensional nature of the surface perturbation. In the second part, a time-harmonic inversion method is built in the paraxial single-scattering approximation to image the dynamic surface perturbation from the modal transmission matrix between two source-receiver arrays. Again, the inversion results for capillary-gravity surface perturbations are successfully compared to similar inversions performed from experimental data processed with a complete set of eigenbeams extracted between the two arrays. (c) 2022 Acoustical Society of America.
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Gautheron, C., Hueck, M., Ternois, S., Heller, B., Schwartz, S., Sarda, P., et al. (2022). Investigating the Shallow to Mid-Depth (> 100-300 degrees C) Continental Crust Evolution with (U-Th)/He Thermochronology: A Review. Minerals, 12(5).
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Gautheron, C., Sawakuchi, A. O., dos Santos Albuquerque, M. F., Cabriolu, C., Parra, M., Ribas, C. C., et al. (2022). Cenozoic weathering of fluvial terraces and emergence of biogeographic boundaries in Central Amazonia. Global And Planetary Change, 212.
Résumé: The study of paleofluvial dynamics is crucial to understand the role of rivers as biogeographic boundaries in Amazonia during the Cenozoic. In central Amazonia, Mesozoic and Cenozoic fluvial deposits -Alter do Chao, Iranduba and Novo Remanso Formations-host supergene iron oxides and record changes in the distribution of flooded and non-flooded (upland) environments. Geochronological data on these deposits are still scarce to constrain past landscape changes. Therefore, in this study we investigate iron oxides precipitated within weathering profiles developed on ancient fluvial terraces to access the interplay between flooded and non-flooded environments in central Amazonia. We aimed to trace the history of abandonment of alluvial plains and the subsequent weathering of lowland sediment deposits during the Cenozoic. We identified at least two main periods of iron oxide precipitation: (1) one starting before similar to 42 Ma and ending at similar to 18 Ma; and (2) a well-defined humid and weathering prone phase between-8 and 1 Ma. Dominant goethite precipitation marks a major climatic shift towards more humid conditions from similar to 3 Ma. The increase in water discharge of the Negro and Solimoes rivers possibly promoted fluvial incision and conversion of floodplains into long-lasting upland terrains as indicated by the development of lateritic weathering profiles. This major phase of upland expansion corroborates upland birds phylogenetic data, which indicate the emergence of a major biogeographic barrier in central Amazonia during late Pliocene/Pleistocene.
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Gerard, B., Robert, X., Audin, L., Gautheron, C., & Bernet, M. (2022). First Apatite (U-Th)/He and apatite fission-track thermochronology dataset from the Abancay Deflection (Eastern Cordillera, Southern Peru). Data In Brief, 40.
Résumé: According to their respective temperature sensitivities, Apatite (U-Th)/He (AHe) and apatite fission-track (AFT) thermochronology records the thermal evolution of the upper crust (<5 km) and is a key for distinguishing between different exhumation mechanisms through time-evolving rock uplift, and landscape evolution. We applied these methods to extract the thermal evolution of the upper crust in the Abancay Deflection at the northern edge of the Altiplano (southern Peru). We present 120 single-crystal AHe ages (from 31 samples) and 27 AFT central ages obtained from magmatic bodies across the study area. AHe ages range from 0.6 +/- 0.1 to 35.8 +/- 2.9 Ma with a satisfactory reproducibility of single-crystal AHe ages with less than 10% averaged dispersion. AFT ages range from 2.6 +/- 1.9 to 38.2 +/- 4.4 Ma with P(chi(2)) values >5%. This dataset allows exploring the crust evolution from the late-Eocene to the Quaternary. Data processed and interpreted in the related article published in Tectonics [6] are stored in PANGAEA repository (108 AHe single-grain ages and 27 AFT ages). We furthermore present in this article 12 extra single-grain AHe ages obtained after the related article publication. We also present the details of fission-track length measurements published in the related article. Thermochronological ages could be reused for testing He diffusion or fission track annealing processes or investigating the broader tectonic/geodynamic evolution of the Andes. (C) 2021 The Author(s). Published by Elsevier Inc.
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Gerard, B., Robert, X., Grujic, D., Gautheron, C., Audin, L., Bernet, M., et al. (2022). Zircon (U-Th)/He Closure Temperature Lower Than Apatite Thermochronometric Systems: Reconciliation of a Paradox. Minerals, 12(2).
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Gerbault, M., Fontaine, F. J., Peltier, A., Got, J. - L., Hassani, R., Ferrazzini, V., et al. (2022). What causes the persistent seismicity below the eastern flank of Piton de la Fournaise (la R?eunion Island)? Elasto-plastic models of magma inflation. Journal Of Volcanology And Geothermal Research, 431.
Résumé: Identifying the causes of flank destabilization of active volcanic edifices is key to prevent catastrophic events. The persistent seismicity recorded below the eastern flank of Piton de la Fournaise shield volcano (la Re ' union Island), both in between and during eruptive events, may give indications on the mechanical stability of this edifice. Whether this asymmetric “cup” shaped seismicity is linked to magma injections and whether it sparks a gravitational flank slide motivates this study. Here we model the elasto-plastic behavior of this volcanic edifice at crustal scale, with the 3D finite-element code Adeli. First, we test the influence of tensile failure, recently implemented in combination to a Drucker-Prager shear failure criterion; a pressurized cavity below a flat top surface triggers shear failure in general, with tensile failure restricted to the surface and cavity tip. Then we include the topography of Piton de la Fournaise in the gravity field. Considering first only elasticity, deviatoric stresses attain about 35 MPa below the volcanic edifice and displacements are maximum in the horizontal east-west direction, reaching 30 m near sea-level. Introducing plastic behavior produces a rather symmetric cup shape plastic domain around the volcano's summit, that extends at depth with reducing bedrock effective friction (which acts is a proxy for reduced standard friction due to pore fluid pressurization). An asymmetric listric shear zone develops down to -3 km (bsl) only if the tensile strength, cohesion and friction angle are set as low as 1.5 MPa, 3 MPa and 3 degrees, respectively; these values hence provide a lower bound for the edifice's effective strength. The second part of this study explores the influence of an internal overpressure, which is either applied as a vertical inflation source located about 500 m below the surface of the eastern flank, simulating a distal dike, or from a deeper ellipsoid simulating the magma reservoir located at depth ca. 0 km (near sea level) below the summit. The resulting strain pattern forms a cup-shaped shear zone dipping down below the eastern flanks of the edifice, reaching depth -2 km (bsl) if effective friction angle is <= 5 degrees. Whereas the deep base of the dike and the eastern edge of the magma reservoir coincide geometrically in the models, the inflating dike produces a shear zone 1 km shallower than does the inflating magma reservoir, the latter coinciding better with the shape of the observed seismic cup. Hence, we propose that this structure is a mechanical consequence of continuous magma supply in the reservoir, coherent with previous interpretations. This means that at least originally it did not need to form as a pre-existing weak zone or a magma-filled structure. However, this shear zone delimits an underlying domain in dilatation relative to a constricted hanging-wall; it may thus promote magma sills. It also branches to the surface with planar radial shear zones comparable to some observed eruptive fissures. The 3D kinematics of this shear zone does not rule out the possibility of a giant flank slide, although it does not appear today as imminent.
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Ghimire, S., Gueguen, P., Giffard-Roisin, S., & Schorlemmer, D. (2022). Testing machine learning models for seismic damage prediction at a regional scale using building-damage dataset compiled after the 2015 Gorkha Nepal earthquake. Earthquake Spectra, 38(4), 2970–2993.
Résumé: Assessing post-seismic damage on an urban/regional scale remains relatively difficult owing to the significant amount of time and resources required to acquire information and conduct a building-by-building seismic damage assessment. However, the application of new methods based on artificial intelligence, combined with the increasingly systematic availability of field surveys of post-seismic damage, has provided new perspectives for urban/regional seismic damage assessment. This study analyzes the effectiveness and relevance of a number of machine learning techniques for analyzing spatially distributed seismic damage after an earthquake at the regional scale. The basic structural parameters of a portfolio of buildings and the post-earthquake damage surveyed after the Nepal 2015 earthquake are analyzed and combined with macro-seismic intensity values provided by the United States Geological Survey ShakeMap tool. Among the methods considered, the random forest regression model provides the best damage predictions for specified ground motion intensity values and structural parameters. For traffic-light-based damage classification (three classes: green-, amber-, and red-tagged buildings based on post-earthquake damage grade), a mean accuracy of 0.68 is obtained. This study shows that restricting learning to basic features of buildings (i.e. number of stories, height, plinth area, and age), which could be readily available from authoritative databases (e.g. national census) or field-surveyed databases, yields a reliable prediction of building damage (4 features/3 damage grade accuracy: 0.64).
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Giammarinaro, B., Tsarsitalidou, C., Hillers, G., de Rosny, J., Seydoux, L., Catheline, S., et al. (2022). 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, F., Viveiros, F., Silva, C., Thapa, S., Pacheco, J. E., Adhikari, L. B., et al. (2022). Radon signature of CO2 flux constrains the depth of degassing: Furnas volcano (Azores, Portugal) versus Syabru-Bensi (Nepal Himalayas). Scientific Reports, 12(1).
Résumé: Substantial terrestrial gas emissions, such as carbon dioxide (CO2), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO2 and radon-222 fluxes at the surface constrains the depth of degassing at two hydrothermal systems in geodynamically active contexts: Furnas Lake Fumarolic Field (FLFF, Azores, Portugal) with mantellic and volcano-magmatic CO2, and Syabru-Bensi Hydrothermal System (SBHS, Central Nepal) with metamorphic CO2. At both sites, radon fluxes reach exceptionally high values (> 10 Bq m(-2) s(-1)) systematically associated with large CO2 fluxes (> 10 kg m(-2) day(-1)). The significant radon-CO2 fluxes correlation is well reproduced by an advective-diffusive model of radon transport, constrained by a thorough characterisation of radon sources. Estimates of degassing depth, 2580 +/- 180 m at FLFF and 380 +/- 20 m at SBHS, are compatible with known structures of both systems. Our approach demonstrates that radon-CO2 coupling is a powerful tool to ascertain gas sources and monitor active sites. The exceptionally high radon discharge from FLFF during quiescence (approximate to 9 GBq day(-1)) suggests significant radon output from volcanoes worldwide, potentially affecting atmosphere ionisation and climate.
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Girault, J. B., Bellahsen, N., Bernet, M., Pik, R., Loget, N., Lasseur, E., et al. (2022). Exhumation of the Western Alpine collisional wedge: New thermochronological data. Tectonophysics, 822.
Résumé: Collisional shortening in the external Western Alps was first accommodated by internal (distributed) deformation in the External Crystalline Massifs (ECM) and then on frontal crustal ramps (localized deformation). However, the timing of transition between these two periods is still under-constrained, mainly because the available dataset is incomplete in the Western Alps. We here provide new zircon and apatite fission-track (ZFT and AFT) and zircon (U-Th-Sm)/He (ZHe) data that constrain the early stages of cooling hence exhumation of the external Alpine wedge, as well as new Raman Spectroscopy of Carbonaceous Material (RSCM) data from the Belledonne massif. ZFT ages mainly range between 15 and 20 Ma, ZHe ages between 5 and 12 Ma, AFT ages between 2 and 10 Ma. Those data are integrated within inverse and forward thermal history modelling (HeFTy) along with literature data to constrain the late Oligocene-Miocene cooling history and suggest that exhumation of the Belledonne and the Pelvoux massifs may have started as early as ca. 27 Ma. This early exhumation was rather slow (similar to 50 m.Myrs(-1) +/- 2 m.Myrs(-1)) and may date the transition between the distributed and the localized mode of shortening, i.e., the initiation of the crustal ramps below these massifs. Further north, in the Mont Blanc and Aiguilles Rouges massifs, exhumation was active around 18 Ma, and started possibly earlier, around 20-25 Ma. From this time on (18 Ma), exhumation rates increased in all external massifs (similar to 500 +/- 40 m.Myrs(-1), both North and South). This age most likely corresponds to the end of the transition period between distributed and localized shortening with localisation along the frontal crustal ramps and the rapid associated exhumation, then cooling of the hangingwall (even considering that cooling may start a few Myrs later than exhumation if isoterms are advected). This timing notably corresponds to a transition between the two molasse mega-sequences in the foreland basin (Lower Marine/Freshwater Molasse and Upper Marine/Freshwater Molasse).
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Gomez-Romeu, J., Kusznir, N., Ducoux, M., Jammes, S., Ball, P., Calassou, S., et al. (2022). Formation of SDRs-Ocean transition at magma-rich rifted margins: Significance of a mantle seismic reflector at the western Demerara margin. Tectonophysics, 845.
Résumé: At distal magma-rich rifted margins, seismic reflections several seconds below the-10 s TWT expected base of petrological crust for thermally equilibrated lithosphere, are commonly observed. These deep seismic reflectors are often interpreted as the petrological Moho as they distally rise and merge into the imaged oceanic Moho, however, the origin of these deep seismic reflections beneath the expected base of the petrological crust is not understood. We investigate the example of the Jurassic Demerara Plateau located offshore north-east South America, which shows a strong seismic reflection at-15 s TWT, beneath 20 km thick SDRs (Seaward Dipping Reflectors). We use combined inversion of gravity and seismic reflection data, together with seismic interpretation, to investigate the depth of the deep reflector, its origin, formation as well as the composition and structure of the overlying material. Results from quantitative techniques show that the deep reflector is located below the SDRs at least 10 km within the mantle at a depth of-42 km. These results, together with seismic interpretation, suggest that the deep reflector corresponds to an intra-mantle detachment limiting semi-ductile and sheared magmatic-infiltrated mantle above from depleted ductile asthenospheric mantle below. Distally, the semi-ductile mantle is removed when the asthenospheric mantle focuses to form a stable mid-oceanic ridge. This lateral evolution results from a progressive coupling between the magmatic SDRs above and the asthenospheric mantle below. Therefore, we propose that the intra-mantle detachment, corresponding to a rheological contrast, plays a key role in the transition from distributed lithosphere extension to focused mid-ocean ridge accretion at distal magma-rich rifted margins. In addition, it may represent an indicator to determine the thermal structure of a magma-rich rifted margin.
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Goodenough, K. M., Deady, E. A., Beard, C. D., Broom-Fendley, S., Elliott, H. A. L., van den Berg, F., et al. (2022). Carbonatites and Alkaline Igneous Rocks in Post-Collisional Settings: Storehouses of Rare Earth Elements (vol 32, pg 1332, 2021). Journal Of Earth Science, 33(4), I-I.
Résumé: This article was originally published electronically on the publisher's internet portal on 23 August 2021. With the author(s)' decision, the copyright of the article changed on 27 of January 2022 to (c) British Geological Survey, UKRI 2022 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit . The original article has been corrected
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Gosselin, J. M., Dosso, S. E., Askan, A., Wathelet, M., Savvaidis, A., & Cassidy, J. F. (2022). A review of inverse methods in seismic site characterization. Journal Of Seismology, 26(4), 781–821.
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Grendas, I., Theodoulidis, N., Bard, P. - Y., Perron, V., Hatzidimitriou, P., & Hollender, F. (2022). Can site effects be estimated with respect to a distant reference station? Performance of the spectral factorization of coda waves. Geophysical Journal International, 230(1), 1–28.
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Grendas, I., Theodoulidis, N., Hollender, F., & Hatzidimitriou, P. (2022). Spectral decomposition of S-waves in investigating regional dependent attenuation and improving site amplification factors: A case study in western Greece. Bulletin Of Earthquake Engineering, 20(12), 6441–6465.
Résumé: Seismic-hazard analysis is based on the knowledge of the factors that configure the wave attenuation properties due to the loss of energy radiated away from the source (geometrical spreading and anelastic attenuation) and the site amplification due to surface geological conditions (the so-called site effects). Both factors can be separately investigated based on Generalized Inversion Techniques (GIT), through spectral decomposition of earthquake recordings in terms of Fourier Amplitude Spectra (FAS). In this study a parametric GIT algorithm, was applied in western Greece, allowing a simultaneous spectral decomposition of S-wave records in order to estimate parameters controlling seismic motion. The analyses provided a regional variation of the quality factor, Q(s) between 23-91, with a geometric mean value of 45, a distance dependent geometrical spreading attenuation factor gamma, gamma, smoothly decreased between 12 and 200 km, from 0.98 to 0.77, as well as Site Amplification Factors for both horizontal and vertical components of 24 sites located in the study area. Moment Magnitudes, M-w and corner frequencies, f(c), were computed for the examined earthquakes, indicating an increasing trend of stress drop, Delta sigma from similar to 6 to similar to 55 bar for M-w = 2.5 to 5.2. The estimated values of these parameters, are in good agreement with the corresponding ones based on other methodologies, concluding to the relevant low average logarithmic misfit (similar to 0.17) between observed and synthetic FAS. Consequently, attenuation and site amplification factors computed in this study, can provide rational input parameters for stochastic S-wave simulations, improving thus deterministic seismic hazard assessment.
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Gudmundsson, A., Drymoni, K., Browning, J., Acocella, V., Amelung, F., Bonali, F. L., et al. (2022). Volcanotectonics: the tectonics and physics of volcanoes and their eruption mechanics. Bulletin Of Volcanology, 84(8).
Résumé: The physical processes that operate within, and beneath, a volcano control the frequency, duration, location and size of volcanic eruptions. Volcanotectonics focuses on such processes, combining techniques, data, and ideas from structural geology, tectonics, volcano deformation, physical volcanology, seismology, petrology, rock and fracture mechanics and classical physics. A central aim of volcanotectonics is to provide sufficient understanding of the internal processes in volcanoes so that, when combined with monitoring data, reliable forecasting of eruptions, vertical (caldera) and lateral (landslide) collapses and related events becomes possible. To gain such an understanding requires knowledge of the material properties of the magma and the crustal rocks, as well as the associated stress fields, and their evolution. The local stress field depends on the properties of the layers that constitute the volcano and, in particular, the geometric development of its shallow magma chamber. During this decade an increasing use of data from InSAR, pixel offset and structure-from-motion, as well as dense, portable seismic networks will provide further details on the mechanisms of volcanic unrest, magma-chamber rupture, the propagation of magma-filled fractures (dikes, inclined sheets and sills) and lateral and vertical collapse. Additionally, more use will be made of accurate quantitative data from fossil and active volcanoes, combined with realistic numerical, analytical and machine-learning studies, so as to provide reliable models on volcano behaviour and eruption forecasting.
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Guillemot, A., Baillet, L., Larose, E., & Bottelin, P. (2022). Changes in resonance frequency of rock columns due to thermoelastic effects on a daily scale: observations, modelling and insights to improve monitoring systems. Geophysical Journal International, 231(2), 894–906.
Résumé: Slope instabilities, including prone-to-fall rock columns, are known to exhibit clear vibrational modes. The resonance frequencies of these modes can be tracked by seismic instrumentation, allowing the rock column's mechanical and structural properties to be monitored, as well as providing precursors of imminent irreversible failures. In previous studies, superficial thermoelastic effects were assumed to drive daily fluctuations in resonance frequencies, but no qualitative or quantitative evidence was provided. The results presented here corroborate this hypothesis and quantify the physical processes involved. We interpreted daily variations of resonance frequencies in the Les Arches study site (Vercors, French Prealps) using a thermo-mechanical finite-element model. Modelled fluctuations of the resonance frequencies over a day closely matched experimental observations, reproducing the daytime frequency increase of around 2 per cent. In addition, our model provides explanation of the various behaviours observed across study sites: the frequency response strongly depends on solar exposure, as well as the timing and intensity of both radiative and convective heat fluxes. We highlight acousto-elastic constants as key parameters of our semi-quantitative model, although they remain poorly constrained here. For future instrumentation, we therefore recommend the deployment of pyranometers on rocky sites to accurately invert these parameters over time, thus allowing rock fracturing to be quantitatively tracked by acousto-elastic monitoring.
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Guillon, H., Mugnier, J. - L., Schwing, A., & Buoncristiani, J. - F. (2022). Glacial drainage development controls temporal and spatial fluctuations of sediment flux in Mont Blanc's North face. Comptes Rendus Geoscience, 354, 281–301.
Résumé: Present-day global warming raises important issues regarding sediment flux from glaciated catchments. The detrital export from such environments results from erosion processes operating in three geomorphic domains: the supraglacial rockwalls, the ice-covered substratum and the proglacial area, downstream from the glacier. The dominant process controlling present-day sediment export from glaciated catchments remains debated with most studies underlining the paraglacial dynamics in the glacier forefront. This study nuances these observations by quantifying the contribution from each geomorphic domain to the export of a glaciated catchment in the North face of Mont-Blanc (France). High resolution hydro-sedimentary flux data were acquired during eight years in two proglacial streams with contrasting glacio-hydrological characteristics, Bossons and Crosette streams. In the Bossons stream catchment, the sediment response highlights the initiation of the dendritic drainage network beneath the glacier, the short-lived evacuation of an annual storage during the early melt-season and its subsequent steadier regime. In addition, three years exhibit late melt season exports which are uncorrelated with temperature or rainfall. The evolution of the drainage network throughout the melt season explains the evacuation of the annual and pluri-annual subglacial sediment stocks. In addition, glacial retreat in link with higher melt rate allows for exporting a pluriannual sediment stock stored beneath the glacier. To conclude, the present-day sediment response in Bossons catchment displays distinct components with characteristic timescales and is dampened by intermediate storage controlled by drainage development and extreme events in the glacial and proglacial domains.
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Guren, M. G., Sveinsson, H. A., Malthe-Sorenssen, A., & Renard, F. (2022). Nanoscale Damage Production by Dynamic Tensile Rupture in alpha-Quartz. Geophysical Research Letters, 49(20).
Résumé: The creation of new fractures during an earthquake produces rock damage and contributes to the dissipation of strain energy. During dynamic rupture propagation, tensile microfractures can form in the earthquake process zone and in the domains around a fault that host large transient tensile stress. These microfractures can produce rock fragments with a wide range of sizes. Using molecular dynamics simulations, we model tensile rupture propagation in alpha-quartz under conditions of stress that occur during earthquake propagation. Our results show that for rupture speeds below 15% of the Rayleigh wave speed, fractures propagate linearly. At higher speeds, fracture propagation undergoes path instabilities with crack oscillations and microbranching leading to the formation of nanoscale roughness and fragments. This nanoscale damage can form in and around the earthquake process zone before any significant slip has occurred on the fault. The produced nanoparticles may control further energy dissipation during frictional slip.
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Harrichhausen, N., Morell, K. D., Regalla, C., Lynch, E. M., & Leonard, L. J. (2022). Eocene Terrane Accretion in Northern Cascadia Recorded by Brittle Left-Lateral Slip on the San Juan Fault. Tectonics, 41(10).
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Hendrickx, H., Le Roy, G., Helmstetter, A., Pointner, E., Larose, E., Braillard, L., et al. (2022). Timing, volume and precursory indicators of rock- and cliff fall on a permafrost mountain ridge (Mattertal, Switzerland). Earth Surface Processes And Landforms, 47(6), 1532–1549.
Résumé: High mountain environments are increasingly affected by rockfall-related hazards, driven by climate change. Studying rockfall in these environments is, however, challenging due to the inaccessibility of mountain ridges and the complex interaction between controlling factors. In this study, the rock wall of Grosse Grabe North Pillar in the Matter valley (Western Swiss Alps) was studied in detail over a timespan of 4 years (2017-2021). Data was collected from time-lapse photography, terrestrial laser scanning, unmanned aerial vehicle photogrammetry and seismic measurements. The presented dataset is unique because data collection started before the onset of the rock wall destabilization, allowing us to understand precursory indicators of large-scale events. In total, we recorded 382 rock- and cliff fall events (100-31 300 m(3)), with a total volume of 204 323 +/- 8173 m(3), resulting in a scar depth of similar to 40 m. An associated rock wall retreat rate of 71.2 +/- 2.8 mm year(-1) was calculated for the 1991-2021 period. Highly fractured south-exposed gneiss lithology is viewed as the main predisposition for the observed rock- and cliff fall events, allowing high-temperature oscillations to cause irreversible movements at fracture level. Cliff falls (10(4)-10(6) m(3)) were preluded by an outward movement of the rock wall that started to increase 1.5 years before any significant collapse of the rock wall, reaching locally up to 30 cm. All cliff fall events occurred in summer, exposing ice in the clefts. This is assumed to be the base of the permafrost from the north side. Rapid permafrost degradation is viewed as a triggering factor after its exposure, causing progressive failure of the rock wall, leading to very high rock wall retreat rates on a decadal timescale.
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Henneron, L., Balesdent, J., Alvarez, G., Barre, P., Baudin, F., Basile-Doelsch, I., et al. (2022). Bioenergetic control of soil carbon dynamics across depth. Nature communications, 13(1), 7676.
Résumé: Soil carbon dynamics is strongly controlled by depth globally, with increasingly slow dynamics found at depth. The mechanistic basis remains however controversial, limiting our ability to predict carbon cycle-climate feedbacks. Here we combine radiocarbon and thermal analyses with long-term incubations in absence/presence of continuously 13C/14C-labelled plants to show that bioenergetic constraints of decomposers consistently drive the depth-dependency of soil carbon dynamics over a range of mineral reactivity contexts. The slow dynamics of subsoil carbon is tightly related to both its low energy density and high activation energy of decomposition, leading to an unfavourable 'return-on-energy-investment' for decomposers. We also observe strong acceleration of millennia-old subsoil carbon decomposition induced by roots ('rhizosphere priming'), showing that sufficient supply of energy by roots is able to alleviate the strong energy limitation of decomposition. These findings demonstrate that subsoil carbon persistence results from its poor energy quality together with the lack of energy supply by roots due to their low density at depth.
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Hentschel, F., Janots, E., Magnin, V., Brueckner, L. M., & Trepmann, C. A. (2022). Transient deformation and long-term tectonic activity in the Eastern Alps recorded by mylonitic pegmatites. Journal Of Structural Geology, 155.
Résumé: Mylonitic pegmatites from the Austroalpine basement north of the Deferregen-Antholz-Vals shear zone (DAV) in the Eastern Alps record episodic deformation at greenschist facies conditions after the Eoalpine tectonometamorphic event and before uplift in the Oligocene. Fluorapatite-allanite-epidote coronae around monazite formed at about 60 Ma. They postdate a main mylonitic foliation and predate a second shear band foliation. Deformation of quartz is controlled by crystallographic orientation: Dislocation glide in favourable orientation forms elongate high-aspect-ratio grains. Localised recrystallisation takes place at sites of increased dislocation densities in less favourable oriented quartz and distributed microcracking in unfavourable orientation. Distributed microcracking of quartz occurred quasi-instantaneously coeval with cataclastic deformation of garnet and tourmaline, indicating transient high stresses. During subsequently decreasing stresses, small isometric quartz grains precipitate within the shear band boundaries from the pore fluid, probably derived from recrystallisation of fluid-rich quartz porphyroclasts. Cataclasites with mylonitic components record a coeval or subsequent stage of transient deformation, reflecting the main activity of the DAV with uplift from greenschist facies conditions. The mylonitic pegmatites record systematically changing deformation mechanisms during episodic deformation at greenschist facies conditions dominantly governed by changing stresses and strain-rates, as opposed to changing temperatures.
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Heredia, C., Guedron, S., Point, D., Perrot, V., Campillo, S., Verin, C., et al. (2022). Anthropogenic eutrophication of Lake Titicaca (Bolivia) revealed by carbon and nitrogen stable isotopes fingerprinting. Science Of The Total Environment, 845.
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Herrera, C., Pasten-Araya, F., Cabrera, L., Potin, B., Rivera, E., Ruiz, S., et al. (2022). Rupture properties of the 2020 M-w 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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Hoyos, M. C., & Hernandez, A. F. (2022). Seismic Risk Assessment of Multiple Cities: Biases in the Vulnerability Derivation Methods for Urban Areas With Different Hazard Levels. Frontiers In Earth Science, 10.
Résumé: Previously, it has been shown that probabilistic seismic risk assessments (PSRAs) at urban scale present important discrepancies when compared with analyses conducted using methodologies from regional or national PSRA. However, conducting site-specific urban-scale analyses for a considerable number of cities may not be feasible due to limitations in time, resources, and in some cases availability of information, and thus more general models or methodologies are used. This brings into the picture the importance of identifying and quantifying the possible biases, discrepancies, and uncertainties when using different methods, both in the hazard and vulnerability components. Regarding the latter, several sources of uncertainty and biases have been identified in 1) the selection of ground motion records, either by using a general pool of records such as the ones from FEMA P695 or by performing a site- or hazard-specific analysis that requires a significant effort, especially in areas with a poor history of seismic instrumentation and even more in regions with no evidence of previous PSRA at all; and 2) the fragility or vulnerability derivation nonlinear dynamic methods: incremental dynamic analysis [IDA], cloud analysis [CA], and multi-stripe Analysis [MSA], among others. Focusing on these sources of uncertainty and bias, and with the challenge to bring solutions for places with scarce information, in this study, we aim to explore the use of different vulnerability derivation assumptions for the three principal cities of Colombia: Bogota, Medellin, and Cali, where most of the economic growth is concentrated. This considers the different seismic hazard levels and tectonic environment contributions in each city. Afterward, a comparison between the results of the analysis without the hazard-specific record selection and the site-specific one for each city is performed to establish the cases in which the former is applicable without adding more biases or uncertainties in the process.
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Husson, L., Riel, N., Aribowo, S., Authemayou, C., de Gelder, G., Kaus, B. J. P., et al. (2022). Slow Geodynamics and Fast Morphotectonics in the Far East Tethys. Geochemistry Geophysics Geosystems, 23(1).
Résumé: How can the sluggish, long-wavelength mantle convection be expressed by so many time and space scales of morphotectonic activity? To investigate these relationships, we explore the Java-Banda subduction zone, where geodynamic records cluster. In the far-East Tethys, the exceptionally arcuate Banda subduction zone circumscribes the deepest oceanic basin on Earth, seismotectonic activity slices the upper plate more efficiently than anywhere else, and uncommonly vast expanses of continents are flooded in Sundaland and Northern Australia. By comparing numerical simulations of subduction dynamics to a set of independent observations, we reveal the many facets of tectonic and physiographic changes that the sole docking of the Australian continent onto the subduction zone triggered. While mantle flow remains slow and long-wavelength at depth, intense tectonic activity, and dynamic uplift and subsidence profoundly rework the physiography at many spatial scales. These results demonstrate that a modest disruption in the slow geodynamic tempo may trigger manifold morphotectonic disturbances.
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Husson, L., Salles, T., Lebatard, A. - E., Zerathe, S., Braucher, R., Noerwidi, S., et al. (2022). Javanese Homo erectus on the move in SE Asia circa 1.8 Ma. Scientific Reports, 12(1).
Résumé: The migration of Homo erectus in Southeast Asia during Early Pleistocene is cardinal to our comprehension of the evolution of the genus Homo. However, the limited consideration of the rapidly changing physical environment, together with controversial datings of hominin bearing sites, make it challenging to secure the robust timeline needed to unveil the behavior of early humans. Here, we reappraise the first appearance datum ofJavanese H. erectus by adding the most reliable age constraints based on cosmogenic nuclides Be-10 and Al-26 produced in situ to a compilation of earlier estimates. We find that H. erectus reached Java and dwelled at Sangiran, Java, ca. 1.8 Ma. Using this age as a baseline, we develop a probabilistic approach to reconstruct their dispersal routes, coupling ecological movement simulations to landscape evolution models forced by reconstructed geodynamic and climatic histories. We demonstrate that the hospitable terra firma conditions of Sundaland facilitated the prior dispersal of hominins to the edge of Java, where they conversely could not settle until the Javanese archipelago emerged from the sea and connected to Sundaland. The dispersal of H. erectus across Sundaland occurred over at least tens to hundreds kyr, a time scale over which changes in their physical environment, whether climatic or physiographic, may have become primary forcings on their behavior. Our comprehensive reconstruction method to unravel the peopling timeline of SE Asia provides a novel framework to evaluate the evolution of early humans.
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Irnaka, T. M., Brossier, R., Metivier, L., Bohlen, T., & Pan, Y. (2022). 3-D multicomponent full waveform inversion for shallow-seismic target: Ettlingen Line case study. Geophysical Journal International, 229(2), 1017–1040.
Résumé: In this work, we investigate methodological development and application of viscoelastic full waveform inversion to a multicomponent source and receiver data set at the near-surface scale. The target is located in Germany and lies in an ancient war trench from the War of the Spanish Succession that was buried at approximately 1 m depth. We present the pre-processing of the data, including a matching filter correction to compensate for different source and receiver coupling conditions during the acquisition, as well as a dedicated multistep workflow for the reconstruction of both P-wave and S-wave velocities. Our implementation is based on viscoelastic modelling using a spectral element discretization to accurately account for the wave propagation complexity in this shallow region. We illustrate the inversion stability by starting from different initial models, either based on dispersion curve analysis or homogeneous models consistent with first arrivals. We recover similar results in both cases. We also illustrate the importance of accounting for the attenuation by comparing elastic and viscoelastic results. The 3-D results make it possible to recover and locate the trench precisely in terms of interpretation. They also exhibit another trench structure, in a direction forming an angle at 45 degrees with the direction of the targeted trench. This new structure had been previously interpreted as an artifact in former 2-D inversion results. The archaeological interpretation of this new structure is still a matter of discussion.
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Isa, J., Orthous-Daunay, F. - R., Vuitton, V., Flandinet, L., Zandanel, A., Truche, L., et al. (2022). Secondary SOM produced through aqueous alteration on carbonaceous chondrite parent bodies: anomalies from mass distributions. Meteoritics & Planetary Science, 57.
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Itoh, Y., Aoki, Y., & Fukuda, J. (2022). Imaging evolution of Cascadia slow-slip event using high-rate GPS. Scientific Reports, 12(1).
Résumé: The slip history of short-term slow slip event (SSE) is typically inferred from daily Global Positioning System (GPS) data, which, however, cannot image the sub-daily processes, leaving the underlying mechanisms of SSEs elusive. To address the temporal resolution issue, we attempted to employ the kinematic subdaily GPS analysis, which has never been applied to SSE studies because its signal-to-noise ratio has been believed too low. By carefully post-processing sub-daily positions to remove non-tectonic position fluctuation, our 30-min kinematic data clearly exhibits the transient motion of a few mm during one Cascadia SSE. A spatiotemporal slip image by inverting the 30-min data exhibits a multi-stage evolution; it consists of an isotropic growth of SSE followed by an along-strike migration and termination within the rheologically controlled down-dip width. This transition at the slip growth mode is similar to the rupture growth of regular earthquakes, implying the presence of common mechanical factors behind the two distinct slip phenomena. The comparison with a slip inversion of the daily GPS demonstrates the current performance and limitation of the subdaily data in the SSE detection and imaging. Better understanding of the non-tectonic noise in the kinematic GPS analysis will further improve the temporal resolution of SSE.
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Jaillard, E. (2022). Late Cretaceous-Paleogene orogenic build-up of the Ecuadorian Andes: Review and discussion. Earth-Science Reviews, 230.
Résumé: A review of the tectonic events recorded by sediments on the Andean continental margin of northern Peru and Ecuador and on the accreted oceanic terranes of Ecuador, allows to identify three tectonic events of late Campanian to late Paleocene age (-75 to-55 Ma). Each tectonic event resulted in the arrival of quartz-rich deposits on the oceanic units and in a sedimentary hiatus in the backarc zone (Oriente basin), which both indicate an uplift of the South-American continental margin. This is interpreted as the underplating of oceanic terranes beneath the Andean continental margin. After the Incaic contractional phase (-40 Ma), the Oriente Basin recorded a sharp increase in the subsidence rate, the westward migration of the depocenters and a drastic change in the detrital source around 25 Ma, which indicate the onset of its foreland basin evolution, driven by flexural subsidence. It is therefore proposed that the Ecuadorian Andes resulted first from the evolution of a western, west-verging orogenic wedge, made of accreted oceanic material (-75-40 Ma). Once this western wedge overthickened and submitted to strong vertical body forces, the strain related to ocean-continent convergence was transmitted to the continental plate, where a second, eastern, east-verging orogenic wedge formed about 25 Ma ago. This scenario accounts for the tectonic and sedimentary evolution of the Ecuadorian-north Peruvian margin, and explains why, in spite of a moderate elevation, the partly oceanic crustal root of the Ecuadorian Andes, is almost as thick as beneath the high-altitude Altiplano of southern Peru and Bolivia, where the crustal root is mainly of continental nature.
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Jara-Munoz, J., Melnick, D., Li, S., Socquet, A., Cortes-Aranda, J., Brill, D., et al. (2022). The cryptic seismic potential of the Pichilemu blind fault in Chile revealed by off-fault geomorphology. Nature Communications, 13(1).
Résumé: The first step towards assessing hazards in seismically active regions involves mapping capable faults and estimating their recurrence times. While the mapping of active faults is commonly based on distinct geologic and geomorphic features evident at the surface, mapping blind seismogenic faults is complicated by the absence of on-fault diagnostic features. Here we investigated the Pichilemu Fault in coastal Chile, unknown until it generated a Mw 7.0 earthquake in 2010. The lack of evident surface faulting suggests activity along a partly-hidden blind fault. We used off-fault deformed marine terraces to estimate a fault-slip rate of 0.52 +/- 0.04 m/ka, which, when integrated with satellite geodesy suggests a 2.12 +/- 0.2 ka recurrence time for Mw similar to 7.0 normal-faulting earthquakes. We propose that extension in the Pichilemu region is associated with stress changes during megathrust earthquakes and accommodated by sporadic slip during upper-plate earthquakes, which has implications for assessing the seismic potential of cryptic faults along convergent margins and elsewhere.
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Jiang, L., Zhang, Z., & Roux, P. (2022). Three-dimensional higher-order raypath separation in a shallow-water waveguide. Jasa Express Letters, 2(7).
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Jiao Liqing, Chan Chung-Han, Scholtes, L., Hubert-Ferrai, A., Donze, F. - V., & Tapponnier, P. (2022). Discrete Element Modeling of a Subduction Zone with a Seafloor Irregularity and its Impact on the Seismic Cycle. Acta Geologica Sinica-English Edition, 96(3), 776–790.
Résumé: Seafloor irregularities influence rupture behavior along the subducting slab and in the overriding plate, thus affecting earthquake cycles. Whether seafloor irregularities increase the likelihood of large earthquakes in a subduction zone remains contested, partially due to focus put either on fault development or on rupture pattern. Here, we simulate a subducting slab with a seafloor irregularity and the resulting deformation pattern of the overriding plate using the discrete element method. Our simulations illustrate the rupture along three major fault systems: megathrust, splay and backthrust faults. Our results show different rupture dimensions of earthquake events varying from tens to ca. 140 km. Our results suggest that the recurrence interval of megathrust events with rupture length of ca. 100 km is ca. 140 years, which is overall comparable to the paleoseismic records at the Mentawai area of the Sumatran zone. We further propose the coseismic slip amounts decrease and interseismic slip amounts increase from the surface downwards gradually. We conclude that the presence of seafloor irregularities significantly affects rupture events along the slab as well as fault patterns in the overriding plate.
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Jiskra, M., Guedron, S., Tolu, J., Fritz, S. C., Baker, P. A., & Sonke, J. E. (2022). Climatic Controls on a Holocene Mercury Stable Isotope Sediment Record of Lake Titicaca. Acs Earth And Space Chemistry, 6(2), 346–357.
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Johnson, J. R., Hansen, J. A., Rahman, M. J., Renard, F., & Mondol, N. H. (2022). Mapping the maturity of organic-rich shale with combined geochemical and geophysical data, Draupne Formation, Norwegian Continental Shelf. Marine And Petroleum Geology, 138.
Résumé: The evaluation of the interplay between kerogen maturation and total organic carbon (TOC) content within an organic-rich shale is critical to characterizing source rock shale's elastic behavior. We analysed a comprehensive database of twenty-nine well logs, two 3D seismic surveys, and geochemical data of eighteen wells within the Draupne Formation in the Norwegian North Sea. The Upper Jurassic (Kimmeridgian) Draupne Formation Shale is found throughout the Norwegian Continental Shelf and is the primary source, carrier, and seal rock in several oil and gas fields. The dataset explores a broad range of depths (2-5 km), total organic contents (0-20 wt%), and various maturation states ranging from immature to overmature. We study the relationship between rock brittleness and organic content as shale matures. We use calculated values of Young's modulus and Poisson's ratio. Academic and industry-standard cutoffs are applied to both the TOC content and maturation level. We introduce here the Organic Maturation Product (OMP) rock physics template, which incorporates a relationship between organic content and any subsequent maturation. The degree of brittleness or ductility is impacted directly by the kerogen maturation process, with lower TOC content having a dampening effect on the transition towards increasing brittleness. This template allows one to classify rock maturation in nine categories, from low to high maturation, and link these categories to rock geomechanical properties. Seismic inversion of the 3D surveys and mapping utilizing the OMP classification reveal how large-scale depositional environment and subsequent diagenetic events influence both placement and quality of source rock broadly within the basin context of the North Sea.
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Johnson, J. R., Kobchenko, M., Johnson, A. C., Mondol, N. H., & Renard, F. (2022). Experimental modelling of primary migration in a layered, brittle analogue system. Tectonophysics, 840.
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Johnson, J. R., Kobchenko, M., Mondol, N. H., & Renard, F. (2022). Multiscale synchrotron microtomography imaging of kerogen lenses in organic-rich shales from the Norwegian Continental Shelf. International Journal Of Coal Geology, 253.
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Journeau, C., Shapiro, N. M., Seydoux, L., Soubestre, J., Koulakov, I. Y., Jakovlev, A., V, et al. (2022). Seismic tremor reveals active trans-crustal magmatic system beneath Kamchatka volcanoes. Science Advances, 8(5).
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Karabulut, H., Bouchon, M., & Schmittbuhl, J. (2022). Synchronization of small-scale seismic clusters reveals large-scale plate deformation. Earth Planets And Space, 74(1).
Résumé: It has long been observed that periods of intense seismic activity in a region alternate with periods of relative quiescence, but establishing whether or not this intermittency is driven by broad-scale physical processes occurring in the Earth, remains a challenge. Here, we address this question of long-range triggering by a large-scale analysis of evolution of the seismicity between 2003 and 2017 in the Anatolia region. Two multi-year periods of synchronous high seismicity rate in 27 seismicity clusters across the Anatolian plate are evidenced before a relatively uniform quiescence period. We argue that two remote tectonic processes are important for the timing of these activities: the 2004 M9.2 Sumatra earthquake and the 2008-2011 episode of slab rollback/deformation in the Hellenic subduction, even if a clear causal mechanism is still lacking.
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Karas, A., Karbou, F., Giffard-Roisin, S., Durand, P., & Eckert, N. (2022). Automatic Color Detection-Based Method Applied to Sentinel-1 SAR Images for Snow Avalanche Debris Monitoring. Ieee Transactions On Geoscience And Remote Sensing, 60.
Résumé: In this study, we develop a novel method to automatically detect areas of snow avalanche debris using a color space segmentation technique applied to synthetic aperture radar (SAR) image time series through January 2018 in the Swiss Alps. Debris avalanche zones are detected assuming that these areas are characterized by a significant and localized increase in SAR signal relative to the surrounding environment. We undertake a sensitivity study by calculating debris products by varying the D-M reference images (a stable reference image taken several weeks before the event). We examine the results according to the direction of the orbit, the characteristics of the terrain (slope, altitude, orientation), and also by evaluating the relevance of the detection with the help of an independent SPOT database by Hafner and Buhler [1] including 18 737 avalanche events. Small avalanches are not detected by SAR images, and depending on the orientation of the terrain some avalanches are not detected by either the ascending or the descending orbit. The detection results vary with the reference image; best detection results are obtained with some selected individual dates with almost 70% of verified avalanche events using the ascending orbit.
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Kartseva, T., I, Shapiro, N. M., Patonin, A., V, Smirnov, V. B., & Ponomarev, A., V. (2022). Energy Classification of Acoustic Events Using the Coda of a Signal. Seismic Instruments, 58(1), 18–25.
Résumé: A new energy classification method is proposed for acoustic events recorded in laboratory experiments on rock destruction. The method analyzes the coda waves of acoustic emission (AE) events. Coda waves are considered as reverberation of the acoustic field in the test sample. The new classification was tested on two experiments carried out on different rocks: granites of the Voronezh massif and Berea sandstone, on an INOVA-1000 controlled hydraulic press at the Borok Geophysical Observatory (GO), Schmidt Institute of Physics of the Earth, Russian Academy of Sciences (IPE RAS). Comparison of the new classification with the one used at Borok GO showed that both methods give well consistent results in the middle range of energies of AE events. For strong events with the saturated initial parts of the signals due to the limitations of the recording equipment, the new technique demonstrated better results, leading to energy estimates of such events from the undistorted coda of the signal.
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Kawaguchi, S., I, Morard, G., Kuwayama, Y., Hirose, K., Hirao, N., & Ohishi, Y. (2022). Density determination of liquid iron-nickel-sulfur at high pressure. American Mineralogist, 107(7), 1254–1261.
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Kian, Y., Soccorsi, E., Xue, Q., & Yamamoto, M. (2022). Identification Of Time-Varying Source Term In Time-Fractional Evolution Equations. Communications In Mathematical Sciences, 20(1), 53–84.
Résumé: This paper is concerned with the inverse problem of determining the time-and space-dependent source term of diffusion equations with constant-order time-fractional derivative in (0, 2). We examine two different cases. In the first one, the source is the product of a spatial term and a temporal term, and we prove that the term depending on the space variable can be retrieved by observation over the time interval of the solution on an arbitrary sub-boundary. Under some suitable assumptions we can also show the simultaneous recovery of the spatial term and the temporal term. In the second case, we assume that the first term of the product varies with one fixed space variable, while the second one is a function of all the remaining space and time variables, and we show that they are uniquely determined by one arbitrary lateral measurement of the solution. These source identification results boil down to a weak unique continuation principle in the first case and a unique continuation principle for Cauchy data in the second one, that are preliminarily established. Finally, numerical reconstruction of the spatial term in the first case is carried out through an iterative algorithm based on the Tikhonov regularization method.
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King, A., Guignot, N., Henry, L., Morard, G., Clark, A., Le Godec, Y., et al. (2022). Combined angular and energy dispersive diffraction: optimized data acquisition, normalization and reduction. Journal Of Applied Crystallography, 55, 218–227.
Résumé: Combined angular and energy dispersive diffraction is particularly well suited to experiments at high pressures in large-volume presses, and to the study of liquid or amorphous systems. This work describes the data acquisition, correction and reduction approach developed at the PSICHE beamline of the SOLEIL synchrotron. The measured data were normalized for both the scattering volume and the effective incident energy spectrum. By optimizing the acquisition strategy, the measurement time and radiation dose are greatly reduced. The correction and reduction protocol outputs normalized scattering profiles that are suitable for pair distribution function or liquid structure analysis. These processes are demostrated with examples from a number of real experimental data sets.
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Kjar, K. H., Winther Pedersen, M., De Sanctis, B., De Cahsan, B., Korneliussen, T. S., Michelsen, C. S., et al. (2022). A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA. Nature, 612(7939), 283–291.
Résumé: Late Pliocene and Early Pleistocene epochs 3.6 to 0.8 million years ago1 had climates resembling those forecasted under future warming2. Palaeoclimatic records show strong polar amplification with mean annual temperatures of 11-19°C above contemporary values3,4. The biological communities inhabiting the Arctic during this time remain poorly known because fossils are rare5. Here we report an ancient environmental DNA6 (eDNA) record describing the rich plant and animal assemblages of the Kap Kobenhavn Formation in North Greenland, dated to around two million years ago. The record shows an open boreal forest ecosystem with mixed vegetation of poplar, birch and thuja trees, as well as a variety of Arctic and boreal shrubs and herbs, many of which had not previously been detected at the site from macrofossil and pollen records. The DNA record confirms the presence of hare and mitochondrial DNA from animals including mastodons, reindeer, rodents and geese, all ancestral to their present-day and late Pleistocene relatives. The presence of marine species including horseshoe crab and green algae support a warmer climate than today. The reconstructed ecosystem has no modern analogue. The survival of such ancient eDNA probably relates to its binding to mineral surfaces. Our findings open new areas of genetic research, demonstrating that it is possible to track the ecology and evolution of biological communities from two million years ago using ancient eDNA.
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Koishi, A., Lee, S. S., Fenter, P., Fernandez-Martinez, A., & Bourg, I. C. (2022). Water Adsorption on Mica Surfaces with Hydrophilicity Tuned by Counterion and and Structural Fluorination. Journal Of Physical Chemistry C, .
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Koishi, A., Lee, S. S., Fenter, P., Fernandez-Martinez, A., & Bourg, I. C. (2022). Water Adsorption on Mica Surfaces with Hydrophilicity Tuned by Counterion Types (Na, K, and Cs) and Structural Fluorination. Journal Of Physical Chemistry C, 126(38), 16447–16460.
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Koshlyakova, A. N., Sobolev, A. V., Krasheninnikov, S. P., Batanova, V. G., & Borisov, A. A. (2022). Ni partitioning between olivine and highly alkaline melts: An experimental study. Chemical Geology, 587.
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Kotha, S. R., Bindi, D., & Cotton, F. (2022). A regionally adaptable ground-motion model for fourier amplitude spectra of shallow crustal earthquakes in Europe. Bulletin Of Earthquake Engineering, 20(2), 711–740.
Résumé: Typical seismic ground-motion models predict the response spectral ordinates (GMM-SA), which are the damped responses of a suite of single-degree-of-freedom oscillators. Response spectra represent the response of an idealized structure to input ground-motion, but not the physics of the actual ground-motion. To complement the regionally adaptable GMM-SA of Kotha et al. (2020), we introduce a model capable of predicting Fourier amplitudes (GMM-FA); developed from the Engineering Strong Motion (ESM) dataset for pan-Europe. This GMM-FA reveals the very high variability of high frequency ground-motions, which are completely masked in a GMM-SA. By maintaining the development strategies of GMM-FA identical to that of the GMM-SA, we are able to evaluate the physical meaning of the spatial variability of anelastic attenuation and source characteristics. We find that a fully data-driven geospatial index, Activity Index (AIx), correlates well with the spatial variability of these physical effects. AIx is a fuzzy combination of seismicity and crustal parameters, and can be used to adapt the attenuation and source non-ergodicity of the GMM-FA to regions and tectonic localities sparsely sampled in ESM. While AIx, and a few other parameters we touch upon, may help understand the spatial variability of high frequency attenuation and source effects, the high frequency site-response variability-dominating the overall aleatory variance-is yet unresolvable. With the rapid increase in quantity and quality of ground-motion datasets, our work demonstrates the need to upgrade regionalization techniques, site-characterisation, and a paradigm shift towards Fourier ground-motion models to complement the traditional response spectra prediction models.
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Kotha, S. R., Weatherill, G., Bindi, D., & Cotton, F. (2022). Near-source magnitude scaling of spectral accelerations: analysis and update of Kotha et al. (2020) model. Bulletin Of Earthquake Engineering, 20(3), 1343–1370.
Résumé: Ground-motion models (GMMs) are often used to predict the random distribution of Spectral accelerations (SAs) at a site due to a nearby earthquake. In probabilistic seismic hazard and risk assessment, large earthquakes occurring close to a site are considered as critical scenarios. GMMs are expected to predict realistic SAs with low within-model uncertainty (sigma(mu)) for such rare scenarios. However, the datasets used to regress GMMs are usually deficient of data from critical scenarios. The (Kotha et al., A Regionally Adaptable Ground-Motion Model for Shallow Crustal Earthquakes in Europe Bulletin of Earthquake Engineering 18:4091-4125, 2020) GMM developed from the Engineering strong motion (ESM) dataset was found to predict decreasing short-period SAs with increasing M-W >= M-h = 6.2, and with large sigma(mu) at near-source distances <= 30km. In this study, we updated the parametrisation of the GMM based on analyses of ESM and the Near source strong motion (NESS) datasets. With M-h = 5.7, we could rectify the M-W scaling issue, while also reducing sigma(mu). at M-W >= M-h. We then evaluated the GMM against NESS data, and found that the SAs from a few large, thrust-faulting events in California, New Zealand, Japan, and Mexico are significantly higher than GMM median predictions. However, recordings from these events were mostly made on soft-soil geology, and contain anisotropic pulse-like effects. A more thorough non-ergodic treatment of NESS was not possible because most sites sampled unique events in very diverse tectonic environments. We provide an updated set of GMM coefficients,sigma(mu), and heteroscedastic variance models; while also cautioning against its application for M-W <= 4 in low-moderate seismicity regions without evaluating the homogeneity of M-W estimates between pan-European ESM and regional datasets.
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Lacroix, P., Belart, J. M. C., Berthier, E., Saemundsson, T., & Jonsdottir, K. (2022). Mechanisms of Landslide Destabilization Induced by Glacier-Retreat on Tungnakvislarjokull Area, Iceland. Geophysical Research Letters, 49(14).
Résumé: The massive worldwide deglaciation leads to more frequent slope instabilities in mountainous terrains. The physical processes leading to such destabilizations are poorly constrained due to little monitoring of dynamic parameters at the local scale. Here we study a very large slow-moving landslide (similar to 0.8 km(2)), on the flank of Tungnakvislarjokull glacier in Iceland. Based on a combination of remote sensing images, we monitor the landslide and glacier kinematics over 75 years, with a focus over the period 1999-2019 when rapid glacier wastage has been observed. The landslide accelerates from 2 to 45 m/yr in the 6 years following a sudden increase in glacier mass loss. This acceleration coincides with intense quake activity (Ml < 2.8), recorded by a regional seismic network. We show that this seismicity is caused by the landslide sliding on a rough surface. The evolution of the quake magnitudes suggests a progressive segmentation of the landslide mass during its acceleration.
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Lacroix, P., Gavillon, T., Bouchant, C., Lave, J., Mugnier, J. - L., Dhungel, S., et al. (2022). SAR and optical images correlation illuminates post-seismic landslide motion after the Mw 7.8 Gorkha earthquake (Nepal). Scientific Reports, 12(1).
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Landeau, M., Fournier, A., Nataf, H. - C., Cebron, D., & Schaeffer, N. (2022). Sustaining Earth's magnetic dynamo. Nature Reviews Earth & Environment, 3(4), 255–269.
Résumé: Earth's magnetic field is generated by fluid motions in the outer core. This geodynamo has operated for over 3.4 billion years. However, the mechanism that has sustained the geodynamo for over 75% of Earth's history remains debated. In this Review, we assess the mechanisms proposed to drive the geodynamo (precession, tides and convection) and their ability to match geomagnetic and palaeomagnetic observations. Flows driven by precession are too weak to drive the geodynamo. Flows driven by tides could have been strong enough in the early Earth, before 1.5 billion years ago, when tidal deformation and Earth's spin rate were larger than they are today. Evidence that the thermal conductivity of Earth's core could be as high as 250 W m(-1) K-1 calls the ability of convection to maintain the dynamo for over 3.4 billion years into question. Yet, convection could supply enough power to sustain a long-lived geodynamo if the thermal conductivity is lower than 100 W m(-1) K-1. Exsolution of light elements from the core increases this upper conductivity limit by 15% to 200%, based on the exsolution rates reported so far. Convection, possibly aided by the exsolution of light elements, remains the mechanism most likely to have sustained the geodynamo. The light-element exsolution rate, which remains poorly constrained, should be further investigated. The mechanisms that sustain Earth's long-lived geodynamo remain under scrutiny. This Review assesses the potential candidates-convection, precession and tides-revealing that convection, possibly helped by the exsolution of light elements, is the most likely scenario.
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Lanson, B., Mignon, P., Velde, M., Bauer, A., Lanson, M., Findling, N., et al. (2022). Determination of layer charge density in expandable phyllosilicates with alkylammonium ions: A combined experimental and theoretical assessment of the method. Applied Clay Science, 229.
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Large, E., Huyghe, P., Mugnier, J. - L., Guillier, B., Taral, S., Gyawali, B. R., et al. (2022). Distribution of active tectonics in the Himalayan piedmont (Darjeeling, eastern India) inferred from Horizontal-to-Vertical spectral ratio analysis of passive seismic records. Terra Nova, 34(6), 535–542.
Résumé: The pattern of active deformation of frontal structures in Darjeeling Himalaya is complex with out-of-sequence reactivations in the chain and development of scarps associated with earthquake ruptures reaching the surface in the piedmont. To clarify the distribution of active deformation in this area, we analyse passive seismic records by the Horizontal-to-Vertical Spectral Ratio method along three NS trending profiles. We image the Siwalik sedimentary rocks / recent deposits interface under the piedmont and show folded and faulted geometries. Two of these faults are located under scarps of about 10 m affecting the 3.7 +/- 0.7 ka old surface of the Tista megafan. Such features imply that about half of the convergence is expressed south of the Himalayan front while the other part occurs out-of-sequence in the chain, suggesting a very limited activity of the Main Frontal Thrust itself.
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Lauer, A. R., Duran-Olivencia, M. A., Fernandez-Martinez, A., & Van Driessche, A. E. S. (2022). Multistep nucleation compatible with a single energy barrier: catching the non-classical culprit. Faraday Discussions, 235, 95–108.
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Le Bars, M., Barik, A., Burmann, F., Lathrop, D. P., Noir, J., Schaeffer, N., et al. (2022). Fluid Dynamics Experiments for Planetary Interiors. Surveys In Geophysics, 43(1), 229–261.
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Le Bars, M., Levard, C., Legros, S., Vidal, V., Fernandez-Martinez, A., Michel, F. M., et al. (2022). Size and Strain of Zinc Sulfide Nanoparticles Altered by Interaction with Organic Molecules. Environmental Science & Technology, .
Résumé: Nanosized zinc sulfides (nano-ZnS) have size-dependent and tunable physical and chemical properties that make them useful for a variety of technological applications. For example, structural changes, especially caused by strain, are pronounced in nano-ZnS < 5 nm in size, the size range typical of incidental nano-ZnS that form in the environment. Previous research has shown how natural organic matter impacts the physical properties of nano-ZnS but was mostly focused on their aggregation state. However, the specific organic molecules and the type of functional groups that are most important for controlling the nano-ZnS size and strain remain unclear. This study examined the size-dependent strain of nano-ZnS synthesized in the presence of serine, cysteine, glutathione, histidine, and acetate. Synchrotron total scattering pair distribution function analysis was used to determine the average crystallite size and strain. Among the different organic molecules tested, those containing a thiol group were shown to affect the particle size and size-induced strain most strongly when added during synthesis but significantly reduced the particle strain when added to as-formed nano-ZnS. The same effects are useful to understand the properties and behavior of natural nano-ZnS formed as products of microbial activity, for example, in reducing environments, or of incidental nano-ZnS formed in organic wastes.
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Le Boulzec, H., Delannoy, L., Andrieu, B., Verzier, F., Vidal, O., & Mathy, S. (2022). Dynamic modeling of global fossil fuel infrastructure and materials needs: a lack of available data. Applied Energy, 326.
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Le Breton, M., Liebault, F., Baillet, L., Charlety, A., Larose, E., & Tedjini, S. (2022). Dense and long-term monitoring of earth surface processes with passive RFID-a review. Earth-Science Reviews, 234.
Résumé: Billions of Radio-Frequency Identification (RFID) passive tags are produced yearly to identify goods remotely. New research and business applications are continuously arising, including recently localization and sensing to monitor earth surface processes. Indeed, passive tags can cost 10 to 100 times less than wireless sensors networks and require little maintenance, facilitating years-long monitoring with ten's to thousands of tags. This study reviews the existing and potential applications of RFID in geosciences. The most mature application today is the study of coarse sediment transport in rivers or coastal environments, using tags placed into pebbles. More recently, tag localization was used to monitor landslide displacement, with a centimetric accuracy. Sensing tags were used to detect a displacement threshold on unstable rocks, to monitor the soil moisture or temperature, and to monitor the snowpack temperature and snow water equivalent. RFID sensors, available today, could monitor other parameters, such as the vibration of structures, the tilt of unstable boulders, the strain of a material, or the salinity of water. Key challenges for using RFID monitoring more broadly in geosciences include the use of ground and aerial vehicles to collect data or localize tags, the increase in reading range and duration, the ability to use tags placed under ground, snow, water or vegetation, and the optimization of economical and environ-mental cost. As a pattern, passive RFID could fill a gap between wireless sensor networks and manual mea-surements, to collect data efficiently over large areas, during several years, at high spatial density and moderate cost.
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Lefeuvre, N., Truche, L., Donze, F. -, V, Gal, F., Tremosa, J., Fakoury, R. - A., et al. (2022). Natural hydrogen migration along thrust faults in foothill basins: The North Pyrenean Frontal Thrust case study. Applied Geochemistry, 145.
Résumé: The existence of geological fluids rich in natural hydrogen (H2) raises the question about the energy potential of this carbon-free resource. However, to date there is no exploration strategy based on robust methodologies and pathfinders. Therefore, it is important to develop an exploration guide that is not only focused on surface gas monitoring, but that also considers the local deep geological setting integrating the entire hydrogen system from source to trap or leakage into the atmosphere. The northwestern Pyrenees, and particularly the Maule acute accent on Basin, represent a promising geological environment for natural H2 exploration for at least four reasons. First, an ultramafic mantle body is emplaced at shallow depth below the basin under pressure-temperature conditions favorable to serpentinization. Second, major faults such as the North Pyrenean Frontal Thrust constitute large-scale fluid flow convergence and drainage. Third, hydraulic gradients imposed by sharp reliefs and combined with temperature and pressure gradients trigger fluid migration. Fourth, impermeable sedimentary formations or caprocks such as evaporites or claystones overly porous reservoir rocks that could constitute traps for accumulating H2. To investigate H2 migration at the fault scale, we present new geochemical and geophysical data recorded along the North Pyrenean Frontal Thrust. Based on both soil gas and electromagnetic transects, we reveal the presence of a gas-draining fault. Soil gas concentration (H2, CO2, CH4 and 222Rn) recorded at 1 m depth increases when approaching the North Pyrenean Frontal Thrust. The maximum H2, CO2 and 222Rn concentrations recorded in the fault zone are 822 ppmv, 10.3 vol% and 57 kBq.m? 3, respectively -whereas their local background concentrations are by 1-2 orders of magnitude lower: 10 ppmv, 0.2 vol% and 0.3 kBq.m? 3 respectively. Our geochemical and geophysical data support the concept of a deep-fluid migration along the detected fault plane. In addition, the study of historical well data combined with the most recent geological and geophysical surveys carried out in the region, highlights zones where H2 could accumulate at depth. The Triassic salt formations, located at 2800 to 4000 m deep beneath the Maule acute accent on Basin, represent the most promising trap for H2 in the northwestern Pyrenees.
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Lehmann, B., Anderson, R. S., Bodin, X., Cusicanqui, D., Valla, P. G., & Carcaillet, J. (2022). Alpine rock glacier activity over Holocene to modern timescales (western French Alps). Earth Surface Dynamics, 10(3), 605–633.
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Lesur, V., Gillet, N., Hammer, M. D., & Mandea, M. (2022). Rapid Variations of Earth's Core Magnetic Field. Surveys In Geophysics, 43(1), 41–69.
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Lherm, V., Deguen, R., Alboussiere, T., & Landeau, M. (2022). Rayleigh-Taylor instability in impact cratering experiments. Journal Of Fluid Mechanics, 937.
Résumé: When a liquid drop strikes a deep pool of a target liquid, an impact crater opens while the liquid of the drop decelerates and spreads on the surface of the crater. When the density of the drop is larger than the target liquid, we observe mushroom-shaped instabilities growing at the interface between the two liquids. We interpret this instability as a spherical Rayleigh-Taylor instability due to the deceleration of the interface, which exceeds the ambient gravity. We investigate experimentally the effect of the density contrast and the impact Froude number, which measures the importance of the impactor kinetic energy to gravitational energy, on the instability and the resulting mixing layer. Using backlighting and planar laser-induced fluorescence methods, we obtain the position of the air-liquid interface, an estimate of the instability wavelength, and the thickness of the mixing layer. We derive a model for the evolution of the crater radius from an energy conservation. We then show that the observed dynamics of the mixing layer results from a competition between the geometrical expansion of the crater, which tends to thin the layer, and entrainment related to the instability, which increases the layer thickness. The mixing caused by this instability has geophysical implications for the impacts that formed terrestrial planets. Extrapolating our scalings to planets, we estimate the mass of silicates that equilibrates with the metallic core of the impacting bodies.
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Liu, D., Zhao, L., Paul, A., Yuan, H., Solarino, S., Aubert, C., et al. (2022). Receiver function mapping of the mantle transition zone beneath the Western Alps: New constraints on slab subduction and mantle upwelling. Earth And Planetary Science Letters, 577.
Résumé: To better constrain the deep structure and dynamics of the Western Alps, we studied the mantle transition zone (MTZ) structure using P-wave receiver functions (RFs). We obtained a total of 24904 RFs from 1182 events collected by 307 stations in the Western Alps. To illustrate the influence of the heterogeneity on the upper mantle velocity, we used both IASP91 and three-dimensional (3-D) velocity models to perform RF time-to-depth migration. We documented an MTZ thickening of about 40 km under the Western Alps and most of the Po Plain due to the uplift associated with the 410-km discontinuity and the depression associated with the 660-km discontinuity. Based upon the close spatial connection between the thickened MTZ and the location of the subducted slabs, we proposed that the thick MTZ was due to the subduction of the Alpine slab through the upper MTZ and the presence of remnants of subducted oceanic lithosphere in the MTZ. The uplift associated with the 410-km discontinuity provided independent evidence of the subduction depth of the Western Alps slab. In the Alpine foreland in eastern France, we observed localized arc-shaped thinning of the MTZ caused by a 12 km depression of the 410-km discontinuity, which has not been previously reported. This depression indicated a temperature increase of 120 K in the upper MTZ, and we proposed that it was caused by a small-scale mantle upwelling. Hardly any uplift of the 660 km discontinuity was observed, suggesting that the thermal anomaly was unlikely to be the result of a mantle plume. We observed that the thinning area of the MTZ corresponded to the area with the highest uplift rate in the Western Alps, which may have indicated that the temperature increase caused by the mantle upwelling contributed to the topographic uplift. (C) 2021 Elsevier B.V. All rights reserved.
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Loncke, L., de Lepinay, M. M., Basile, C., Maillard, A., Roest, W. R., De Clarens, P., et al. (2022). Compared structure and evolution of the conjugate Demerara and Guinea transform marginal plateaus. Tectonophysics, 822.
Résumé: The Demerara and Guinea plateaus are conjugate Transform Marginal Plateaus (TMPs) formed at the junction of the Jurassic Central Atlantic Ocean and the Cretaceous Equatorial Atlantic Ocean. We compare their structure and evolution through a combined industrial/academic seismic dataset tied by well data. We show that these TMPs record a complete evolution history from the Jurassic Central Atlantic to the Equatorial Atlantic breakup and seafloor spreading phases. Both plateaus first formed as volcanic margins displaying successive SDR wedges migrating towards the newly forming Central Atlantic domain. In this context, Demerara and Guinea, conjugates of the Bahamas, seem to have formed in relation to plume activity at the southern end of the Central Atlantic domain. Our dataset suggests that the Demerara and Guinea plateaus initially represented two distinct extrusive centres separated by a crustal basement high. Later, during the Cretaceous Equatorial opening phase, both plateaus separated in a transform mode following this discontinuity. Deformation is notably asymmetric during this phase: Aptian to Albian folding, strike-slip, transtensive deformation and complex vertical movements on the Demerara side and only minor deformation on the Guinean side, except on its divergent Sierra Leone termination. The deformation is sealed on both plateaus by a regional upper Albian erosion unconformity. Extensional reactivation occurs on the Guinea side (probably through a general collapse?). To conclude, this study provides new insights into the nature and origin of TMPs and the key tectono-sedimentary archives they may contain to understand the polyphase breakup conditions of Gondwana.
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Lu, Y., Pedersen, H. A., & Stehly, L. (2022). Mapping the seismic noise field in Europe: spatio-temporal variations in wavefield composition and noise source contributions. Geophysical Journal International, 228(1), 171–192.
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Lupi, M., De Gori, P., Valoroso, L., Baccheschi, P., Minetto, R., & Mazzini, A. (2022). Northward migration of the Javanese volcanic arc along thrust faults. Earth And Planetary Science Letters, 577.
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Madley, M., Yates, A., Savage, M., Wang, W., Okada, T., Matsumoto, S., et al. (2022). Velocity changes around the Kaikoura earthquake ruptures from ambient noise cross-correlations. Geophysical Journal International, 229(2), 1357–1371.
Résumé: Seismic velocity changes before and after large-magnitude earthquakes carry information about damage present in the surrounding region. This study presents temporal velocity changes detected prior to and following the 2016 November M-w 7.8 Kaikoura earthquake in Canterbury, New Zealand. We use continuous waveform data from 11 short-period seismometers within the Kaikoura region with an average interstation distance of 83 km. Nine-component day-long empirical Green's functions were computed for frequencies between 0.1 and 0.9 Hz for continuous seismic records from 2012 January 1 to 2018 February 28, which also include the 2013 Cook Strait and Lake Grassmere earthquakes. Using the moving-window cross-spectral method, seismic velocity changes were calculated. Immediately following the 2016 Kaikoura earthquake, a decrease in seismic velocity averaged across all component pairs of approximately 0.2 per cent was observed. An increase in seismic velocity of approximately 0.1 per cent after the earthquake was visible over a 1.5 yr period averaged across all component pairs. A depth sensitivity analysis suggests that observed velocity changes were confined to the uppermost 5 km of the subsurface. We consider strong ground motions a likely candidate for the seismic velocity decrease, followed by post-seismic relaxation via crack healing of the faults that ruptured in the Kaikoura region. Fault-zone damage may also have contributed to observed decreases in the vicinity of ruptured faults.
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Magrani, F., Valla, P. G., & Egholm, D. (2022). Modelling alpine glacier geometry and subglacial erosion patterns in response to contrasting climatic forcing. Earth Surface Processes And Landforms, 47(4), 1054–1072.
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Majstorovic, J., Giffard-Roisin, S., & Poli, P. (2022). 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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Manatschal, G., Chenin, P., Haupert, I., Masini, E., Frasca, G., & Decarlis, A. (2022). The Importance of Rift Inheritance in Understanding the Early Collisional Evolution of the Western Alps. Geosciences, 12(12).
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Manceau, A. (2022). Comment on “New insights into the biomineralization of mercury selenide nanoparticles through stable isotope analysis in giant petrel tissues”. Journal Of Hazardous Materials, 431.
Résumé: Some birds and cetaceans can demethylate the toxic methylmercury cysteinate (MeHgCys) complex into inert mercury sulfide (HgSe) through the formation of an intermediate tetrahedral selenolate complex with selenocysteine (Sec) residues (Hg(Sec)(4)). The nucleation of the HgSe biominerals involves the substitution of the Se ligand for the Sec residues, which is considered to occur in the form of multinuclear Hg-x(Se,Sec)(y) clusters mediated by proteins. Queipo-Abad et al. (2022) isolated HgSe nanoparticles from the biological tissues of giant petrels and measured the mass-dependent fractionation of the( 202)Hg isotope (delta Hg-202). They concluded that the delta Hg-202 values of the HgSe nanoparticles from each tissue of individual petrels are specific to the HgSe species alone and that the Hg(Sec)(4) -> HgSe reaction occurs without fractionation of the 202Hg isotope. We show (1) that the HgSe nanoparticles are likely mixtures of MeHgCys, Hg(Sec)(4), and HgSe, and therefore that the delta Hg-202 values are not species-specific, and (2) that the 202Hg isotope is actually fractionated during the Hg(Sec)(4) -> HgSe reaction, and therefore that this isotope can be used to trace the Hg metabolic pathways between tissues in a single individual and in different animals.
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Manceau, A., & Steinmann, S. N. (2022). Density Functional Theory Modeling of the Oxidation Mechanism of Co(II) by Birnessite. Acs Earth And Space Chemistry, 6(8), 2063–2075.
Résumé: Phyllomanganates of the birnessite family are the most abundant manganese oxides on Earth and the strongest inorganic oxidants in the environment. Birnessite controls the oxidative scavenging of cobalt in soils, lake and marine sediments, and ferromanganese crusts and nodules, leading to enrichments of the order of one billion times the concentration in solution. However, a detailed mechanistic understanding of the enrichment processes is lacking. Here, we perform density functional theory calculations to explore the mechanisms of Co(II) to Co(III) oxidation on the layer edge and surface of birnessite nanoparticles. We show that Co(II) sorption on a layer edge is an unlikely oxidation pathway. In contrast, Co(II) sorbed on a Mn(IV) vacancy site exposed on the layer surface as an octahedral triple-corner sharing (TCS) complex enters the vacancy where it is oxidized to Co(III) by a layer Mn(IV) cation, which is reduced to Mn(III). The stepwise reaction proceeds as follows. The octahedral TCS complex is transformed into a smaller tetrahedral TCS complex, allowing Co(II) to cross the surface oxygen layer and to fill the empty octahedral Mn(IV) site. When in the octahedral vacancy, Co(II) is converted from the high-spin (t(2g)(5)e(g)(2)) to the low-spin (t(2g)(6)e(g)(1)) state and the Co(II) octahedron becomes strongly distorted by the Jahn-Teller effect. Afterward, the electron exchange reaction between Mn(IV) (t(2g)(3)e(g)(0)) and Co(II) (t(2g)(6)e(g)(1)) takes place, resulting in the formation of a regular low-spin Co(III) (t(2g)(6)e(g)(0)) octahedron and a Jahn-Teller distorted high-spin Mn(III) (t(2g)(3)e(g)(1)) octahedron. These findings refine previously proposed mechanisms of Co(II) oxidation by birnessite and fill gaps in our understanding of global Co sequestration in natural systems.
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Manceau, A., Brossier, R., Janssen, S. E., & Poulin, B. A. (2022). Response to Comment on “Mercury Isotope Fractionation by Internal Demethylation and Biomineralization Reactions in Seabirds: Implications for Environmental Mercury Science”: Principles and Limitations of Source Tracing and Process Tracing with Stable Isotope Signatures. Environmental Science & Technology, 56(3), 2065–2068.
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Manceau, A., Paul, S. A. L., Simionovici, A., Magnin, V., Balvay, M., Findling, N., et al. (2022). Fossil Bioapatites with Extremely High Concentrations of Rare Earth Elements and Yttrium from Deep-Sea Pelagic Sediments. Acs Earth And Space Chemistry, .
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Manceau, A., Simionovici, A., Findling, N., Glatzel, P., Detlefs, B., Wegorzewski, A., V, et al. (2022). Crystal Chemistry of Thallium in Marine Ferromanganese Deposits. Acs Earth And Space Chemistry, 6(5), 1269–1285.
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Mao, S., Lecointre, A., van der Hilst, R. D., & Campillo, M. (2022). Space-time monitoring of groundwater fluctuations with passive seismic interferometry. Nature Communications, 13(1).
Résumé: Historic levels of drought, globally, call for sustainable freshwater management. Under pressing demand is a refined understanding of the structures and dynamics of groundwater systems. Here we present an unconventional, cost-effective approach to aquifer monitoring using seismograph arrays. Employing advanced seismic interferometry techniques, we calculate the space-time evolution of relative changes in seismic velocity, as a measure of hydrological properties. During 2000-2020 in basins near Los Angeles, seismic velocity variations match groundwater tables measured in wells and surface deformations inferred from satellite sensing, but the seismological approach adds temporal and depth resolutions for deep structures and processes. Maps of long-term seismic velocity changes reveal distinct patterns (decline or recovery) of groundwater storage in basins that are adjacent but adjudicated to water districts conducting different pumping practices. This pilot application bridges the gap between seismology and hydrology, and shows the promise of leveraging seismometers worldwide to provide 4D characterizations of groundwater and other near-surface systems. Characterization of groundwater systems is important for sustainable freshwater management. Here, the authors map the distribution of groundwater storage changes at several hundred meters below the metropolitan Los Angeles during 2000-2020, by developing a cost-effective method using ambient ground vibrations recorded by seismometers.
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Marconato, L., Leloup, P. H., Lasserre, C., Jolivet, R., Caritg, S., Grandin, R., et al. (2022). Insights on fault reactivation during the 2019 November 11, M-w 4.9 Le Teil earthquake in southeastern France, from a joint 3-D geological model and InSAR time-series analysis. Geophysical Journal International, 229(2), 758–775.
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Marrocchi, Y., Piralla, M., Regnault, M., Batanova, V., Villeneuve, J., & Jacquet, E. (2022). Isotopic evidence for two chondrule generations in CR chondrites and their relationships to other carbonaceous chondrites. Earth And Planetary Science Letters, 593.
Résumé: Among primitive meteorites, CR chondrites have peculiar isotopic compositions, the origin of which is uncertain and may have involved contributions from primordial molecular cloud material or the chondrites' formation and agglomeration late during the evolution of the protoplanetary disk. Here, we report a comprehensive textural and isotopic characterization of type I CR chondrules and provide new insights on their formation conditions. We find that two chondrule populations characterized by different sizes and oxygen isotopic compositions co-exist in CR chondrites. The typically larger, O-16-poor (delta O-17 > -4 parts per thousand) chondrules (type I-CR chondrules) appear to have formed late out of a CR reservoir already populated by typically smaller, O-16-rich (delta O-17 < -4 parts per thousand) chondrules (type I-CO chondrules). Before formation of type I-CR chondrules, the CR reservoir was likely dominated by CI-like dust, in line with the proximity of CR with CI chondrites for many isotopic ratios. The CR reservoir thus may have largely belonged to the continuum shown by other carbonaceous chondrites, although some isotopic ratios maintain some originality and suggest isotopic variation of CI-like dust in the outer disk. Combined with literature data, our data (i) demonstrates that recycling processes are responsible for the singular compositions of CR chondrites and their chondrules for isotopic systems with drastically different geochemical behaviors (O, Cr, Te) and (ii) support the homogeneous distribution of Al-26 throughout the protoplanetary disk. (c) 2022 Elsevier B.V. All rights reserved.
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Masoch, S., Fondriest, M., Gomila, R., Jensen, E., Mitchell, T. M., Cembrano, J., et al. (2022). Along-strike architectural variability of an exhumed crustal-scale seismogenic fault (Bolfin Fault Zone, Atacama Fault System, Chile). Journal Of Structural Geology, 165.
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Mathey, M., Doin, M. - P., Andre, P., Walpersdorf, A., Baize, S., & Sue, C. (2022). Spatial Heterogeneity of Uplift Pattern in the Western European Alps Revealed by InSAR Time-Series Analysis. Geophysical Research Letters, 49(1).
Résumé: The Western European Alps display measurable surface deformation rates from leveling and GNSS data. Based on the time-series analysis of 4 years of Sentinel-1 data, we propose for the first time an InSAR-based mapping of the uplift pattern affecting the Western Alps on a similar to 350 x 175-km-wide area. This approach provides a denser spatial distribution of vertical motion despite the high noise level inherent to mountainous areas and the low expected deformation signal. Our results show consistency with other geodetic measurements at the regional scale, and reveal smaller-scale spatial variations in the uplift pattern. Higher uplift rates are found within the external crystalline massifs compared to surrounding areas, in agreement with the variations expected from recent deglaciation and long-term exhumation data. This work brings the first InSAR-based geodetic clue of differential uplift within the Alpine belt in response to the surface and deep processes affecting the belt.
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Maubant, L., Radiguet, M., Pathier, E., Doin, M. - P., Cotte, N., Kazachkina, E., et al. (2022). Interseismic coupling along the Mexican subduction zone seen by InSAR and GNSS. Earth And Planetary Science Letters, 586.
Résumé: In the Mexican subduction zone, the heterogeneous spatial density of the GNSS network is limiting the capability to measure and study the variability of the surface deformation field all along the subduction zone. To improve the spatial coverage of interseismic deformation estimates, we combine InSAR and GNSS data. We use four Sentinel-1 descending tracks covering a large part of the Mexican Pacific coast from Jalisco to Oaxaca, over the period from 2016 to 2019.5. The InSAR and GNSS time series, over the same 3.5-year period, are corrected for the coseismic deformations of two M-w > 7 earthquakes but not for slow slip events (SSE) and postseismic surface displacements. We present estimates of mean surface velocities over the study period, which combine the linear inter-SSE trend and transient aseismic slip. By inverting these velocities, we estimate the short term coupling at the plate interface, which shows large lateral variations. InSAR data significantly improves the resolution of the inversion, compared to a model based only on GNSS data. Although not representative of long-term coupling in areas with large transient events, the short-term coupling estimates highlight the role of transient signals, such as slow slip events, on the coupling variability measured by geodesy. In agreement with GNSS times series over longer time period, the data also suggest that the Jalisco area (longitude from -106 degrees E to -104 degrees E), where no large transient events are observed, is highly coupled with a coupling ratio higher than 0.8. (C) 2022 Elsevier B.V. All rights reserved.
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McBeck, J., Aiken, J. M., Cordonnier, B., Ben-Zion, Y., & Renard, F. (2022). Predicting Fracture Network Development in Crystalline Rocks. Pure And Applied Geophysics, 179(1), 275–299.
Résumé: The geometric properties of fractures influence whether they propagate, arrest, or coalesce with other fractures. Thus, quantifying the relationship between fracture network characteristics may help predict fracture network development, and perhaps precursors to catastrophic failure. To constrain the relationship and predictability of fracture characteristics, we deform eight one centimeter tall rock cores under triaxial compression while acquiring in situ X-ray tomograms. The tomograms reveal precise measurements of the fracture network characteristics above the spatial resolution of 6.5 μm. We develop machine learning models to predict the value of each characteristic using the other characteristics, and excluding the macroscopic stress or strain imposed on the rock. The models predict fracture development more accurately in the experiments performed on granite and monzonite, than the experiments on marble. Fracture network development may be more predictable in these igneous rocks because their microstructure is more mechanically homogeneous than the marble, producing more systematic fracture development that is not strongly impeded by grain contacts and cleavage planes. The varying performance of the models suggest that fracture volume, length, and aperture are the most predictable of the characteristics, while fracture orientation is the least predictable. Orientation does not correlate with length, as suggested by the idea that the orientation evolves with increasing differential stress and thus fracture length. This difference between the observed and expected relationship between orientation and length highlights the influence of mechanical heterogeneities and local stress perturbations on fracture growth as fractures propagate, link, and coalesce.
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McBeck, J., Ben-Zion, Y., & Renard, F. (2022). Volumetric and shear strain localization throughout triaxial compression experiments on rocks. Tectonophysics, 822.
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McBeck, J. A., Ben-Zion, Y., Zhou, X., & Renard, F. (2022). Precursory Off-Fault Deformation in Restraining and Releasing Step Overs: Insights From Discrete Element Method Models. Journal Of Geophysical Research-Solid Earth, 127(9).
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Messager, E., Giguet-Covex, C., Doyen, E., Etienne, D., Gielly, L., Sabatier, P., et al. (2022). Two Millennia of Complexity and Variability in a Perialpine Socioecological System (Savoie, France): The Contribution of Palynology and sedaDNA Analysis. Frontiers In Ecology And Evolution, 10.
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Metivier, L., & Brossier, R. (2022). On the use of nonlinear anisotropic diffusion filters for seismic imaging using the full waveform. Inverse Problems, 38(11).
Résumé: Nonlinear anisotropic diffusion filters have been introduced in the field of image processing for image denoising and image restoration. They are based on the solution of partial differential equations involving a nonlinear anisotropic diffusion operator. From a mathematical point of view, these filters enjoy attractive properties, such as minimum-maximum principle, and an inherent decomposition of the images in different scales. We investigate in this study how these filters can be applied to help solving data-fitting inverse problems. We focus on seismic imaging using the full waveform, a well known nonlinear instance of such inverse problems. In this context, we show how the filters can be applied directly to the solution space, to enhance the structural coherence of the parameters representing the subsurface mechanical properties and accelerate the convergence. We also show how they can be applied to the seismic data itself. In the latter case, the method results in an original low-frequency data enhancement technique making it possible to stabilize the inversion process when started from an initial model away from the basin of attraction of the global minimizer. Numerical results on a 2D realistic synthetic full waveform inversion case study illustrate the interesting properties of both approaches.
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Metivier, L., & Brossier, R. (2022). Receiver-extension strategy for time-domain full-waveform inversion using a relocalization approach. Geophysics, 87(1), R13–R33.
Résumé: A receiver-extension strategy is presented as an alternative to recently promoted source-extension strategies, in the framework of high-resolution seismic imaging by full-waveform inversion (FWI). This receiver-extension strategy is directly applicable in time-domain FWI, and, unlike sourceextension methods, it incurs negligible extra computational cost. After connections between different source-extension strategies are reviewed, the receiver-extension method is introduced and analyzed for single-arrival data. The method results in a misfit function convex with respect to the velocity model in this context. The method is then applied to three exploration-scale synthetic case studies representative of different geologic environments, based on the Marmousi model, the BP 2004 salt model, and the Valhall model. In all three cases, the receiver-extension strategy makes it possible to start FWI with crude initial models and to reconstruct meaningful subsurface velocity models. The good performance of the method, even considering the inaccurate amplitude prediction due to noise, imperfect modeling, and source wavelet estimation, bodes well for field data applications.
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Mikesell, T. D., Mordret, A., Xu, Z., & Frank, W. B. (2022). Crustal Structure across the West Antarctic Rift System from Multicomponent Ambient Noise Surface Wave Tomography. Seismological Research Letters, 93(4), 2201–2217.
Résumé: Approximately 2 yr (2010???2011) of continuous seismic records from a subset of the Antarctic component of the Polar Earth Observing Network (POLENET-ANET) seismic network deployed in West Antarctica are used to compute the nine components of the correlation tensor between each pair of stations in the network. Rayleigh wave velocity information from the vertical and radial components was extracted in the form of group and phase velocity dispersion curves, whereas the transverse component provided complimentary Love wave velocity information. The multicomponent Rayleigh wave measurements (ZZ, RR, ZR, and RZ) were averaged and used to infer the measurement uncertainties. The Rayleigh and Love wave group and phase velocities were then regionalized in space using a 2D deterministic tomography. A transect that spans the West Antarctic rift system was extracted from the tomography at individual periods between 7 and 60 s for the four types of surface wave velocities (i.e., Rayleigh and Love phase and group velocities). A transdimensional Bayesian joint inversion algorithm was used to invert these four datasets for a 1D model of isotropic shear-wave velocity versus depth at each point along the transect. In this way, surface wave dispersion curves from multicomponent noise correlations were used to build a 2D isotropic shear-wave velocity model down to -55 km depth. In this model, the top of the large low-velocity zone beneath Marie Byrd Land was imaged (up to a 5% decrease in velocity at -50 km depth), which provides further evidence for a mantle hot spot beneath the crust that supports the high topography in this region. We also observed a large velocity contrast in the lower crust beneath Marie Byrd Land at a depth where previous long-period seismicity has been observed. This strong contrast occurs more shallow than in previous crustal models, which compared to our model identify a deeper Moho ( -5???10 km deeper) beneath Marie Byrd Land. This new model has implications for interpreting earthquake locations in this region and perhaps necessitates that we revisit past hypocenter estimation studies using updated velocity models for the region.
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Mikhailov, V. O., Timofeeva, V. A., Smirnov, V. B., Timoshkina, E. P., & Shapiro, N. M. (2022). New Model of the Rupture Surface of the M-w=7.8 Near Islands Aleutian Earthquake of July 17, 2017 Based on SAR Interferometry. Izvestiya-Physics Of The Solid Earth, 58(2), 230–242.
Résumé: A new model of the rupture surface of the M-w = 7.8 Near Islands Aleutian earthquake that occurred on July 17, 2017 in the region of the Commander Islands of the Aleutian Island Arc is presented. The model is based on the displacement fields obtained from Sentinel-1B radar images for the Bering and Mednyi Islands. Among the interferogram pairs calculated from the images covering the period from June 17 to August 28, 2017, the most reliable displacement fields were obtained from the image pair July 11-July 23, 2017. These displacements include coseismic and part of postseismic displacements. The inversion also involved the displacement data recorded by the GNSS GPS stations on the Kamchatka Peninsula, Commander Islands, and the closest to the epicenter Aleutian Islands. Due to the fact that displacements substantially exceeding the noise level were only recorded at two GPS stations on the Bering and Shemya islands, the use of the InSAR data substantially refines the existing earthquake source models. In our models, a seismic rupture zone is approximated by a plane with a length of 370 km along the strike and 19 km along the dip, respectively. Three models have been calculated: a model of uniform displacement across the entire rupture surface; a model in which the rupture surface is divided strikewise into five elements; and a model divided into four elements along the strike and into two levels along the dip, with a total of eight elements. All models demonstrate the same displacement type-right-lateral strike-slip faulting with a relatively small thrust component. According to the constructed models, the displacements in some areas of the rupture surface are slightly smaller than average but, generally, they occur all over the source zone. The models based on satellite geodetic data and on waveform inversion largely agree. The discrepancy between the models utilizing different data types can probably be due to the fact that seismological data characterize the part of the source process that is accompanied by the generation of seismic waves. Surface displacements estimated from InSAR data do not characterize the main event alone but also contain contributions that may reflect various creep processes. The period covered by the radar images also includes the foreshocks with magnitudes up to 6.3 as well as more than 100 aftershocks with magnitudes between 4 to 5.5. Perhaps that is why the displacements obtained in our models are more uniformly distributed over the 370-km rupture surface than in the models based on the waveform analysis.
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Mikhailova, J. A., Aksenov, S. M., Pakhomovsky, Y. A., Moine, B. N., Dusseaux, C., Vaitieva, Y. A., et al. (2022). Iron in Nepheline: Crystal Chemical Features and Petrological Applications. Minerals, 12(10).
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Milesi, G., Monie, P., Soliva, R., Muench, P., Valla, P. G., Brichau, S., et al. (2022). Deciphering the Cenozoic Exhumation History of the Eastern Pyrenees Along a Crustal-Scale Normal Fault Using Low-Temperature Thermochronology. Tectonics, 41(4).
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Minetto, R., Helmstetter, A., Schwartz, S., Langlais, M., Nomade, J., & Gueguen, P. (2022). Analysis of the Spatiotemporal Evolution of the Maurienne Swarm (French Alps) Based on Earthquake Clustering. Earth And Space Science, 9(7).
Résumé: Between August 2017 and March 2019, an intense seismic swarm was recorded in the Maurienne valley in the north of the Belledonne massif (Western French Alps). In order to study the spatiotemporal evolution of the Maurienne swarm, we created a high-resolution catalog based on template matching, double-difference relocation, and moment magnitudes. The catalog includes 71,064 events with a maximum moment magnitude of 3.5 and a magnitude of completeness of 0.7. The seismic activity is interpreted as the reactivation of an N80 strike-slip fault system called Fond de France. Moreover, earthquake relocation reveals the presence of a shallower fault system with the same strike, but opposite dip direction and smaller size. The presence of two distinct fault systems may explain the observed variation of the b-value with depth. The seismicity migrated asymmetrically in all directions during the course of about 15 months. Shorter migrations lasting 2-3 days are also observed. The different migration patterns suggest that the swarm is driven by several mechanisms, possibly pore-pressure diffusion, aseismic slip, and earthquake interactions.
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Miozzi, F., Morard, G., Antonangeli, D., Baron, M. A., Pakhomova, A., Clark, A. N., et al. (2022). The Fe-Si-C system at extreme P-T conditions: A possible core crystallization pathway for reduced planets. Geochimica Et Cosmochimica Acta, 322, 129–142.
Résumé: Several characteristics of a planet, including its internal dynamics, hinge on the composition and crystallization regime of the core, which, in turn, depends on the phase relations, melting behaviour and thermodynamic properties of constituent materials. The Fe-Si-C ternary system can serve as a proxy for core composition and formation processes under reducing conditions. We conducted laser-heated diamond anvil cell experiments coupled with in situ X-ray diffraction and electron microscopy analysis of the recovered samples, on four different starting compositions in the Fe-Si-C ternary system. Phase relations up to 200 GPa and up to 4000 K were determined. An FeSi phase with a B2 structure and iron carbides with different stoichiometries (i.e., Fe3C and Fe7C3) are the main observed phases, along with pure C (diamond) that has an extended stability field in the subsolidus regime. Carbon is largely soluble in B2-structured FeSi, whereas Si does not partition into the carbides. The melting curve determined for the starting material containing the least amount of light elements is consistent with the one for the Fe-C system. The other starting materials display higher melting temperatures than that of Fe-C, suggesting the existence of at least two different invariant points in the Fe-Si-C system. Applied to planetary interiors, our observations highlight how a small variation in light elements content would deeply affect the solidification style of a core. Bottom-up (Fe-enriched systems) and top-down regimes (C-rich systems), as well as solidification of a crystal mush (Si-enriched systems). These three crystallization regimes influence significantly the possibility of starting and sustaining a dynamo. Our results provide new insights into the differentiation of terrestrial planets in the Solar System and beyond, contributing to the study of planetary diversity. (C) 2022 Elsevier Ltd. All rights reserved.
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Mishra, M., Besancon, G., Chambon, G., & Baillet, L. (2022). Calculus of variations for estimation in ODE-PDE landslide-like models with discrete-time asynchronous measurements. International Journal Of Control, .
Résumé: Motivated by some landslide models, and related estimation challenges, this paper presents an optimal estimation method for state and parameter in a special class of so-called ODE-PDE system based on the adjoint method for discrete-time asynchronous measurements. This system is described by a pair of coupled Ordinary Differential Equation (ODE) and Partial Differential Equation (PDE), with a mixed boundary condition for the PDE. The coupling appears both in the ODE and in the Neuman boundary condition of the PDE. For this system, initial conditions or state variables and some empirical parameters are assumed to be unknown and need to be estimated. The Lagrangian multiplier method is used to connect the dynamics of the system and the cost function defined as the least square error between the simulation values and the available measurements. The adjoint state method is applied to the objective functional to get the adjoint system and the gradients with respect to parameters and initial state. The cost functional is optimised, employing the steepest descent method to estimate parameters and initial state. This general approach is illustrated by two application examples corresponding to two different landslide models that validate the presented optimal estimation approach. The first one is about state and parameter estimation in an extended sliding-consolidation landslide model, and the second one is in the viscoplastic sliding-consolidation landslide model.
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Molnar, S., Sirohey, A., Assaf, J., Bard, P. - Y., Castellaro, S., Cornou, C., et al. (2022). A review of the microtremor horizontal-to-vertical spectral ratio (MHVSR) method. Journal Of Seismology, 26(4), 653–685.
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Monasterio-Guillot, L., Crespo-Lopez, L., Rodriguez Navarro, A. B., & Alvarez-Lloret, P. (2022). Comparative Study of the Mineralogy and Chemistry Properties of Elephant Bones: Implications during Diagenesis Processes. Minerals, 12(11).
Résumé: Elephants are currently the largest terrestrial mammals, along with their extinct ancestor the mammoth. These species are of great interest due to their geographic distribution and ecological importance. However, the bone mineral characteristics of their skeleton as well as their alteration during burial processes over millions of years have been poorly investigated. In the current research, we analyzed the compositional and structural mineral properties of different types (i.e., long and flat bones) of elephant and mammoth bones. For this purpose, we performed a comparative study between these bone types using complementary analytical techniques based on X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, and inductively coupled plasma spectroscopic analysis. The chemical composition of the samples shows a relative loss of a considerable percentage of water and organic matter components for the fossilized bone, accompanied by a higher bone mineralization degree and the presence of other crystalline phases (i.e., calcite and pyrite) related to a certain degree of diagenesis alteration. Our results also show a variation in the crystalline properties of mammoth bone related to the recrystallization process during the dissolution-precipitation transformation through diagenetic burial. This research provides relevant information for understanding the mineral properties of different types of bones and their possible changes during diagenesis.
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Mora, A., Delgado, H. G., Villamizar-Escalante, N., Bermudez, M. A., Bernet, M., & Velandia, F. (2022). Climate or tectonics? What controls the spatial-temporal variations in erosion rates across the Eastern Cordillera of Colombia? [Global and planetary change, volume 203, August 2021, 103,541]: Comment and reply. Global And Planetary Change, 214.
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Mora, M. M., Lesage, P., Taylor-Castillo, W., Vergniolle, S., Fourel, L., & Soto, G. J. (2022). Evolution and dynamics of the open-vent eruption at Arenal volcano (Costa Rica, 1968-2010): what we learned and perspectives. Bulletin Of Volcanology, 84(7).
Résumé: On 29 July 1968, there was a violent reactivation of Arenal volcano. The resulting westward-directed lateral blast eruption left two villages destroyed and 78 people dead. The activity continued as a long-lasting, open-vent eruption that evolved into seven recognisable phases reflecting changes in magma supply, explosive activity and cone evolution, and ended in October 2010. Here, we review this activity, the geophysical approaches applied to understanding it and the open questions resulting from these insights. The eruptive dynamics were characterised by almost constant lava effusion, degassing, strombolian and vulcanian explosions and infrequent pyroclastic density currents. In this study, the total rock dense equivalent volume of lava and tephra erupted is calculated at 757+77 Mm(3), while the volume of the lava flow field is 527 +/- 58 Mm(3). Typical seismic activity included harmonic and spasmodic tremors, long-period events and explosion signals with frequent audible “booms”. The decline of the eruptive activity started in 2000, with a decrease in the number and size of explosive events, a shift from long to short lava flows along with the collapse of lava flow fronts and the subsequent formation of downward-rolling lava block aprons, the frequent growth of dome-like structures on the summit and a gradual decrease in seismic energy. Multiple geological and geophysical studies during this 42-year-long period of open-vent activity at Arenal resulted in many advances in understanding the dynamics of andesitic blocky lava flows, the origin and diversity of pyroclastic density currents and seismic sources, as well as the role of site effects and rough topography in modifying the seismic wavefield. The acoustic measurements presented here include two types of events: typical explosions and small pressure transients. Features of the latter type are not usually observed at volcanoes with intermediate to evolved magma composition. Explosions have different waveforms and larger gas volumes than pressure transients, both types being associated with active and passive degassing, respectively. This body of data, results and knowledge can inform on the type of activity, and associated geophysical signals, of open-vent systems that are active for decades.
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Morard, G., Antonangeli, D., Bouchet, J., Rivoldini, A., Boccato, S., Miozzi, F., et al. (2022). Structural and Electronic Transitions in Liquid FeO Under High Pressure. Journal Of Geophysical Research-Solid Earth, 127(11).
Résumé: FeO represents an important end-member for planetary interiors mineralogy. However, its properties in the liquid state under high pressure are poorly constrained. Here, in situ high-pressure and high-temperature X-ray diffraction experiments, ab initio simulations, and thermodynamic calculations are combined to study the local structure and density evolution of liquid FeO under extreme conditions. Our results highlight a strong shortening of the Fe-Fe distance, particularly pronounced between ambient pressure and similar to 40 GPa, possibly related with the insulator to metal transition occurring in solid FeO over a similar pressure range. Liquid density is smoothly evolving between 60 and 150 GPa from values calculated for magnetic liquid to those calculated for non-magnetic liquid, compatibly with a continuous spin crossover in liquid FeO. The present findings support the potential decorrelation between insulator/metal transition and the high-spin to low-spin continuous transition, and relate the changes in the microscopic structure with macroscopic properties, such as the closure of the Fe-FeO miscibility gap. Finally, these results are used to construct a parameterized thermal equation of state for liquid FeO providing densities up to pressure and temperature conditions expected at the Earth's core-mantle boundary.
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Morena, P., Ratzov, G., Cattaneo, A., Klingelhoefer, F., Beck, C., Seibert, C., et al. (2022). Coexistence of Adjacent Siliciclastic, Carbonate, and Mixed Sedimentary Systems: An Example From Seafloor Morphology in the Northern Lesser Antilles Forearc. Frontiers In Earth Science, 10.
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Mourey, J., Lacroix, P., Duvillard, P. - A., Marsy, G., Marcer, M., Malet, E., et al. (2022). Multi-method monitoring of rockfall activity along the classic route up Mont Blanc (4809 m a.s.l.) to encourage adaptation by mountaineers. Natural Hazards And Earth System Sciences, 22(2), 445–460.
Résumé: There are on average 35 fatal mountaineering accidents per summer in France. On average, since 1990, 3.7 of them have occurred every summer in the Grand Couloir du Gouter, on the classic route up Mont Blanc (4809 m a.s.l.). Rockfall is one of the main factors that explain this high accident rate and contribute to making it one of the most accident-prone areas in the Alps for mountaineers. In this particular context, the objective of this study is to document the rockfall activity and its triggering factors in the Grand Couloir du Gouter in order to disseminate the results to mountaineers and favour their adaptation to the local rockfall hazard. Using a multi-method monitoring system (five seismic sensors, an automatic digital camera, three rock subsurface temperature sensors, a traffic sensor, a high-resolution topographical survey, two weather stations and a rain gauge), we acquired a continuous database on rockfalls during a period of 68 d in 2019 and some of their potential triggering factors (precipitation, ground and air temperatures, snow cover, frequentation by climbers). At the seasonal scale, our results confirm previous studies showing that rockfalls are most frequent during the snowmelt period in permafrost-affected rockwalls. Furthermore, the unprecedented time precision and completeness of our rockfall database at high elevation thanks to seismic sensors allowed us to investigate the factors triggering rockfalls. We found a clear correlation between rockfall frequency and air temperature, with a 2 h delay between peak air temperature and peak rockfall activity. A small number of rockfalls seem to be triggered by mountaineers. Our data set shows that climbers are not aware of the variations in rockfall frequency and/or cannot/will not adapt their behaviour to this hazard. These results should help to define an adaptation strategy for climbers. Therefore, we disseminated our results within the mountaineering community thanks to the full integration of our results into the management of the route by local actors. Knowledge built during this experiment has already been used for the definition and implementation of management measures for the attendance in summer 2020.
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Moya, A., Aleman, J., Gomez-Herrero, J., Mas-Balleste, R., & de Pablo, P. J. (2022). Nanotribology and electrical properties of carbon nanotubes hybridized with covalent organic frameworks. Carbon, 199, 80–86.
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Mreyen, A. - S., Donati, D., Elmo, D., Donze, F. V., & Havenith, H. - B. (2022). Dynamic numerical modelling of co-seismic landslides using the 3D distinct element method: Insights from the Balta rockslide (Romania). Engineering Geology, 307.
Résumé: Ancient landslides of unknown origin can be found in large numbers in mountainous regions; some represent valid markers of (pre-)historic natural regimes referring to either long-term evolution or short-term peak events of climatic and seismotectonic nature. An example is represented by the Balta rockslide in the Romanian Car-pathian Mountains. Its location in the seismically active Vrancea-Buzau region, as well as its morphological features, deep-seated rupture surface and large debris volume, raise the question of its failure history with regard to a possible co-seismic triggering. A 3D volume based reconstruction of the slope morphology together with field measurements of elasto-plastic in-situ rock properties allow to estimate pre-failure conditions of the slope, with special regards to the geological, i.e. flysch bedrock of poor to fair rock quality, and structural settings, i.e. anti -dip slope bedding crossed by the main joint family. The reconstructed slope behaviour was tested under static and dynamic forces with the 3D distinct element code 3DEC, subsequently used to simulate a failure scenario with a 120 s long real earthquake record that leads to the realistic post-failure morphology of Balta. For the latter, we observe a principally joint-controlled failure combined with internal fracturing of the undamaged rock mass. After 230 s of simulated time, the landslide debris reaches the valley bottom with maximum displacements of 1350 m and is marked by a lateral expansion to a broader extent than the source zone width, as observed in the field. Extension of this work to other pre-historic slope failures in the valleys of Vrancea-Buzau yield valuable new information for future seismic hazard estimations of the region.
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Muller, V. A. P., Sternai, P., Sue, C., Simon-Labric, T., & Valla, P. G. (2022). Climatic control on the location of continental volcanic arcs. Scientific Reports, 12(1).
Résumé: Orogens and volcanic arcs at continental plate margins are primary surface expressions of convergent plate tectonics. Although it is established that climate affects the shape, size, and architecture of orogens via orographic erosion gradients, the ascent of magma through the crust and location of volcanoes along magmatic arcs have been considered insensitive to erosion. However, available data reveal westward migration of late-Cenozoic volcanic activity in the Southern Andes and Cascade Range where orography drives an eastward migration of the topographic water divide by increased precipitation and erosion along west-facing slopes. Thermomechanical numerical modeling shows that orographic erosion and the associated leeward topographic migration may entail asymmetric crustal structures that drive the magma ascent toward the region of enhanced erosion. Despite the different tectonic histories of the Southern Andes and the Cascade Range, orographic erosion is a shared causal mechanism that can explain the late-Cenozoic westward migration of the volcanic front along both magmatic arcs.
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Nanni, U., Roux, P., Gimbert, F., & Lecointre, A. (2022). Dynamic Imaging of Glacier Structures at High-Resolution Using Source Localization With a Dense Seismic Array. Geophysical Research Letters, 49(6).
Résumé: Dense seismic array monitoring combined with advanced processing can help retrieve and locate a variety of seismic sources with unprecedented resolution and spatial coverage. We present a methodology that goes beyond classical localization algorithms through gathering various types of sources (impulsive or continuous) using a single scheme based on a gradient-descent optimization and evaluating different levels of phase coherence. We apply our methodology on an Alpine glacier and demonstrate that we can retrieve the dynamics of active crevasses with a metric resolution using sources associated with high phase coherence; the presence of diffracting materials (e.g., rocks) trapped in transverse crevasses using sources with moderate phase coherence; and the two-dimensional time evolution of the subglacial hydrology system using sources with low phase coherence. Our study highlights the strength of using an appropriate and systematic seismological approach to image a wide range of subsurface structures and phenomena in settings with complex wavefields.
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Nataf, H. - C. (2022). Tidally Synchronized Solar Dynamo: A Rebuttal. Solar Physics, 297(8).
Résumé: The idea of a planetary origin for the solar cycle dates back to the nineteenth century. Despite unsurmounted problems, it is still advocated by some. Stefani, Giesecke, and Weier (Solar Phys. 294, 60, 2019) thus recently proposed a scenario based on this idea. A key argument they put forward is evidence that the approximate to 11 years solar cycle is “clocked”, as if it were paced by an accurate clock inside the Sun. Their demonstration rests upon the computation of a ratio proposed by Dicke (Nature 276, 676, 1978) applied to the solar-cycle time series of Schove (J. Geophys. Res. 60, 127, 1955). I show that their demonstration is invalid, because the assumptions used by Schove to build his time series force a clocked behavior. I also show that instabilities in a magnetized fluid can produce fluctuation time series that are close to being clocked.
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Natalini, D., Ganau, M., Rosenkranz, R., Petrinic, T., Fitzgibbon, K., Antonelli, M., et al. (2022). Comparison of the Asleep-Awake-Asleep Technique and Monitored Anesthesia Care During Awake Craniotomy: A Systematic Review and Meta-analysis. Journal Of Neurosurgical Anesthesiology, 34(1), E1–E13.
Résumé: Awake craniotomy (AC) is the preferred surgical option for intractable epilepsy and resection of tumors adjacent to or within eloquent cortical areas. Monitored anesthesia care (MAC) or an asleep-awake-asleep (SAS) technique is most widely used during AC. We used a random-effects modeled meta-analysis to synthesize the most recent evidence to determine whether MAC or SAS is safer and more effective for AC. We included randomized controlled trials and observational studies that explored the incidence of AC failure, duration of surgery, and hospital length of stay in adult patients undergoing AC. Eighteen studies were included in the final analysis. MAC was associated with a lower risk of AC failure when compared with SAS (global pooled proportion MAC vs. SAS 1% vs. 4%; odds ratio [ORs]: 0.28; 95% confidence interval [CI]: 0.11-0.71; P = 0.007) and shorter surgical procedure time (global pooled mean MAC vs. SAS 224.44 vs. 327.94 min; mean difference, -48.76 min; 95% CI: -61.55 to -35.97; P < 0.00001). SAS was associated with fewer intraoperative seizures (global pooled proportion MAC vs. SAS 10% vs. 4%; OR: 2.38; 95% CI: 1.05-5.39; P = 0.04). There were no differences in intraoperative nausea and vomiting between the techniques (global pooled proportion MAC vs. SAS: 4% vs. 8%; OR: 0.86; 95% CI: 0.30-2.45; P = 0.78). Length of stay was shorter in the MAC group (MAC vs. SAS 3.96 vs. 6.75 days; mean difference, -1.30; 95% CI: -2.69 to 0.10; P = 0.07). In summary, MAC was associated with lower AC failure rates and shorter procedure time compared with SAS, whereas SAS was associated with a lower incidence of intraoperative seizures. However, there was a high risk of bias and other limitations in the studies included in this review, so the superiority of 1 technique over the other needs to be confirmed in larger randomized studies.
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Noiriel, C., & Renard, F. (2022). Four-dimensional X-ray micro-tomography imaging of dynamic processes in geosciences. Comptes Rendus Geoscience, 354, 255–280.
Résumé: The dynamic response of rocks to thermal, hydrodynamical, mechanical, and geochemical solicitations is of fundamental interest in several disciplines of geosciences, including geoengineering, geophysics, rock physics, hydrology, mineralogy, and environmental and soil sciences. From crystal shape to rock microstructure or pore space and fluid distribution, parameters characterizing the rock physico-chemical properties evolve at different time and spatial scales. X-ray micro-tomography (XMT), as a non-invasive and non-destructive imaging technique, offers an unprecedented opportunity to add the fourth dimension, i.e. time, to the three-dimensional spatial visualization of rock and mineral microstructures. The technique is increasingly used to explore dynamic processes in porous and fractured rocks, thanks to synchrotron sources and laboratory XMT scanners, new generations of detectors, and increasing computational power. Image processing allows for tracking the evolution of the fluid-fluid or fluid-mineral interfaces as well as measuring incremental deformations, as rocks deform and react through time under in situ conditions of the sub-surface. Here, we review recent advances in 4D X-ray micro-tomography applied to thermo-hydro-mechano-chemical (THMC) sub-surface processes where fluids, porosity, minerals, and rock microstructures evolve together.
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Nouibat, A., Stehly, L., Paul, A., Schwartz, S., Bodin, T., Dumont, T., et al. (2022). Lithospheric transdimensional ambient-noise tomography of W-Europe: implications for crustal-scale geometry of the W-Alps. Geophysical Journal International, 229(2), 862–879.
Résumé: A full understanding of the dynamics of mountain ranges such as the Alps requires the integration of available geological and geophysical knowledge into a lithospheric-scale 3-D geological model. As a first stage in the construction of this geo-model, we derive a new 3-D shear wave velocity model of the Alpine region, with a spatial resolution of a few tens of kilometres, making it possible to compare with geological maps. We use four years of continuous vertical-component seismic noise records to compute noise correlations between more than 950 permanent broad-band stations complemented by similar to 600 temporary stations from the AlpArray sea-land seismic network and the Cifalps and EASI linear arrays. A specific pre-processing is applied to records of ocean-bottom seismometers in the Liguro-Provencal basin to clean them from instrumental and oceanic noises. We first perform a 2-D transdimensional inversion of the traveltimes of Rayleigh waves to compute group-velocity maps from 4 to 150 s. The data noise level treated as an unknown parameter is determined with a Hierarchical Bayes method. A Fast Marching Eikonal solver is used to update ray path geometries during the inversion. We use next the group-velocity maps and their uncertainties to derive a 3-D probabilistic V-s model. The probability distributions of V-s at depth and the probability of presence of an interface are estimated at each location by exploring a set of 130 million synthetic four-layer 1-D V-s models. The obtained probabilistic model is refined using a linearized inversion. Throughout the inversion for V-s, we include the water column where necessary. Our V-s model highlights strong along-strike changes of the lithospheric structure, particularly in the subduction complex between the European and Adriatic plates. In the South-Western Alps, our model confirms the existence of a low-velocity structure at 50 – 80 km depth in the continuation of the European continental crust beneath the subduction wedge. This deep low-velocity anomaly progressively disappears towards the North-Western and Central Alps. The European crust includes lower crustal low-velocity zones and a Moho jump of similar to 8 – 12 km beneath the western boundary of the External Crystalline Massifs of the North-Western Alps. The striking fit between our V-s model and the receiver function migrated depth section along the Cifalps profile documents the reliability of the V-s model. In light of this reliability and with the aim to building a 3-D geological model, we re-examine the geological structures highlighted along the Cifalps profile.
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Nouibat, A., Stehly, L., Paul, A., Schwartz, S., Rolland, Y., Dumont, T., et al. (2022). Ambient-Noise Tomography of the Ligurian-Provence Basin Using the AlpArray Onshore-Offshore Network: Insights for the Oceanic Domain Structure. Journal Of Geophysical Research-Solid Earth, 127(8).
Résumé: We derive a three-dimensional shear-wave velocity model of the Ligurian-Provence back-arc basin (Northwestern Mediterranean Sea) using ocean-bottom seismometers (AlpArray OBSs) and land stations from permanent and temporary seismic networks. The quality of OBS continuous records is enhanced by a specific processing that reduces instrumental and seabed-induced noises (transients, tilt, compliance). To further improve the resolution of ambient-noise tomography in the offshore area, we compute the Rayleigh-wave part of the Green functions for OBS-OBS pairs by using onshore stations as virtual sources. 2-D group-velocity maps and their uncertainties are computed in the 4-150 s period range by a transdimensional inversion of Rayleigh-wave travel times. The dispersion data and their uncertainties are inverted for a probabilistic 3-D shear-wave velocity model that includes probability densities for V-s and for the depth of layer interfaces. The probabilistic model is refined by a linearized inversion that accounts for the water layer in the Ligurian Sea. Our S-wave velocity and layer boundary probability models correspond well to a recent, high-resolution P-wave velocity cross-section derived from controlled-source seismic profiling along the Ligurian-Provence basin axis. A joint interpretation of the P- and S-wave velocity sections along this profile reveals a thin, anomalous oceanic crust of low P-wave velocities but high S-wave velocities, intruded by a gabbroic body. The illuminated part of the upper mantle appears to be devoid of serpentinization.
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Olason, E., Boutin, G., Korosov, A., Rampal, P., Williams, T., Kimmritz, M., et al. (2022). A New Brittle Rheology and Numerical Framework for Large-Scale Sea-Ice Models. Journal Of Advances In Modeling Earth Systems, 14(8).
Résumé: We present a new brittle rheology and an accompanying numerical framework for large-scale sea-ice modeling. This rheology is based on a Bingham-Maxwell constitutive model and the Maxwell-Elasto-Brittle (MEB) rheology, the latter of which has previously been used to model sea ice. The key strength of the MEB rheology is its ability to represent the scaling properties of simulated sea-ice deformation in space and time. The new rheology we propose here, which we refer to as the brittle Bingham-Maxwell rheology (BBM), represents a further evolution of the MEB rheology. It is developed to address two main shortcomings of the MEB rheology and numerical implementation we were unable to address previously: excessive thickening of the ice in model runs longer than about one winter and a relatively high computational cost. In the BBM rheology and numerical framework these shortcomings are addressed by demanding that the ice deforms under convergence in a purely elastic manner when internal stresses lie below a given compressive threshold. Numerical performance is improved by introducing an explicit scheme to solve the ice momentum equation. In this paper, we introduce the new rheology and numerical framework. Using an implementation of BBM in version two of the neXtSIM sea-ice model (neXtSIMv2), we show that it gives reasonable long term evolution of the Arctic sea-ice cover and very good deformation fields and statistics compared to satellite observations. Plain Language Summary Sea ice movement is determined by the wind and ocean currents acting on it, and how the ice itself reacts to these forces. In a sea-ice model this reaction is simulated with equations collectively referred to as a rheology. In this paper we introduce a new rheology, called the brittle Bingham-Maxwell (BBM) rheology, and a method for solving the equations on a computer. This new rheology extends the Maxwell-Elasto-Brittle (MEB) rheology we used in previous versions of our sea-ice model, neXtSIM. We used MEB in neXtSIM because this rheology gives a very good description of how the ice reacts to winds and currents, but we found two main faults with it we couldn't fix: the ice in the model would pile up to become unrealistically thick after several model years, and the model required too much computer time to run. In the BBM rheology we add an extra term to the MEB equations to prevent the excessive piling up of ice, and we also propose a more efficient way to solve the equations. Like its predecessor, the new rheology also allows our model to simulate very well the way the ice moves on daily basis, when compared to satellite observations.
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Ostorero, L., Balcone-Boissard, H., Boudon, G., Shapiro, N. M., Belousov, A., Belousova, M., et al. (2022). Correlated petrology and seismicity indicate rapid magma accumulation prior to eruption of Kizimen volcano, Kamchatka. Communications Earth & Environment, 3(1).
Résumé: The increase in number and intensity of earthquakes during a pre-eruptive crisis is the main basis of seismic volcano monitoring. However, a strong understanding of how these seismic signals relate to magmatic processes in the magma plumbing systems prior to volcanic eruptions is crucial for these efforts. Here we compare the characteristics of a seismo-volcanic crisis prior to the 2010-2013 explosive-extrusive eruption of Kizimen volcano, Kamchatka with the timescales of processes in the magma plumbing system. These timescales are inferred from the numerical modelling of iron-magnesium intracrystalline interdiffusion in 88 zoned orthopyroxene crystals from dacites and silica-rich andesites collected after the eruption. We find that the eruptible magmas were assembled rapidly during a magma mixing process beginning around 1.5 years before the eruption, which is well correlated with the onset of the seismic crisis. We conclude that the observed seismic re-activation marked the onset of magma mixing and led to destabilization of the reservoir, followed by the eruption. Rapid magma mixing and destabilization prior to eruption can be recorded by correlating timescales of crystal diffusion and seismicity, according to a petrological study of Kizimen volcano, Russia
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Padron, C., Klingelhoefer, F., Roest, W. R., Graindorge, D., Loncke, L., Basile, C., et al. (2022). Volcanic influence during the formation of a transform marginal plateau: Insights from wide-angle seismic data along the northwestern Demerara Plateau. Tectonophysics, 842.
Résumé: Transform marginal plateaus (TMPs) are submarine seafloor highs located at the continental slope, often at the boundary of two ocean basins of different ages and associated to at least one transform or highly oblique margin. The systematic study of TMPs can, therefore, answer questions about rifting and continental margin development. The Demerara TMP (offshore Suriname and French Guiana) is located at the border between the Central Atlantic, which opened during the Lower Jurassic and the Equatorial Atlantic, which opened during the Lower Cretaceous. This study, based on wide-angle seismic data modeling from the northern and western section of the Demerara Plateau, provides information on both the lower volcanic unit of this TMP and the adjacent oceanic crust. The results confirm that the crust of the Demerara Plateau is around 30 km thick and consists of lava flows possibly mixed with crust of continental origin in its deeper layers. Seismic velocities (exceeding 7 km/s) are compatible with those of volcanic oceanic plateaus. To the west, a relatively wide transition zone separates the plateau from the Jurassic oceanic crust, which is composed of two layers, and is much thicker than normal oceanic crust (similar to 11 km). During the Cretaceous, the plateau was sharply cut by transform and highly oblique structures, separating the Demerara Plateau from its transform conjugate, the Guinea Plateau. As a result, the Demerara Plateau is flanked to the north by a magma-poor/strongly tectonized Cretaceous oceanic domain with thin (2-3 km) crust, likely partially consisting of serpentinized mantle. In contrast, the oceanic crust located towards the south-east appears to be more characteristic of typical oceanic crust in composition though slightly thinner than normal (4-6 km) thickness. Our analysis allows us to propose a new 3D vision of the crustal structure of the Demerara TMP and its borders.
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Pasten-Araya, F., Potin, B., Azua, K., Saez, M., Aden-Antoniow, F., Ruiz, S., et al. (2022). Along-Dip Segmentation of the Slip Behavior and Rheology of the Copiapo Ridge Subducted in North-Central Chile. Geophysical Research Letters, 49(4).
Résumé: We studied the along-dip influence of the Copiapo ridge subduction in the Atacama region, North-Central Chile by building a new seismicity catalog, including similar events and non-volcanic tremors (NVTs). We also obtained a 3-D tomographic model for P and S-waves velocity (and the implied Vp/Vs ratio). We identify along-dip segmentation involving four distinct segments: a locked seismogenic zone hosting ordinary seismicity and clusters of similar events; a transition zone with NVTs and low seismicity; an aseismic zone with slow-slip events; and a deep zone with abundant intraslab seismicity. The velocity models show differences among these zones, with low velocity anomalies of Vp and Vs coinciding with aseismic slip zones, indicating the possible presence of fluids. Due to the spatial distribution along-strike and along-dip of the aseismic zones, we propose that these differences in seismogenic behavior are generated by subduction of the heterogeneous seamounts associated with the Copiapo ridge.
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Pate, A., Farge, G., Holtzman, B. K., Barth, A. C., Poli, P., Boschi, L., et al. (2022). Combining audio and visual displays to highlight temporal and spatial seismic patterns. Journal On Multimodal User Interfaces, 16(1), 125–142.
Résumé: Data visualization, and to a lesser extent data sonification, are classic tools to the scientific community. However, these two approaches are very rarely combined, although they are highly complementary: our visual system is good at recognizing spatial patterns, whereas our auditory system is better tuned for temporal patterns. In this article, data representation methods are proposed that combine visualization, sonification, and spatial audio techniques, in order to optimize the user's perception of spatial and temporal patterns in a single display, to increase the feeling of immersion, and to take advantage of multimodal integration mechanisms. Three seismic data sets are used to illustrate the methods, covering different physical phenomena, time scales, spatial distributions, and spatio-temporal dynamics. The methods are adapted to the specificities of each data set, and to the amount of information that the designer wants to display. This leads to further developments, namely the use of audification with two time scales, the switch from pure audification to time-modulated noise, and the switch from pure audification to sonic icons. First user feedback from live demonstrations indicates that the methods presented in this article seem to enhance the perception of spatio-temporal patterns, which is a key parameter to the understanding of seismically active systems, and a step towards apprehending the processes that drive this activity.
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Paul, A., Malusa, M. G., Solarino, S., Salimbeni, S., Eva, E., Nouibat, A., et al. (2022). Along-strike variations in the fossil subduction zone of the Western Alps revealed by the CIFALPS seismic experiments and their implications for exhumation of (ultra-) high-pressure rocks. Earth And Planetary Science Letters, 598.
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Pedersen, H. A., Mattern, F., Poli, P., & Stehly, L. (2022). 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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Pepin, K. S., Ellsworth, W. L., Sheng, Y., & Zebker, H. A. (2022). Shallow Aseismic Slip in the Delaware Basin Determined by Sentinel-1 InSAR. Journal Of Geophysical Research-Solid Earth, 127(2).
Résumé: The Delaware Basin, Texas is currently a hot-spot of induced seismicity and ground deformation due to fluid extraction and injection associated with horizontal drilling techniques; however, the driving mechanism behind the seismicity and deformation remains under debate. Using vertical and east-west horizontal surface deformation measurements derived from Sentinel-1 interferometric synthetic aperture radar (InSAR), we show that the subsurface responds differently to oil and gas activity in the northern and southeastern portions of the basin. In the north, where there is little seismicity, deformation patterns display long-wavelengths and equidimensional patterns. In contrast, the southeast region hosts most of the seismicity and displays spatial deformation patterns with narrow linear features that strike parallel to the maximum principal horizontal stress and to trends in seismicity, suggesting movement along normal faults. We model a linear deformation feature using edge dislocations and show that the InSAR observations can be reproduced by slip on normal faults contained within the Delaware Mountain Group (DMG), the formation that hosts local wastewater injection and the majority of earthquakes. Our model consists of three parallel, high-angle normal faults, with two dipping toward one another in a graben structure. Slip magnitudes reach up to 25 cm and are spatially correlated with injection wells. Measured seismicity can only explain similar to 2% of the fault motion predicted by our fault model, suggesting that slip leading to the deformation is predominantly aseismic. We conclude that seismic and aseismic fault motion in the southeastern Delaware Basin is likely driven by wastewater injection near critically-stressed normal faults within the DMG.
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Periollat, A., Radiguet, M., Weiss, J., Twardzik, C., Amitrano, D., Cotte, N., et al. (2022). Transient Brittle Creep Mechanism Explains Early Postseismic Phase of the 2011 Tohoku-Oki Megathrust Earthquake: Observations by High-Rate GPS Solutions. Journal Of Geophysical Research-Solid Earth, 127(8).
Résumé: The early stage of the postseismic phase is characterized by a large deformation rate. Its analysis is thus key to decipher the role played by different mechanisms (afterslip and viscoelasticity) at various time scales. Here, we process GPS data to obtain 30-s kinematic position time series recording the surface deformation following the M-w 9.0 Tohoku-Oki megathrust earthquake (2011), and combine them with static solutions over 9 years. We analyze the temporal evolution of the time series and use these observations to image the postseismic slip. We find that the first month of deformation following Tohoku-Oki can be explained by an afterslip mechanism, that exhibits an “Omori-like” decay, with a p-value around 0.75 almost everywhere with the exception of a small region around Ibaraki prefecture where p similar to 1 is observed. This p < 1 indicates that the postseismic displacements do not increase logarithmically with time as predicted by rate-and-state rheology. Instead, we argue that early afterslip is associated with a transient brittle creep mechanism. We use numerical simulations to show that an exponent of p < 1 can be explained by a combination of thermal activation of local slips and elastic interactions. Over longer time scales, an additional mechanism is required to explain the observed deformation signal, and the transient brittle creep mechanism is combined with viscoelastic relaxation modeled by a Newtonian flow. The spatial analysis reveals two distinct afterslip regions, a major one on the North, associated with a p-value around 0.75, and a smaller one close to the Ibaraki aftershock, associated with p similar to 1.
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Permana, T., Nishimura, T., Nakahara, H., & Shapiro, N. (2022). Classification of volcanic tremors and earthquakes based on seismic correlation: application at Sakurajima volcano, Japan. Geophysical Journal International, 229(2), 1077–1097.
Résumé: Classification of volcanic tremors and earthquakes is an important part of volcano monitoring. Conventional classification technique relies on visual characterization of the amplitudes, frequency, or duration of seismic signals. In some cases, such classification is difficult to be maintained continuously, especially during high eruptive activities. In the present study, we develop a classification technique based on analyses of seismic wave correlation. The technique is based on a measure of spatial coherence using the distribution width of eigenvalues from the seismic covariance matrix that is referred to as 'spectral width'. We use the spectral width characteristics to extract the frequencies where the seismic signals are the most spatially coherent. We analyse 6-month continuous seismic data at six seismic stations deployed on Sakurajima volcano, Japan. The classification is performed every 10 min to recognize volcanic tremor and B-type earthquakes, both of which show unclear onsets and are dominant at around 1-4 Hz. Their frequencies of high spatial coherence are different from each other, providing a basis for automatic classification of both types of seismic events. Our classification results show that an increase in seismic activity, particularly volcanic tremors, occurred during high eruptive activity and is well matched with the events that are routinely determined by the Japan Meteorological Agency (JMA) based on visual examination of the data. We discuss the volcanic activities by combining our classification results with those from detections and location methods based on seismic correlation. Most of the source locations of volcanic tremor and B-type earthquakes are distributed at the same region with depths of less than 4 km beneath the active craters, which are almost consistent with the source locations of explosion earthquakes and B-type earthquakes determined from P-wave onsets in the previous studies. Also, the distribution of horizontal locations is spatially elongated at shallow depths above a dyke that is inferred to extend from Aira caldera at a depth of 7-9 km. We obtain deep and shallow sources for the tremor that occurred before and after an explosive eruption, respectively. We also obtain shallow sources beneath the active crater during a continuous tremor that accompanies increasing eruptive activity. The source locations of the classified volcanic tremor and B-type earthquakes may represent the movement of magma and gas from the shallow magma chamber at 5 km depth to the active craters.
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Pimentel, C., de la Luz, A. P., Hernadez-Laguna, A., & Sainz-Diaz, C. I. (2022). Effects of the cation ordering in Mg:Al and Zn:Al layered double hydroxides on crystallographic and spectroscopical properties by means of first principles calculations. Applied Clay Science, 223.
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Pimentel, C., Hernandez-Laguna, A., & Ignacio Sainz-Diaz, C. (2022). Effect of Iron Isomorphic Substitution in Mg:Al and Zn:Al-Layered Double-Hydroxide Structures by Means of First Principle Calculations. Acs Earth And Space Chemistry, 6(10), 2499–2507.
Résumé: Layered double hydroxides (LDHs) are important components in terrestrial and extra-terrestrial environments. The presence of iron in these minerals provides them a wide potential application in environmental and materials sciences. In this work, the role of Fe in the crystallographic properties of LDHs M2+:M3+ 2:1 with Mg:(Fe,Al), Mg:Fe, Zn:(Fe,Al), and Zn:Fe is investigated by means of quantum mechanical calculations based on the density functional theory (DFT). Several relative proportions of Fe are studied. The cation ordering of these LDHs has been explored, finding useful insights for experimental synthetic paths of these minerals. The a and b cell parameters increase with the iron concentration. Some diffraction lines at high angle decrease in angle and increase in intensity with the increasing iron concentration. All of them agree with the experimental results. The iron substitutions tend to aggregate.
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Pina, C. M., Pimentel, C., & Crespo, A. (2022). The Dolomite Problem: A Matter of Time. Acs Earth And Space Chemistry, 6(6), 1468–1471.
Résumé: Why is the mineral dolomite, CaMg(CO3)(2), abundant in ancient sedimentary rocks but scarce in modern rock-forming environments? What are the natural processes that lead to the characteristic Mg-Ca order in the dolomite structure? These important geological questions have captivated the interest of geoscientists for over a century, but the answers still remain elusive. Only recently, by the development of experimental work and the generation of large geochemical data sets, we began to suspect that both the formation and Mg-Ca ordering of dolomite could be the result of progressive dissolution-(re)crystallization reactions extended over large geological periods of time. Here, we present an initial estimate of dolomite cation-ordering times derived from previously reported data of Phanerozoic dolomites. This result provides new insight into the process of dolomite formation in nature, and it clearly suggests that can be possible to precisely determine the kinetics of the Mg- Ca ordering of natural dolomites.
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Pina-Valdes, J., Socquet, A., Beauval, C., Doin, M. - P., D'Agostino, N., & Shen, Z. - K. (2022). 3D GNSS Velocity Field Sheds Light on the Deformation Mechanisms in Europe: Effects of the Vertical Crustal Motion on the Distribution of Seismicity. Journal Of Geophysical Research-Solid Earth, 127(6).
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Pinel, V., Furst, S., Maccaferri, F., & Smittarello, D. (2022). Buoyancy Versus Local Stress Field Control on the Velocity of Magma Propagation: Insight From Analog and Numerical Modelling. Frontiers In Earth Science, 10.
Résumé: Magmatic dykes interact with heterogeneous crustal stress. As a result, their propagation towards the surface can be tortuous and their propagation velocity may vary. While the deflection of dykes in response to the local stress field has been addressed by several studies, less has been done about the effect on their propagation velocity. Understanding under which conditions an intrusion may accelerate or decelerate due to crustal stress heterogeneities has obvious important implications in terms of forecasting the timing of the onset of the eruption. Here we analyse the velocity of fluid-filled crack propagation in a gelatin block characterized by a heterogenous stress field considering the case study of a load applied at the surface. We find that a crack deflected towards the load and its underlying compressive stress field is decelerated. By comparing experimental results with numerical solutions, we evidence the potential complementary role played by stress field variations and changes in trajectory orientation, controling the buoyancy, on the velocity of magma propagation. We also show that the energy release estimated along the crack path by simplified numerical models appears to be a good proxy for the velocity. We conclude that numerical models allowing for magma path estimations could also be used to infer magma velocity variations. In addition, 1D numerical models solving for the fluid flow along a prescribed path, provide velocity variation as a function of the surrounding stress field and the magma driving pressure.
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Piraquive, A., Kammer, A., Bernet, M., Cramer, T., von Quadt, A., & Gomez, C. (2022). Neoproterozoic to Jurassic tectono-metamorphic events in the Sierra Nevada de Santa Marta Massif, Colombia: insights from zircon U-Pb geochronology and trace element geochemistry. International Geology Review, 64(14), 1933–1965.
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Pladys, A., Brossier, R., Kamath, N., & Metivier, L. (2022). Robust full-waveform inversion with graph-space optimal transport: Application to 3D ocean-bottom cable Valhall data. Geophysics, 87(3), R261–R280.
Résumé: Improving full-waveform inversion robustness to cycle -skipping has been the subject of a large number of studies. From the several families of approaches developed, one of the most documented consists in modifying the least-squares distance misfit function. From all the propositions made to improve and replace the least-squares distance, only a few of them have been applied to field data. One of the methods proposed recently, the graph space optimal transport distance, presents appealing properties for field data applications. We compare it with the least-squares distance in an analysis performed on the three-dimensional ocean bottom cable data from the Valhall field. We first perform this comparison starting the inversion from the reflection traveltime tomography model used in previous studies. We then perform a second comparison from a crude, linearly varying indepth one-dimensional velocity model. Starting from this model, least-squares-based full-waveform inversion fails to provide a meaningful estimate of the pressure-wave velocity model due to cycle skipping. We illustrate how the graph-space optimal transport-based full-waveform inversion mitigates this issue. A meaningful estimate of the pressure-wave velocity model is obtained in the zone sampled by both diving and reflected waves, down to almost two kilometers depth.
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Plunian, F., & Alboussiere, T. (2022). Fast and furious dynamo action in the anisotropic dynamo. Journal Of Fluid Mechanics, 941.
Résumé: In the limit of large magnetic Reynolds numbers, it is shown that a smooth differential rotation can lead to fast dynamo action, provided that the electrical conductivity or magnetic permeability is anisotropic. If the shear is infinite, for example between two rotating solid bodies, the anisotropic dynamo becomes furious, meaning that the magnetic growth rate increases toward infinity with an increasing magnetic Reynolds number.
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Pokrovski, G. S., Sanchez-Valle, C., Guillot, S., Borisova, A. Y., Munoz, M., Auzende, A. - L., et al. (2022). Redox dynamics of subduction revealed by arsenic in serpentinite. Geochemical Perspectives Letters, 22, 36–41.
Résumé: Redox dynamics of subduction processes remain poorly constrained owing to the lack of direct geochemical tracers. We studied, using X-ray absorption spectroscopy, the chemical and redox state of arsenic in the Tso Morari serpentinites that are witnesses of the Himalayan subduction. Our measurements reveal remarkably contrasting redox speciation, from arsenide (As-III) to arsenite (As-III) and arsenate (As-V). Combined with physical-chemical constraints, these data enable reconstruction of the 'redox travel' of arsenic in the subduction process. Upon early serpentinisation of mantle peridotite, arsenic was scavenged from the fluid and dragged down as insoluble nickel arsenide. Partial deserpentinisation close to the peak metamorphism (550-650 degrees C) resulted in oxidative dissolution of arsenide to aqueous As-III and As-V and their non-specific intake by antigorite. The As-V/As-III ratios (similar to 0.1-10) analysed in the mineral are similar to 10(4) times higher on average than predicted assuming bulk system thermodynamic equilibrium. These findings reflect a transient out-of-equilibrium release of highly oxidised fluids, with f(O2) reaching similar to 10 log units above the fayalite-magnetite-quartz buffer (FMQ+10). Arsenic in serpentinite is thus a sensitive record of subduction redox dynamics inaccessible when using traditional equilibrium approaches applied to bulk fluid-mineral systems.
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Poli, P., & Shapiro, N. M. (2022). Rapid Characterization of Large Volcanic Eruptions: Measuring the Impulse of the Hunga Tonga Ha'apai Explosion From Teleseismic Waves. Geophysical Research Letters, 49(8).
Résumé: Most of the largest volcanic activity in the world occurs in remote places such as deep oceans or poorly monitored oceanic island arcs. Thus, our capacity of monitoring volcanoes is limited to remote sensing and global geophysical observations. However, the rapid estimation of volcanic eruption parameters is needed for scientific understanding of the eruptive process and rapid hazard estimation. We present a method to rapidly identify large volcanic explosions, based on analysis of seismic data. With this methodology, we promptly detect the 15 January 2022 Hunga Tonga Ha'apai eruption. We then analyze the seismic waves generated by the volcanic explosion and estimate its important first-order parameters. We further relate the parameters with the volcanic explosivity index (VEI). Our estimate of VEI similar to 6 indicates that how the Hunga Tonga eruption is among the largest volcanic activity ever recorded with modern geophysical instrumentation and can provide new insights into the physics of large eruptions.
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Poli, P., Cabrera, L., Flores, M. C., Baez, J. C., Ammirati, J. B., Vasquez, J., et al. (2022). Volcanic Origin of a Long-Lived Swarm in the Central Bransfield Basin, Antarctica. Geophysical Research Letters, 49(1).
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Poulain, A., Fernandez-Martinez, A., Greneche, J. - M., Prieur, D., Scheinost, A. C., Menguy, N., et al. (2022). Selenium Nanowire Formation by Reacting Selenate with Magnetite. Environmental Science & Technology, 56(20), 14817–14827.
Résumé: lived radioisotope, is an important parameter in the safety assessment of radioactive nuclear waste disposal systems. Nonradioactive selenium is also an important contaminant of drainage waters from black shale mountains and coal mines. Highly mobile and soluble in its high oxidation states, selenate (Se(VI)O42-) and selenite (Se(IV)O32-) oxyanions can interact with magnetite, a mineral present in anoxic natural environments and in steel corrosion products, thereby being reduced and consequently immobilized by forming low-solubility solids. Here, we investigated the sorption and reduction capacity of synthetic nanomagnetite toward Se(VI) at neutral and acidic pH, under reducing, oxygen-free conditions. The additional presence of Fe(II)aq, released during magnetite dissolution at pH 5, has an effect on the reduction kinetics. X-ray absorption spectroscopy analyses revealed that, at pH 5, trigonal gray Se(0) formed and that sorbed Se(IV) complexes remained on the nanoparticle surface during longer reaction times. The Se(0) nanowires grew during the reaction, which points to a complex transport mechanism of reduced species or to active reduction sites at the tip of the Se(0) nanowires. The concomitant uptake of aqueous Fe(II) and Se(VI) ions is interpreted as a consequence of small pH oscillations that result from the Se(VI) reduction, leading to a re-adsorption of aqueous Fe(II) onto the magnetite, renewing its reducing capacity. This effect is not observed at pH 7, where we observed only the formation of Se(0) with slow kinetics due to the formation of an oxidized maghemite layer. This indicates that the presence of aqueous Fe(II) may be an important factor to be considered when examining the environmental reactivity of magnetite.
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Pousse-Beltran, L., Benedetti, L., Fleury, J., Boncio, P., Guillou, V., Pace, B., et al. (2022). Cl-36 exposure dating of glacial features to constrain the slip rate along the Mt. Vettore Fault (Central Apennines, Italy). Geomorphology, 412.
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Pradas del Real, A. E., Mitrano, D. M., Castillo-Michel, H., Wazne, M., Reyes-Herrera, J., Bortel, E., et al. (2022). Assessing implications of nanoplastics exposure to plants with advanced nanometrology techniques. Journal Of Hazardous Materials, 430.
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Provost, F., Michea, D., Malet, J. - P., Boissier, E., Pointal, E., Stumpf, A., et al. (2022). Terrain deformation measurements from optical satellite imagery: The MPIC-OPT processing services for geohazards monitoring. Remote Sensing Of Environment, 274.
Résumé: Measuring terrain deformation over several spatial and temporal scales is relevant for many applications in Earth Sciences (i.e. active faults, volcanoes, landslides or glaciers understanding). The growing volume of freely available data represents nowadays a challenge in terms of storage capacity and computing resources which, together with the complexity of the processing (code parameterization, combination of the image sequences, coregistration of the images) may prevent the exploitation of long time series. We propose here a new version of the Multiple-Pairwise Image Correlation toolbox for processing OPTical images (MPIC-OPT). The toolbox proposes an end-to-end solution to compute the horizontal sub-pixel ground deformation time series from large Sentinel-2 datasets. In addition to time series inversion, several corrections and filtering options are integrated to reduce the noise and improve the accuracy and precision of the measurements. In particular, an automatic jitter correction based on wavelet filtering is proposed. Moreover, the MPIC-OPT service is deployed on the Tier 1.5 HighPerformance Computing cluster (e.g. Datacentre/EOST-A2S) of the University of Strasbourg and is accessible on-line through the ESA Geohazards Exploitation Platform (GEP) and the ForM@Ter Solid Earth computing infrastructure with a user-friendly environment to query the satellite data catalogues, parameterize the processing and visualize the outputs. We test the performances of MPIC-OPT on several use cases: the measurement of the co-seismic ground deformation of the 2019 Ridgecrest earthquake sequence (USA), of the rapid motion of the Slumgullion landslide (USA) and of the glaciers of the Mont-Blanc massif (France/Italy). We show that the results of MPIC-OPT are in agreement with in-situ data. The jitter correction significantly improves the precision (RMSEjitter=0.3m vs. RMSEnojitter=0.5m) and the accuracy (RMSEjitter=0.3m vs. RMSEnojitter=1.3m) of the measurement of the co-seismic displacement of the Rigdecrest seismic deformation. We show that the precision and accuracy of the terrain deformation estimation depend mainly on the correlation threshold and the temporal matching range parameters and we quantify and discuss their impacts. This work opens new perspectives to monitor automatically surface displacements/velocities of natural hazards over large scales and large periods of time.
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Quesnel, B., Truche, L., Cathelineau, M., Boiron, M. - C., Lempart-Drozd, M., Rigaudier, T., et al. (2022). Significance of H-2 and CO release during thermal treatment of natural phyllosilicate-rich rocks. Chemical Geology, 588.
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Ramothe, V., Charlet, L., Gilbert, B., Simonnin, P., Sassi, M., & Rosso, K. M. (2022). Ab initio modeling of H2S dissociative chemisorption on Ag(100). Physical Chemistry Chemical Physics, 24(31), 18751–18763.
Résumé: Natural sulfidation of silver nanomaterials can passivate the surface, while preserving desirable optical and electrical properties, which is beneficial for limiting Ag+ release and cytotoxicity. But little is known at the atomic scale about silver sulfidation mechanisms, particularly on different crystallographic terminations. Using density functional theory (DFT) calculations, we examined the process of H2S sorption and reaction on Ag(100) surfaces relevant to Ag nanowires (AgNWs). DFT energy minimizations predict a strong dissociative chemisorption of H2S on the surface yielding co-adsorbed sulfide and hydrogen atoms in specific surface sites. However, nudged elastic band (NEB) calculations suggest relatively large activation energies for both the first and second dissociation steps, due in part to overcoming the energy to cleave the S-H bond and attendant site migration from an on-top Ag site position to a hollow site position of the bound S atom. The large barriers associated with the dissociative chemisorption reaction for gas-phase H2S points to the importance of including thermochemical contributions and the influence of other components in more complex environmental media such as air or water to help complete the mechanistic picture of silver sulfidation and passivation for realistic systems.
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Rashidi, A., Dutykh, D., Keshavarz, N., & Audin, L. (2022). Regional tsunami hazard from splay faults in the Gulf of Oman. Ocean Engineering, 243.
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Regard, V., Premaillon, M., Dewez, T. J. B., Carretier, S., Jeandel, C., Godderis, Y., et al. (2022). Rock coast erosion: An overlooked source of sediments to the ocean. Europe as an example. Earth And Planetary Science Letters, 579.
Résumé: Current assessments of the continent-to-ocean sediment budget assume that river discharge provides 11-21 Gt/a (72-89%) of the global sediment flux to the ocean. The remaining 11-28% supposedly comes mainly from glacially-derived sediments and airborne dust. Until recently, the contribution from rock coasts was estimated to represent 0.4 Gt/a, representing only 2-4% of the total flux. For the first time, and using the most complete global compilation of sea cliff recession rates in Europe, this study evaluates the rock coast contribution to sediment flux. We show that this sediment flux has been largely underestimated, and reveal that cliff derived sediment supply is only three times less than the solid discharge of rivers (111 & PLUSMN; 65 vs. 290 Mt/a) for Europe. This new estimate of the rock coast erosion should be included in future studies on the evolution of the surficial Earth system.(C) 2021 Elsevier B.V. All rights reserved.
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Regnault, M., Marrocchi, Y., Piralla, M., Villeneuve, J., Batanova, V., Schnuriger, N., et al. (2022). Oxygen isotope systematics of chondrules in Rumuruti chondrites: Formation conditions and genetic link with ordinary chondrites. Meteoritics & Planetary Science, 57(1), 122–135.
Résumé: Rumurutiites (R chondrites) are rare, highly oxidized chondrites belonging to the noncarbonaceous superclan and characterized by low chondrule abundances. Although textural and chemical features of Rumurutiite chondrules resemble those of ordinary chondrites (OCs), their formation conditions and potential genetic link remain debated. Here, we report high-resolution elemental X-ray mapping analyses and in situ O isotopic measurements of olivine grains from five chondrules and eight isolated olivine grains (IOGs) in the NWA 12482 R3 chondrite. The chondrules show chemical zonings similar to their counterparts in ordinary and carbonaceous chondrites (CCs), implying that gas-melt interaction processes between chondrule precursors and SiO- and Mg-rich gas were operative throughout the circumsolar disk. Our isotopic data show that R chondrules are isotopically similar to ordinary chondrules, although differences in their abundances of relict olivine grains and chondrule textural characteristics suggest different formation environments, with R chondrules being formed from O-16-poorer precursors. As with chondrules in OCs, the O isotopic characteristics of R chondrules and IOGs suggest limited transport between CC and noncarbonaceous reservoirs.
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Reigl, S., Van Driessche, A. E. S., Mehringer, J., Koltzenburg, S., Kunz, W., & Kellermeier, M. (2022). Revisiting the roles of salinity, temperature and water activity in phase selection during calcium sulfate precipitation. Crystengcomm, 24(8), 1529–1536.
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Rolland, Y., Bilau, A., Cardinal, T., Nouibat, A., Bienveignant, D., Boschetti, L., et al. (2022). Bridging the Gap between Long-Term Orogenic Evolution (> 10 Ma Scale) and Geomorphological Processes That Shape the Western Alps: Insights from Combined Dating Approaches. Geosciences, 12(11).
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Rosa, A. D., Dewaele, A., Garbarino, G., Svitlyk, V., Morard, G., De Angelis, F., et al. (2022). Martensitic fcc-hcp transformation pathway in solid krypton and xenon and its effect on their equations of state. Physical Review B, 105(14).
Résumé: The martensitic transformation is a fundamental physical phenomenon at the origin of important industrial applications. However, the underlying microscopic mechanism, which is of critical importance to explain the outstanding mechanical properties of martensitic materials, is still not fully understood. This is because for most martensitic materials the transformation is a fast process that makes in situ studies extremely challenging. Noble solids krypton and xenon undergo a progressive pressure-induced face-centered cubic (fcc) to hexagonal close-packed (hcp) martensitic transition with a very wide coexistence domain. Here, we took advantage of this unique feature to study the detailed transformation progress at the atomic level by employing in situ x-ray diffraction and absorption spectroscopy. We evidenced a four-stage pathway and suggest that the lattice mismatch between the fcc and hcp forms plays a key role in the generation of strain. We also determined precisely the effect of the transformation on the compression behavior of these materials.
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Sager, K., Tsai, V. C., Sheng, Y., Brenguier, F., Boue, P., Mordret, A., et al. (2022). Modelling P waves in seismic noise correlations: advancing fault monitoring using train traffic sources. Geophysical Journal International, 228(3), 1556–1567.
Résumé: The theory of Green's function retrieval essentially requires homogeneously distributed noise sources. Even though these conditions are not fulfilled in nature, low-frequency (<1 Hz) surface waves generated by ocean-crust interactions have been used successfully to image the crust with unprecedented spatial resolution. In contrast to low-frequency surface waves, high-frequency (>1 Hz) body waves have a sharper, more localized sensitivity to velocity contrasts and temporal changes at depth. In general, their retrieval using seismic interferometry is challenging, and recent studies focus on powerful, localized noise sources. They have proven to be a promising alternative but break the assumptions of Green's function retrieval. In this study, we present an approach to model correlations between P waves for these scenarios and analyse their sensitivity to 3-D Earth structure. We perform a series of numerical experiments to advance our understanding of these signals and prepare for an application to fault monitoring. In the considered cases, the character of the signals strongly diverges from Green's function retrieval, and the sensitivity to structure has significant contributions in the source direction. An accurate description of the underlying physics allows us to reproduce observations made in the context of monitoring the San Jacinto Fault in California using train-generated seismic waves. This approach provides new perspectives for detecting and localizing temporal velocity changes previously unnoticed by commonly exploited surface-wave reconstructions.
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Sarret, G., Schreck, E., Findling, N., Daval, D., Viers, J., Delplace, G., et al. (2022). Chemical status of zinc in plant phytoliths: Impact of burning and (paleo) environmental implications. Science Of The Total Environment, 852.
Résumé: Phytoliths are microscopic structures made of amorphous opal (opal-A), an amorphous hydrated silica, dispersed within plant tissues and persisting after the decay of the plant. Silicon is known to alleviate metal toxicity in plants, but the role of phytoliths in metal sequestration and detoxification is unclear. Dry ashing, the most common protocol for phytolith extraction, was previously shown to lead to sequestration of metals by the phytoliths; however, the mech-anisms of this process remained elusive. The purpose of this study was to evaluate whether the association between metals and phytoliths results from dry ashing or pre-exists in plant tissues. Thus, we compared phytoliths extracted by dry ashing at 700 degrees C and plant leaves before and after dry ashing. A combination of ICP-MS, XRD, SEM-EDX and Zn-K-edge EXAFS spectroscopy was used to assess elemental concentrations, morphology and crystallography of silica, and chemical status of Zn. Results demonstrated a phase transition from amorphous opal (opal-A) to opal-CT and alpha-cristobalite, and the sequestration of metal in phytoliths during dry ashing. For Zn, Mn and Pb, a linear relation-ship was found between the concentration in phytoliths and in leaves. In the phytoliths, Zn was sequestered in silica in tetrahedral configuration. We hypothesize that this association results form a solid-state reaction during ashing, in-volving a redistribution of Zn from the organic material to the silica, possibly promoted by the release of structural water from amorphous opal throughout the heating procedure. This study improves our understanding of the impact of high temperature treatments on plant biomass and phytoliths. It suggests that Zn toxicity alleviation in plants by silicon does not rely on its sequestration by phytoliths. In natural settings, wild fire events and biomass burning may lead to metal sequestration in low-soluble form, which should be considered in modeling of biogeochemical cycles and in paleoenvironmental studies.
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Schnuriger, N., Cartier, C., Villeneuve, J., Batanova, V., Regnault, M., & Marrocchi, Y. (2022). Spinel In Cv Chondrules: Investigating Percursor Legacy And Chondrule Thermal Histories. Meteoritics & Planetary Science, 57.
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Schnuriger, N., Cartier, C., Villeneuve, J., Batanova, V., Regnault, M., & Marrocchi, Y. (2022). Spinel in CV chondrules: Investigating precursor legacy and chondrule thermal histories. Meteoritics & Planetary Science, 57(5), 1018–1037.
Résumé: In carbonaceous chondrites, Mg-spinel (MgAl2O4) grains are ubiquitous in refractory inclusions but rarely reported in chondrules, where they may correspond to minerals either (i) inherited from chondrule precursors or (ii) crystallized from chondrule melts. Here, we report high-current quantitative electron microprobe measurements and secondary ion mass spectrometry oxygen isotopic analyses of Mg-spinel-bearing chondrules in the CV3 carbonaceous chondrites Northwest Africa 10235 and Allende. Compared to spinels in refractory inclusions, chondrule spinels are characterized by higher Cr contents and O-16-poorer oxygen isotopic signatures (Delta O-17 (math) delta O-17-0.52 x delta O-18, from -2 to -6 parts per thousand). Because the similar Delta O-17 values of chondrule olivine and spinel crystals imply their comagmatic origin, we applied a geothermometer based on the Al-Cr distribution between these minerals to determine their crystallization temperatures. The calculated temperatures range from 1200 to 1640 degrees C (mean = 1470 degrees C), most being lower than the estimated liquidus temperature of porphyritic chondrules (similar to 1600 degrees C). Our results suggest that chondrules experienced relatively slow cooling rates (slower than a few hundreds of degrees C h(-1)), which is in good agreement with models of chondrule formation invoking nonlinear or two-stage cooling rates.
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Serra, E., Magrani, F., Valla, P. G., Gribenski, N., Carcaillet, J., & Egholm, D. L. (2022). Lateglacial paleoglacier and paleoclimate reconstructions in the north- western Italian Alps. Quaternary Science Reviews, 298.
Résumé: Lateglacial (19.0-11.7 ka ago) paleo-temperature records in the Western European Alps document several short-term cooling episodes within the general post-Last Glacial Maximum warming trend, in phase with North Hemisphere climatic oscillations. Alpine paleo-precipitation reconstructions are instead rare, and further constraints are needed in order to assess whether Lateglacial cold periods were associated with a modified atmospheric circulation pattern over the European Alps. The Alpine paleo-glacial record offers a quantitative framework to investigate Lateglacial paleoclimatic conditions and glacier sensitivity in response to both temperature and precipitation changes. Through the combination of 10Be surface-exposure dating of glacial landforms and deposits constraining ice front and surface, together with numerical glacier simulations (iSOSIA), our study aims to reconstruct in space and time the main Lateglacial ice stages and associated paleo-climatic conditions in three tributary valleys (Valpelline, Valsavarenche and Val di Cogne) located within the Dora Baltea catchment (north-western Italian Alps). Our dating-modelling approach reveals in all the three investigated sectors two distinct paleoglacier stages at ca. 13 and 11 ka, documenting respectively the ice configurations at the transition between the Oldest Dryas cold period and the Bolling-Allerod interstadial, and between the Younger Dryas cold period and the early Holocene warming. Numerical ice-simulation outcomes suggest a similar-to-today pre-cipitation pattern during the two ice stages, with either same absolute or homogeneously decreased precipitation values over the Dora Baltea catchment, although a unique quantitative solution of paleo-precipitation magnitudes could not be constrained from our dataset. Using present-day precipitation pattern and magnitude, our results provide paleo-temperature offsets from present-day between-3.3 and-3.8 degrees C for the older glacial stage, and-2.7 to-3.2 degrees C for the younger glacial stage, coinciding with the upper range of paleo-temperature reconstructions from other paleoclimatic proxies. Finally, Alpine glaciers' sensitivity to climate fluctuations differ significantly between the investigated catchments, with a much higher glacier sensitivity to changes in the Equilibrium Line Altitude in the northern (Valpelline) compared to the southern (Valsavarenche and Val di Cogne) tributaries, reflecting different topographic and/or climatic conditions between the three valleys.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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Serra, E., Valla, P. G., Delunel, R., Gribenski, N., Christl, M., & Akcar, N. (2022). Spatio-temporal variability and controlling factors for postglacial denudation rates in the Dora Baltea catchment (western Italian Alps). Earth Surface Dynamics, 10(3), 493–512.
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Serra, E., Valla, P. G., Gribenski, N., Carcaillet, J., & Deline, P. (2022). Post-LGM glacial and geomorphic evolution of the Dora Baltea valley (western Italian Alps). Quaternary Science Reviews, 282.
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Serrano-Vincenti, S., Condom, T., Campozano, L., Escobar, L. A., Walpersdorf, A., Carchipulla-Morales, D., et al. (2022). Harmonic Analysis of the Relationship between GNSS Precipitable Water Vapor and Heavy Rainfall over the Northwest Equatorial Coast, Andes, and Amazon Regions. Atmosphere, 13(11).
Résumé: This study finds the relationship between increases in precipitable water vapor (PWV), and intense rainfall events in four different climatological regions of South America's equatorial northwest: the coast, Andes valley, high mountains, and Amazon. First, the PWV was derived from tropospheric zenith delay measured by Global Navigation Satellite System (GNSS) instrumentation located near meteorological stations within the regions of interest using hourly data from the year 2014. A harmonic analysis approach through continuous wavelet cross-spectrum and coherence, as well as discrete wavelets, was used to determine a measure of the lags found between PWV and specific heavy rain events and then compared with satellite IR images and meteorological anomalies. The link between PWV peaks and rainfall was the most evident on the coast, and less discernible in the other stations possibly due to local dynamic factors. The results showed a lag of 11 h between the preceding PWV increase and an intense rainfall event. This was apparent in all of the stations, except in Amazon where it was 6 h, with the highest precision at the coast and with the largest dispersion in the high mountains. The interpretation of this lag for each region is also discussed.
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Serripierri, A., Moreau, L., Boue, P., Weiss, J., & Roux, P. (2022). Recovering and monitoring the thickness, density, and elastic properties of sea ice from seismic noise recorded in Svalbard. Cryosphere, 16(6), 2527–2543.
Résumé: Due to global warming, the decline in the Arctic sea ice has been accelerating over the last 4 decades, with a rate that was not anticipated by climate models. To improve these models, there is the need to rely on comprehensive field data. Seismic methods are known for their potential to estimate sea-ice thickness and mechanical properties with very good accuracy. However, with the hostile environment and logistical difficulties imposed by the polar regions, seismic studies have remained rare. Due to the rapid technological and methodological progress of the last decade, there has been a recent reconsideration of such approaches. This paper introduces a methodological approach for passive monitoring of both sea-ice thickness and mechanical properties. To demonstrate this concept, we use data from a seismic experiment where an array of 247 geophones was deployed on sea ice in a fjord at Svalbard, between 1 and 24 March 2019. From the continuous recording of the ambient seismic field, the empirical Green function of the seismic waves guided in the ice layer was recovered via the so-called “noise correlation function”. Using specific array processing, the multi-modal dispersion curves of the ice layer were calculated from the noise correlation function, and then inverted for the thickness and elastic properties of the sea ice via Bayesian inference. The evolution of sea-ice properties was monitored for 24 d, and values are consistent with the literature, as well as with measurements made directly in the field.
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Shen, C., Brito, D., Diaz, J., Sanjuan, F., Bordes, C., & Garambois, S. (2022). Pulsed-laser source characterization in laboratory seismic experiments. Geomechanics And Geophysics For Geo-Energy And Geo-Resources, 8(1).
Résumé: The present study aimed to characterize the properties of a laser-generated seismic source for laboratory-scale geophysical experiments. This consisted of generating seismic waves in aluminum blocks and a carbonate core via pulsed-laser impacts and measuring the wave-field displacement via laser vibrometry. The experimental data were quantitatively compared to both theoretical predictions and 2D/3D numerical simulations using a finite element method. Two well-known and distinct physical mechanisms of seismic wave generation via pulsed-laser were identified and characterized accordingly: a thermoelastic regime for which the incident laser power was relatively weak, and an ablation regime at higher incident powers. The radiation patterns of the pulsed-laser seismic source in both regimes were experimentally measured and compared with that of a typical ultrasonic transducer. This study showed that this point-like, contact-free, reproducible, simple-to-use laser-generated seismic source was an attractive alternative to piezoelectric sources for laboratory seismic experiments, especially those concerning small scale, sub-meter measurements.
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Shible, H., Hollender, F., Bindi, D., Traversa, P., Oth, A., Edwards, B., et al. (2022). GITEC: A Generalized Inversion Technique Benchmark. Bulletin Of The Seismological Society Of America, 112(2), 850–877.
Résumé: Generalized inversion techniques (GITs) have become popular for determining seismological parameters (e.g., source, attenuation, and site response), particularly in low-to-moderate seismicity regions. Indeed, GITs can potentially provide reliable site-response estimates when a minimum number of recordings is available, as well as valuable information about source parameters and regional attenuation characteristics. Significant advances have been made on GITs in which different approaches and hypotheses were investigated, such as the application of “nonparametric” and “parametric” inversion schemes. In this context, several scientific questions have arisen that depend on the final scope of the GITs: What is the optimal inversion strategy for a given dataset configuration? What is the impact of the different choices, assumptions, and implementations on the reliability of the results? Is it possible to quantify the associated epistemic uncertainties? Here, we have considered and compared the different approaches of GITs to improve the understanding of each for use in different applications. A methodological benchmark that includes different GIT methods and dataset configurations is set up to fulfill the objective, using a simple synthetic dataset, a French regional sparse dataset, and an Italian national dense dataset. The benchmark is developed in two phases: (1) phase I: a free phase with no common constraints; and (2) phase II: a constrained phase with unified reference conditions. Despite unifying the reference conditions in the different inversions, the variability was not reduced. Discrepancies are observed between different terms of GITs. Site responses appear to be the most robust estimates, compared to source and attenuation terms. The way that stress drops of earthquakes and quality factors for crustal attenuation are parameterized appears to lead to significant variability between different approaches. Finally, uncertainties are addressed by quantification of the inter-method variability for the different terms and parameters.
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Shmeit, M., Giraud, F., Jaillard, E., Reboulet, S., Masrour, M., Spangenberg, J. E., et al. (2022). The Valanginian Weissert Event on the south Tethyan margin: A dynamic paleoceanographic evolution based on the study of calcareous nannofossils. Marine Micropaleontology, 175.
Résumé: Paleoceanographic conditions across the Valanginian Weissert oceanic anoxic event were reconstructed for the first time on the central Moroccan margin from a quantitative-based calcareous nannofossil study. Two onshore successions in the Essaouira-Agadir Basin and one offshore from DSDP Hole 416A were studied, providing a proximal-distal transect on the central Moroccan margin. The paleoceanographic conditions were reconstructed in an accurate chronostratigraphic framework. The sedimentary evolution of the Essaouira-Agadir Basin shows that sea-level variations controlled the paleogeographic context, clastic input, and nutrient availability. A thick photic zone and mesotrophic conditions favored the development of a diverse nannofossil community before the Weissert Event in the early Valanginian. In all studied successions, a collapse of the nannofossil community was recorded during the onset of the Weissert Event at the early-late Valanginian transition, and was caused by a major sea-level fall. The nannofossil community gradually recovered and reached its highest nannofossil production associated with high surface-water fertility during the Weissert Event in the late Valanginian. This eutrophication is coeval with the high and stable delta C-13(carb) values of the carbon-isotope positive shift. After the Weissert Event, surface-water fertility and nannofossil production decreased but remained higher than during the early Valanginian. Additionally, the nannoconid decline started in the early Valanginian and was linked to a low sea-level. Their recovery in the early late Valanginian occurred during conditions of high sea-level and of high surface-water fertility. The central Moroccan margin is integrated into a global paleoceanographic reconstruction.
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Singh, B., Malinowski, M., Gorszczyk, A., Malehmir, A., Buske, S., Sito, L., et al. (2022). 3D high-resolution seismic imaging of the iron oxide deposits in Ludvika (Sweden) using full-waveform inversion and reverse time migration. Solid Earth, 13(6), 1065–1085.
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Soergel, D., Pedersen, H. A., Bodin, T., Paul, A., & Stehly, L. (2022). 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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Son, S., Hyun, S. P., Charlet, L., & Kwon, K. D. (2022). Thermodynamic stability reversal of iron sulfides at the nanoscale: Insights into the iron sulfide formation in low-temperature aqueous solution. Geochimica Et Cosmochimica Acta, 338, 220–228.
Résumé: Understanding the formation of iron sulfides at low temperatures is essential for interpretation of geochemical signatures recorded in sedimentary sulfide minerals related to the evolution of the Earth's surface environment. Observed variations in the precipitation of nanoparticulate metastable phases prior to the formation of the stable-phase pyrite have been discussed from a kinetic perspective only. Here, using the ab-initio thermodynamic scheme to integrate surface thermodynamics with solid-aqueous equilibria, we demonstrate that stability relations among iron sulfides are dependent on particle size. The lower surface energies of metastable mackinawite and greigite than pyrite can drive reversals in relative thermodynamic stability at the nanoparticle scale and also lead to faster nucleation rates of the metastable phases, which are dependent on aqueous Eh-pH and Fe(II)/H2S conditions. This study emphasizes the role of surface energy in the formation pathways of iron sulfides and their particle-size dependent redox equilibria in anoxic aqueous solutions. (C) 2022 Elsevier Ltd. All rights reserved.
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Sonzogni, L., Ferlazzo, M. L., Granzotto, A., Fervers, B., Charlet, L., & Foray, N. (2022). DNA Double-Strand Breaks Induced in Human Cells by 6 Current Pesticides: Intercomparisons and Influence of the ATM Protein. Biomolecules, 12(2).
Résumé: A mechanistic model from radiobiology has emerged by pointing out that the radiation-induced nucleo-shuttling of the ATM protein (RIANS) initiates the recognition, the repair of DNA double-strand breaks (DSB), and the final response to genotoxic stress. More recently, we provided evidence in this journal that the RIANS model is also relevant for exposure to metal ions. To document the role of the ATM-dependent DSB repair and signaling after pesticide exposure, we applied six current pesticides of domestic and environmental interest (lindane, atrazine, glyphosate, permethrin, pentachlorophenol and thiabendazole) to human skin fibroblast and brain cells. Our findings suggest that each pesticide tested may induce DSB at a rate that depends on the pesticide concentration and the RIANS status of cells. At specific concentration ranges, the nucleo-shuttling of ATM can be delayed, which impairs DSB recognition and repair, and contributes to toxicity. Interestingly, the combination of copper sulfate and thiabendazole or glyphosate was found to have additive or supra-additive effects on DSB recognition and/or repair. A general mechanistic model of the biological response to metal and/or pesticide is proposed to define quantitative endpoints for toxicity.
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Stawski, T. M., & Van Driessche, A. E. S. (2022). Editorial for Special Issue “Formation of Sulfate Minerals in Natural and Industrial Environments”. Minerals, 12(3).
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Steinmann, R., Seydoux, L., Beauce, E., & Campillo, M. (2022). Hierarchical Exploration of Continuous Seismograms With Unsupervised Learning. Journal Of Geophysical Research-Solid Earth, 127(1).
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Steinmann, R., Seydoux, L., & Campillo, M. (2022). AI-Based Unmixing of Medium and Source Signatures From Seismograms: Ground Freezing Patterns. Geophysical Research Letters, 49(15).
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Suarez, R. J., Guillaume, B., Martinod, J., Ghiglione, M. C., Sue, C., & Kermarrec, J. - J. (2022). Role of convergence obliquity and inheritance on sliver tectonics: Insights from 3-D subduction experiments. Tectonophysics, 842.
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Svyazhin, A., Nalbandyan, V., Rovezzi, M., Chumakova, A., Detlefs, B., Guda, A. A., et al. (2022). Chemical Information in the L-3 X-ray Absorption Spectra of Molybdenum Compounds by High-Energy-Resolution Detection and Density Functional Theory. Inorganic Chemistry, 61(2), 869–881.
Résumé: X-ray spectroscopy using high-energy-resolution fluorescence detection (HERFD) has critically increased the information content in X-ray spectra. We extend this technique to the tender X-ray range and present a study at the L-3-edge of molybdenum. We show how information on the oxidation state, phase composition, and local environment in molybdenum-based compounds can be obtained by analyzing the HERFD L-3 X-ray absorption near-edge structure (XANES). We demonstrate that the chemical shift of the L-3-edge HERFD spectra follows a parabolic dependence on the oxidation state and show that a qualitative analysis of high-resolution spectra can help to estimate parameters such as distortion of a ligand environment and radial order of atoms around the absorber. In certain cases, the spectra allow disentangling the contributions from bond lengths and angles to the distortion of the ligand polyhedron. Comparison of the high-resolution spectra with theoretical simulations shows that the single-electron approximation is able to reproduce the spectral shape. The results of this work may be useful in every branch of physics, inorganic and organometallic chemistry, catalysis, materials science, biochemistry, and mineralogy where observed changes in performance or chemical properties of Mo-based compounds, accompanied by small changes in spectral shape, are to be related to the details of electronic structure and local atomic environment.
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Swann, Z., Camille, L., Pierre-Henri, B., Fabrizio, D., Laurence, A., Julien, C., et al. (2022). Cosmogenic 3He and 10Be denudation rates in the Central Andes: Comparison with a natural sediment trap over the last 18 ka. Earth And Planetary Science Letters, 599.
Résumé: It is of major importance for Earth surface sciences to reconstruct denudation rates in the most precise and accurate way. For this, it can be useful to test on the same setting methods based on different assumptions, such as those relying on geomorphological and geochemical observations. Here, we use an exceptionally suited setting in the Locumba catchment (southwestern Peruvian Andes) that offers the unique opportunity to compare denudation rates derived from in situ cosmogenic 3He and 10Be with a geomorphological sediment budget integrated over the last 18 ka. The sediment budget is estimated by determining the volume of sediment trapped in the Aricota lake that formed 18 ka ago after the occurrence of a giant rockslide dam. We reconstructed the topography of the Locumba valley before the dam emplacement and established that the captured sediment volume is 0.8 +/- 0.1 km3. Considering that the lake-water output is restricted to seepage through the dam and that overflow above the dam never occurred, this volume correctly represents the sediment flux integrated over the last 18 ka. Integrating this volume over the upstream catchment area (similar to 1500 km2), we derived a corresponding mean erosion rate of 30 +/- 9 mm.ka-1. Fluvial sediments feeding the Aricota lake were sampled to derive denudation rates from in-situ cosmogenic 10Be in the silicates and from in-situ cosmogenic 3He in the ferromagnesian minerals. Cosmogenic nuclide denudation rates from the main stream are 30 +/- 2, 33 +/- 2, 21 +/- 1 and 82 +/- 5 mm.ka-1 for the 10Be-quartz, the 10Be-feldspar, the 3He-amphibole and 3He-pyroxene, respectively. The consistency between the cosmogenic nuclide denudation rates derived from 10Be in the silicates and the erosion rate derived from our sediment budget shows that the 10Be accurately estimates of the sediment flux. Additionally, this work provides the first successful application of 10Be-feldspar nuclide-mineral pair to derive catchment-mean denudation rate and demonstrate that 10Be-feldspar can thus be a good alternative in catchments dominated by volcanic rocks with no quartz. The discrepancies observed between the denudation rates derived from the 3He-amphibole and 3He-pyroxene couples require further studies.(c) 2022 Elsevier B.V. All rights reserved.
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Tang, J. H., Brossier, R., & Metivier, L. (2022). Fully scalable solver for frequency-domain visco-elastic wave equations in 3D heterogeneous media: A controllability approach. Journal Of Computational Physics, 468.
Résumé: We develop a controllability strategy for the computation of frequency-domain solutions of the 3D visco-elastic wave equation, in the perspective of seismic imaging applications. We generalize the controllability results for such equations beyond the sound-soft scattering (obstacle) problem. We detail the conjugate gradient implementation and show how an inner elliptic problem needs to be solved to compute the Riesz representative of the gradient at each iteration. We select a spectral-element spatial discretization and a fourth -order Runge-Kutta time discretization. We implement the controllability method in the framework of the SEM46 full waveform modeling and inversion software, to inherit for its excellent scalability which relies on an efficient domain decomposition algorithm. We perform a series of numerical experiments to validate the approach and illustrate its scalability up to more than fifteen hundred cores. In this case, with an elapsed time of less than 50 minutes, we solve a problem on a cubic domain containing up to 160 wavelengths in each direction, involving more than 1.7 billion unknowns. (C) 2022 Elsevier Inc. All rights reserved.
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Thibaut, R., Compaire, N., Lesparre, N., Ramgraber, M., Laloy, E., & Hermans, T. (2022). Comparing Well and Geophysical Data for Temperature Monitoring Within a Bayesian Experimental Design Framework. Water Resources Research, 58(11).
Résumé: Temperature logs are an important tool in the geothermal industry. Temperature measurements from boreholes are used for exploration, system design, and monitoring. The number of observations, however, is not always sufficient to fully determine the temperature field or explore the entire parameter space of interest. Drilling in the best locations is still difficult and expensive. It is therefore critical to optimize the number and location of boreholes. Due to its higher spatial resolution and lower cost, four-dimensional (4D) temperature field monitoring via time-lapse Electrical Resistivity Tomography has been investigated as a potential alternative. We use Bayesian Evidential Learning (BEL), a Monte Carlo-based training approach, to optimize the design of a 4D temperature field monitoring experiment. We demonstrate how BEL can take into account various data source combinations (temperature logs combined with geophysical data) in the Bayesian optimal experimental design (BOED). To determine the optimal data source combination, we use the Root Mean Squared Error of the predicted target in the low dimensional latent space where BEL is solving the prediction problem. The parameter estimates are accurate enough to use in BOED. Furthermore, the method is not limited to monitoring temperature fields and can be applied to other similar experimental design problems. The method is computationally efficient and requires little training data. For the considered optimal design problem, a training set of only 200 samples and a test set of 50 samples is sufficient.
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Tisserand, D., Guedron, S., Viollier, E., Jezequel, D., Rigaud, S., Campillo, S., et al. (2022). Mercury, organic matter, iron, and sulfur co-cycling in a ferruginous meromictic lake. Applied Geochemistry, 146.
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Touma, R., Aubry, A., Ben-Zion, Y., & Campillo, M. (2022). Distribution of seismic scatterers in the San Jacinto Fault Zone, southeast of Anza, California, based on passive matrix imaging. Earth And Planetary Science Letters, 578.
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Triana, S. A., Dumberry, M., Cebron, D., Vidal, J., Trinh, A., Gerick, F., et al. (2022). Core Eigenmodes and their Impact on the Earth's Rotation. Surveys In Geophysics, 43(1), 107–148.
Résumé: Changes in the Earth's rotation are deeply connected to fluid dynamical processes in the outer core. This connection can be explored by studying the associated Earth eigenmodes with periods ranging from nearly diurnal to multi-decadal. It is essential to understand how the rotational and fluid core eigenmodes mutually interact, as well as their dependence on a host of diverse factors, such as magnetic effects, density stratification, fluid instabilities or turbulence. It is feasible to build detailed models including many of these features, and doing so will in turn allow us to extract more (indirect) information about the Earth's interior. In this article, we present a review of some of the current models, the numerical techniques, their advantages and limitations and the challenges on the road ahead.
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Valencia, K., De Moya, A., Morard, G., Allan, N. L., & Pinilla, C. (2022). Ab initio study of structural, elastic and thermodynamic properties of Fe3S at high pressure: Implications for planetary cores. American Mineralogist, 107(2), 248–256.
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van der Laat, L., Mora, M. M., Pacheco, J. F., Lesage, P., & Meneses, E. (2022). Seismicity during the recent activity (2009-2020) of Turrialba volcano, Costa Rica. Journal Of Volcanology And Geothermal Research, 431.
Résumé: Turrialba is a stratovolcano located at the easternmost part of the Costa Rican volcanic front. After remaining quiescent for more than a century, in 1996 it started to show signs of unrest, until a first phreatomagmatic explosion occurred on January, 2010. Since then, the activity evolved from phreatic to magmatic, in a series of distinct eruptive phases. In this paper, we investigate the seismic records that span the whole eruptive process (2010-present), in order to identify precursory signals and characterize the volcanic evolution. A long-term analysis was carried out based on the continuous records, as well as seismic catalogs (volcano-tectonic seis-micity, harmonic tremor, etc.). In addition, the gradual character of the evolution of this eruption allowed for the analysis of independent precursory stages. Thus, we inspected in detail the most important of those periods, particularly, prior to the first 2010 phreatomagmatic eruption, and prior to the 2016 transition to an open vent system. Temporary tremor amplitude decreases were found to precede most of the eruptive phases. In total, 9 pre-eruptive tremor abatement periods were identified spanning several days (5-44), which often concurred with a decrease in the SO2 flux. The analysis of the volcano-tectonic seismicity highlights the migration of magma from a deep (6-10 km) reservoir beneath the neighboring Irazu volcano towards Turrialba volcano, especially between the years 2015 and 2016. This activity peaked on December 2016 when a Mw 5.5 earthquake took place between both volcanoes. Harmonic tremor episodes thrived in the later phase when the system finally opened (2017-2018). In the short-term, compounded tonal seismic signals were identified as precursor events, such as long-period events followed by harmonic tremor or by a multichromatic coda similar to tornillo-type events. The co-occurrence of tremor amplitude decreases and tonal seismic signals is interpreted to be caused by a sealing of the hydrothermal system, which blocked the circulation of fluids and permitted the resonances in the inner cavities. This process leaded to pressure accumulation and the consequent eruptions. Thus, trough a series of cycles of sealing and rupture the system of conduits gradually opened. The seismic characterization of this eruption constitutes insightful knowledge useful for monitoring and risk assessment purposes.
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Van Driessche, A. E. S., Ling, W. L., Schoehn, G., & Sleutel, M. (2022). Nucleation of glucose isomerase protein crystals in a nonclassical disguise: The role of crystalline precursors. Proceedings Of The National Academy Of Sciences Of The United States Of America, 119(7).
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Van Maldeghem, F., Soens, B., van Ginneken, M., Maeda, R., Cordier, C., Suttle, M., et al. (2022). Chromites In Cosmic Spherules: A Unique Perspective On The Extraterrestrial Flux To Earth. Meteoritics & Planetary Science, 57.
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Van Stappen, J. F., McBeck, J. A., Cordonnier, B., Pijnenburg, R. P. J., Renard, F., Spiers, C. J., et al. (2022). 4D Synchrotron X-ray Imaging of Grain Scale Deformation Mechanisms in a Seismogenic Gas Reservoir Sandstone During Axial Compaction. Rock Mechanics And Rock Engineering, 55(8), 4697–4715.
Résumé: Understanding the grain-scale processes leading to reservoir compaction during hydrocarbons production is crucial for enabling physics-based predictions of induced surface subsidence and seismicity hazards. However, typical laboratory experiments only allow for pre- and post-experimental microstructural investigation of deformation mechanisms. Using high-resolution time-lapse X-ray micro-tomography imaging (4D μCT) during triaxial deformation, the controlling grain-scale processes can be visualized through time and space at realistic subsurface conditions. We deformed a sample of Slochteren sandstone, the reservoir rock from the seismogenic Groningen gas field in the Netherlands. The sample was deformed beyond its yield point (axial strain > 15%) in triaxial compression at reservoir P-T-stress conditions (100 degrees C, 10 MPa pore pressure, 40 MPa effective confining pressure). A total of 50 three-dimensional μCT scans were obtained during deformation, at a spatial resolution of 6.5 μm. Time lapse imaging plus digital volume correlation (DVC) enabled identification of the grain-scale deformation mechanisms operating throughout the experiment, for the first time, both at small, reservoir-relevant strains (< 1%), and in the approach to brittle failure at strains > 10%. During small-strain deformation, the sample showed compaction through grain rearrangement accommodated by inter-granular slip and normal displacements across grain boundaries, in particular, by closure of open grain boundaries or compaction of inter-granular clay films. At intermediate and large strains (> 4%), grain fracturing and pore collapse were observed, leading to sample-scale brittle failure. These observations provide key input for developing microphysical models describing compaction of the Groningen and other producing (gas) reservoirs.
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Vergoz, J., Hupe, P., Listowski, C., Le Pichon, A., Garces, M. A., Marchetti, E., et al. (2022). IMS observations of infrasound and acoustic-gravity waves produced by the January 2022 volcanic eruption of Hunga, Tonga: A global analysis. Earth And Planetary Science Letters, 591.
Résumé: The 15 January 2022 Hunga, Tonga, volcano's explosive eruption produced the most powerful blast recorded in the last century, with an estimated equivalent TNT yield of 100-200 megatons. The blast energy was propagated through the atmosphere as various wave types. The most prominent wave was a long-period (> 2000 s) surface-guided Lamb wave with energy comparable to that of the 1883 Krakatoa Lamb wave; both were clearly observed by pressure sensors (barometers) worldwide. Internal gravity, acoustic-gravity, and infrasound waves were captured in great detail by the entire infrasound component of the International Monitoring System (IMS). For instance, infrasound waves (< 300 s period) were seen to circumnavigate Earth up to eight times. Atmospheric waves captured by the IMS infrasound network and selected barometers near the source provide insight on Earth's impulse response at planetary scales. (C) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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Vezinet, A., Thomassot, E., Luo, Y., Pearson, D. G., Stern, R. A., & Sarkar, C. (2022). Zircon geochronology and Hf-O isotopes of the Nulliak supracrustal assemblage (Saglek Block-Canada): Constraints on deposition age and setting, metamorphic age and environments of zircon crystallization. Precambrian Research, 379.
Résumé: The Archean Saglek Block, North Atlantic craton, is one of the oldest crustal segments preserved on Earth. This area records two granulite facies metamorphic events: one in the late-Eoarchean at ca. 3.7 Ga and one in the Neoarchean, at ca. 2.75 Ga. Here, we report the results of combined U-Pb/Hf/O in-situ isotope analyses of detrital and metamorphic zircon domains from two meta-sedimentary samples, one psammitic, and one pelitic. Both samples are components of the oldest supra -crustal assemblage of the Saglek Block: the Eoarchean Nulliak supracrustal assemblage. The isotopic data presented in this study: (i) confirm deposition age of the Nulliak supracrustal assemblage before ca. 3.65 Ga, (ii) indicate local provenance of the detrital zircon, (iii) suggest deposition of the sedimentary protoliths in a convergent setting, such as an arc, (iv) crystallization of the oldest zircon during the early Eoarchean in a protolith derived from a depleted mantle component, (v) involvement of material that experienced prolonged low temperature alteration during the late Eoarchean granulite facies metamorphism and (vi) selective metamorphic overprinting during the Neoarchean granulite facies metamorphism. The new zircon U-Pb/Hf/O isotope data presented here in conjunction with previously published analyses suggest that a depleted mantle domain existed in the early Archean, as reflected in the positive epsilon Hf signature of zircon from the Saglek Block. Yet, such positive Hf isotope deviations are not the norm, but rather the exception in the preserved early Earth zircon record. In addition, mildly elevated zircon delta O-18 values, i.e. those >= 5.9 & PTSTHOUSND;, are as common in the early Archean as they are in the late-Archean zircon record, implying that crustal reworking was an active and efficient process all through the Archean. Hence, no significant variation in the nature of the reworking and broader geodynamic processes occurred during this period of time.
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Vezinet, A., Thomassot, E., Luo, Y., Sarkar, C., & Pearson, D. G. (2022). Diachronous Redistribution of Hf and Nd Isotopes at the Crystal Scale-Consequences for the Isotopic Evolution of a Poly-Metamorphic Crustal Terrane. Geosciences, 12(1).
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Vidal, J., & Cebron, D. (2022). Precession-driven flows in stress-free ellipsoids. Journal Of Fluid Mechanics, 954.
Résumé: Motivated by modelling rotating turbulence in planetary fluid layers, we investigate precession-driven flows in ellipsoids subject to stress-free boundary conditions (SF-BC). The SF-BC could indeed unlock numerical constraints associated with the no-slip boundary conditions (NS-BC), but are also relevant for some astrophysical applications. Although SF-BC have been employed in the pioneering work of Lorenzani & Tilgner (J. Fluid Mech., vol. 492, 2003, pp. 363-379), they have scarcely been used due to the discovery of some specific mathematical issues associated with angular momentum conservation. We revisit the problem using asymptotic analysis in the low-viscosity regime, which is validated with numerical simulations. First, we extend the reduced model of uniform-vorticity flows in ellipsoids to account for SF-BC. We show that the long-term evolution of angular momentum is affected by viscosity in triaxial geometries, but also in axisymmetric ellipsoids when the mean rotation axis of the fluid is not the symmetry axis. In a regime relevant to planets, we analytically obtain the primary forced flow in triaxial geometries, which exhibits a second inviscid resonance. Then, we investigate the bulk instabilities existing in precessing ellipsoids. We show that using SF-BC would be useful to explore the non-viscous instabilities (e.g. Kerswell, Geophys. Astrophys. Fluid Dyn., vol. 72, 1993, pp. 107-144), which are presumably relevant for planetary applications but are often hampered in experiments or simulations with NS-BC.
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Vidal, O., Le Boulzec, H., Andrieu, B., & Verzier, F. (2022). Modelling the Demand and Access of Mineral Resources in a Changing World. Sustainability, 14(1).
Résumé: Humanity is using mineral resources at an unprecedented level and demand will continue to grow over the next few decades before stabilizing by the end of the century, due to the economic development of populated countries and the energy and digital transitions. The demand for raw materials must be estimated with a bottom-up and regionalised approach and the supply capacity with approaches coupling long-term prices with energy and production costs controlled by the quality of the resource and the rate of technological improvement that depends on thermodynamic limits. Such modelling provides arguments in favour of two classically opposed visions of the future of mineral resources: an unaffordable increase in costs and prices following the depletion of high quality deposits or, on the contrary, a favourable compensation by technological improvements. Both views are true, but not at the same time. After a period of energy and production cost gains, we now appear to be entering a pivotal period of long-term production cost increases as we approach the minimum practical energy and thermodynamic limits for many metals.
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Vincent, C., Gilbert, A., Walpersdorf, A., Gimbert, F., Gagliardini, O., Jourdain, B., et al. (2022). Evidence of Seasonal Uplift in the Argentiere Glacier (Mont Blanc Area, France). Journal Of Geophysical Research-Earth Surface, 127(7).
Résumé: The hydromechanical processes by which basal water controls sliding at the glacier bed are poorly known, despite glacier basal motion being responsible for a large part of ice flux in temperate alpine glaciers. Previous studies suggest that sliding strongly relates to the quantity of water being stored at the ice-bedrock interface. However, this water storage is difficult to quantify accurately on the basis of surface-motion observations, given that uplift can also be affected by changes in vertical-strain rates and sliding velocity change. Here, we use a comprehensive data set of in situ measurements performed over 2 years on the Argentiere Glacier in the French Alps to investigate the relationships between horizontal and vertical velocities, basal sliding, subglacial runoff and bed separation. We observe strikingly large uplifts varying spatially between 0.20 and 0.90 m over the winter/spring seasons between January and June and with a consistent spatial pattern from 1 year to another. We show, based on observations and three dimensional ice-flow modeling, that these large uplifts cannot be explained solely by changes in strain rates or in sliding up an inclined bed. Our results reveal that more than 80% of the observed uplift is related to enhanced bed separation through cavitation, allowing us to estimate the volume occupied by water-filled subglacial cavities. Our interpretation of uplift being mainly caused by increased cavitation is also consistent with an associated increase in the observed surface horizontal velocity. These findings provide important observational constraints for testing subglacial hydrological models.
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Volkova, M. S., Shapiro, N. M., Melnik, O. E., Mikhailov, V. O., Plechov, P. Y., Timoshkina, E. P., et al. (2022). Subsidence of the lava flows emitted during the 2012-2013 eruption of Tolbachik (Kamchatka, Russia): Satellite data and thermal model. Journal Of Volcanology And Geothermal Research, 427.
Résumé: We estimated the subsidence rate of the lava flow formed during the 2012-2013 eruption of Tolbachik volcano from satellite radar interferometry with using Sentinel-1 satellite images between 2017 and 2019. The maximum subsidence values were 285 mm/yr in 2017, 249 mm/yr in 2018, and 261 mm/yr in 2019. The subsidence rate increases with the flow thickness. This trend is observed for most of locations except a small area in the vicinity of the active vent where the subsidence is anomalously high. We show that the main observed trend can be well explained by a thermal compaction with a 1D mathematical model that takes into account the latent heat of crystallization, temperature dependences of physical parameters (heat capacity, thermal conductivity, density), temperature dependence of crystal concentration in the melt volume, and the percentage of uncrystallized material (glass or melt), porosity and lava layer formation rate. The much faster subsidence rates observed close to the vent can be explained by contraction of buried lava tubes that is not accounted in the thermal model.
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Wang, K., Martinez, A. F., Simonelli, L., Made, B., Henocq, P., Ma, B., et al. (2022). Redox Interaction between Selenite and Mackinawite in Cement Pore Water. Environmental Science & Technology, 56(9), 5602–5610.
Résumé: In cement-rich radioactive waste repositories, mackinawite (FeS) forms at the steel corrosion interface within reinforced concrete and potentially retards the transport of redoxsensitive radionuclides (e.g., 79Se) in porous cement media. Redox interactions between selenite and mackinawite under hyperalkaline conditions remain unclear and require further investigations. Here, using comprehensive characterization on both aqueous and solid speciation, we successfully monitored the whole interaction process between selenite and mackinawite under hyperalkaline conditions. The results show similar chemical environments for SeO3 2- and S2-/Sn 2- at the mackinawite-water interface, verifying an immediate reduction. After 192 h of reaction, SeO3 2- was reduced to solid Se0 and SeS2 species, accompanied by the oxidation of S2-/Sn 2- to S2O3 2- and Fe(II) to Fe(III) in mackinawite. Aqueous speciation results showed that similar to 99% of aqueous selenium was present as Se4S nanoparticles due to the dissolution of Se from the solid. In parallel, similar to 62% of S2-/Sn 2- was released into the solution, with mackinawite transforming into magnetite, Fe(OH)3 and FeS2O3 + complexed to Cl- or OH- species, and magnetite subsequently dispersed in the solution. This study provides valuable data about the retardation mechanisms of redox-sensitive radionuclides by soluble iron sulfides, which is critical to advance our understanding of reactive concrete barriers used in nuclear waste disposal systems
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Wang, S., Nissen, E., Pousse-Beltran, L., Craig, T. J., Jiao, R., & Bergman, E. A. (2022). Structural controls on coseismic rupture revealed by the 2020 M-w 6.0 Jiashi earthquake (Kepingtag belt, SW Tian Shan, China). Geophysical Journal International, 230(3), 1895–1910.
Résumé: The Kepingtag (Kalpin) fold-and-thrust belt of the southern Chinese Tian Shan is characterized by active shortening and intense seismic activity. Geological cross-sections and seismic reflection profiles suggest thin-skinned, northward-dipping thrust sheets detached in an Upper Cambrian decollement. The 2020 January 19 M-w 6.0 Jiashi earthquake provides an opportunity to investigate how coseismic deformation is accommodated in this structural setting. Coseismic surface deformation resolved with Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) is centred on the back limb of the frontal Kepingtag anticline. Elastic dislocation modelling suggests that the causative fault is located at similar to 7 km depth and dips similar to 7 degrees northward, consistent with the inferred position of the decollement. Our calibrated relocation of the main shock hypocentre is consistent with eastward, unilateral rupture of this fault. The narrow slip pattern (length similar to 37 km but width only similar to 9 km) implies that there is a strong structural or lithological control on the rupture extent, with updip slip propagation possibly halted by an abrupt change in dip angle where the Kepingtag thrust is inferred to branch off the decollement. A depth discrepancy between main shock slip constrained by InSAR and teleseismic waveform modelling (similar to 7 km) and well-relocated aftershocks (similar to 10-20 km) may suggest that faults within sediments above the decollement exhibit velocity-strengthening friction.
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Wang, S., Replumaz, A., Chevalier, M. - L., & Li, H. (2022). Decoupling between upper crustal deformation of southern Tibet and underthrusting of Indian lithosphere. Terra Nova, 34(1), 62–71.
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Wang, S., Shen, X., Chevalier, M. - L., Replumaz, A., Zheng, Y., Li, H., et al. (2022). Illite K-Ar and (U-Th)/He low-temperature thermochronology reveal onset timing of Yadong-Gulu rift in southern Tibetan Plateau. Frontiers In Earth Science, 10.
Résumé: Determining the timing of E-W extension across the NS-trending rifts in southern Tibet is key to test the mechanical models of the latest evolution in the collision between India and Asia. We focus on the southern half of the largest of the seven main rifts, the Yadong-Gulu rift (YGR), which, despite being the focus of numerous studies thanks to its easy access, still lacks direct time constraints. Using illite K-Ar ages of fault gouge from the active Yadong normal fault of the YGR, we directly constrain its onset timing at 9 +/- 1 Ma. (U-Th)/He dating of the footwall leucogranite reveals a rapid exhumation of the southern YGR since -9 Ma, attesting to its onset activity. Such timing is similar to that estimated for the northern half of the YGR at 8 +/- 1 Ma, suggesting that the entire YGR formed at approximately the same time. Our synthesis of published initiation ages of the other main rifts in southern Tibet shows that they mostly fall between similar to 23 and 8 Ma, suggesting a clear spatial and temporal pattern of old initiation ages to the west and young to the east. In this case, the formation of rifts in southern Tibet is unlikely caused by slab tearing of the underthruting Indian plate or orogenic collapse. Our study supports that E-W extension in Tibetan Plateau is triggered by a combination of eastward propagation of the Karakorum-Jiali fault zone and divergent thrusting along the curved Himalayan arc.
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Wang, W., Savage, M. K., Yates, A., Zal, H. J., Webb, S., Boulton, C., et al. (2022). Temporal velocity variations in the northern Hikurangi margin and the relation to slow slip. Earth And Planetary Science Letters, 584.
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Wang, X., Li, X., Wang, L., Lanson, B., Zhu, M., Ying, C., et al. (2022). Effects of Mn or Al incorporation on the structure, composition, and As(III) adsorption of oxidized green rust. Chemical Geology, 611.
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Wilhelm, B., Amann, B., Corella, J. P., Rapuc, W., Giguet-Covex, C., Merz, B., et al. (2022). Reconstructing Paleoflood Occurrence and Magnitude from Lake Sediments. Quaternary, 5(1).
Résumé: Lake sediments are a valuable archive to document past flood occurrence and magnitude, and their evolution over centuries to millennia. This information has the potential to greatly improve current flood design and risk assessment approaches, which are hampered by the shortness and scarcity of gauge records. For this reason, paleoflood hydrology from lake sediments received fast-growing attention over the last decade. This allowed an extensive development of experience and methodologies and, thereby, the reconstruction of paleoflood series with increasingly higher accuracy. In this review, we provide up-to-date knowledge on flood sedimentary processes and systems, as well as on state-of-the-art methods for reconstructing and interpreting paleoflood records. We also discuss possible perspectives in the field of paleoflood hydrology from lake sediments by highlighting the remaining challenges. This review intends to guide the research interest in documenting past floods from lake sediments. In particular, we offer here guidance supported by the literature in how: to choose the most appropriate lake in a given region, to find the best suited sedimentary environments to take the cores, to identify flood deposits in the sedimentary sequence, to distinguish them from other instantaneous deposits, and finally, to rigorously interpret the flood chronicle thus produced.
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Xue, Q., Larose, E., Moreau, L., Thery, R., Abraham, O., & Henault, J. - M. (2022). Ultrasonic monitoring of stress and cracks of the 1/3 scale mock-up of nuclear reactor concrete containment structure. Structural Health Monitoring-An International Journal, 21(4), 1474–1482.
Résumé: To evaluate the stress level and damage of a reinforced concrete containment wall (similar to those used in nuclear power plants) and its reaction to pressure variations, we conducted successive ultrasonic experiments on the exterior surface of the containment wall in the gusset area for three consecutive years (2017, 2018 and 2019). During each experiment, the pressure inside the containment wall increased gradually from 0 MPa to 0.43 MPa and then decreased back to 0 MPa. From the analysis of the ultrasonic coda waves obtained in the multiple scattering regime (80-220 kHz), we performed Coda Wave Interferometry to calculate the apparent velocity changes in the structure (denoted by dV/V- a ) and Coda Wave Decorrelation (DC) measurements to produce 3D cartographies of stress and crack distribution. From three source-receiver pairs, located at the top, middle and bottom of the experimental region, we observe that coda waves dilate, shrink and remain almost unchanged, respectively. This corresponds to the decreasing, increasing and invariant pressure inside the concrete. The comparison of 3 years' results demonstrates that the variation of dV/V- a and DC under the same pressure test increases through the years, which indicates the progressive deterioration and ageing of the concrete. From a large collection of source-receiver pairs at different times, the spatial-temporal variations of dV/V- a and DC are then used to produce a map of the structural velocity and scattering changes, respectively. We observe a decreasing velocity on the top part and an increasing in the middle one, which is in line with the dV/V- a analysis. The reconstructed scattering changes (or structural changes) highlight the active region during the inflation-deflation procedure, corresponding to the opening and closing (and sometimes the development) of cracks. The larger magnitude in 2019 than in 2017 indicates the increasing damage in the concrete.
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Yakupoglu, N., Henry, P., Ucarkus, G., Eris, K. K., Demory, F., Crouzet, C., et al. (2022). Factors affecting thickness and frequency of turbidites triggered by earthquakes in Kumburgaz Basin, Sea of Marmara. Marine Geology, 452.
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Yates, A., Caudron, C., Lesage, P., Mordret, A., Lecocq, T., & Soubestre, J. (2022). 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.
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Yin, H., Lanson, B., Zhang, S., Liu, L., Peacock, C. L., Post, J. E., et al. (2022). Effect and fate of Ni during aging and thermal-induced phyllomanganate-to-tectomanganate transformation. Geochimica Et Cosmochimica Acta, 333, 200–215.
Résumé: Phyllomanganates are ubiquitous in a variety of environments and commonly enriched in transition metal elements, such as Ni. The effect of such foreign metal cations on phyllomanganate transformation is widely documented under aqueous conditions together with the induced modification of Ni geochemical behavior. A similar knowledge is lacking however on phyllomanganate transformation and on the induced fate of associated metal elements that may occur under dry conditions, that prevail in deserts and arid areas increasingly exposed to severe droughts or wildfires. The present study shows that crystallinity, morphology, Mn oxidation state, and Ni binding mechanisms are essentially unaffected when aging hexagonal birnessite (Mn oxidation state similar to 3.90 and Ni/Mn molar ratios of 0.00 and 0.13) in the dry state at room temperature for up to 8 years. In contrast, heating aged Ni-doped birnessite to 25-200 ? results in an increased proportion of edge-sharing Ni-Ni(Mn) pairs with increasing temperature induced by the migration of interlayer Ni to birnessite octahedral layers and/or by an increased sharing of coordination oxygens by interlayer Ni/Mn from adjacent layers. Further heating to 400 ? does not change this proportion, with birnessite layer structure being retained. Transformation of Ni-doped birnessite to cryptomelane is complete at 500 ?, while that of Ni-free birnessite is achieved at 400 ?, suggesting that Ni doping increases birnessite thermal stability. Birnessite-to-cryptomelane transformation comes with a strong increase of Mn oxidation state, whereas this parameter remains unchanged in heated birnessite samples. Ni incorporation in the cryptomelane framework, reduces its release during reductive acid dissolution by a factor of 396 +/- 15 compared to initial birnessite. These results shed light on mineral transformation affecting layered manganates under dry conditions and on the fate of associated transition metal elements. (C) 2022 Elsevier Ltd. All rights reserved.
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Yokoo, S., Hirose, K., Tagawa, S., Morard, G., & Ohishi, Y. (2022). Stratification in planetary cores by liquid immiscibility in Fe-S-H. Nature Communications, 13(1).
Résumé: Liquid-liquid immiscibility has been widely observed in iron alloy systems at ambient pressure and is important for the structure and dynamics in iron cores of rocky planets. While such previously known liquid immiscibility has been demonstrated to disappear at relatively low pressures, here we report immiscible S(+/- Si,O)-rich liquid and H(+/- C)-rich liquid above similar to 20 GPa, corresponding to conditions of the Martian core. Mars' cosmochemically estimated core composition is likely in the miscibility gap, and the separation of two immiscible liquids could have driven core convection and stable stratification, which explains the formation and termination of the Martian planetary magnetic field. In addition, we observed liquid immiscibility in Fe-S-H(+/- Si,O,C) at least to 118 GPa, suggesting that it can occur in the Earth's topmost outer core and form a low-velocity layer below the core-mantle boundary.
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Yong, P., Brossier, R., & Metivier, L. (2022). Parsimonious truncated Newton method for time-domain full-waveform inversion based on the Fourier-domain full-scattered-field approximation. Geophysics, 87(1), R123–R146.
Résumé: To exploit Hessian information in full-waveform inversion (FWI), the matrix-free truncated Newton method can be used. In such a method, Hessian-vector product computation is one of the major concerns due to the huge memory requirements and demanding computational cost. Using the adjoint-state method, the Hessian-vector product can be estimated by zero-lag crosscorrelation of the first-/second-order incident wavefields and the second-/first-order adjoint wavefields. Different from the implementation in frequency-domain FWI, Hessian-vector product construction in the time domain becomes much more challenging because it is not affordable to store all of the time-dependent wave-fields. The widely used wavefield recomputation strategy leads to computationally intensive tasks. We have developed an efficient alternative approach to computing the Hessian-vector product for time-domain FWI. In our method, discrete Fourier transform is applied to extract frequency-domain components of involved wavefields, which are used to compute wavefield crosscorrelation in the frequency domain. This makes it possible to avoid recon-structing the first-and second-order incident wavefields. In addi-tion, a full-scattered-field approximation is proposed to efficiently simplify the second-order incident and adjoint wavefield compu-tation, which enables us to refrain from repeatedly solving the first-order incident and adjoint equations for the second-order incident and adjoint wavefields (re)computation. With our method, the computational time can be reduced by 70% and 80% in viscous media for Gauss-Newton and full-Newton Hessian-vector product construction, respectively. The effectiveness of our method is also verified in the frame of a 2D multiparameter inversion, in which our method almost reaches the same iterative convergence of the conventional time-domain implementation.
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Zandanel, A., Hellmann, R., Truche, L., Roddatis, V., Mermoux, M., Choblet, G., et al. (2022). Geologically rapid aqueous mineral alteration at subfreezing temperatures in icy worlds. Nature Astronomy, 6(5), 554–559.
Résumé: The most active icy worlds such as Europa or Enceladus are predicted to host extensive aqueous alteration driven by water-rock interactions at elevated temperatures(1-3). On the other hand, it is assumed that such alteration is kinetically inhibited at the subzero temperatures of other icy worlds, such as the mid-sized moons of Saturn and Uranus or trans-Neptunian objects(1,4). Here we perform aqueous alteration experiments on a chondrite-analogue material (olivine) and find that chemical alteration processes are still efficient at temperatures as low as -20 degrees C, as the presence of an unfrozen water film still allows olivine to dissolve in partially frozen alkaline solutions. We infer that aqueous alteration may be enhanced by salts and ammonia present in icy worlds, and therefore remains a geologically rapid process even at subzero temperatures. Our results imply that the primary chondritic minerals in most icy bodies exceeding 400-500 km in diameter will be completely altered to hydrous secondary minerals early in their evolutionary histories.
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Zareeipolgardani, B., Piednoir, A., Joyard-Pitiot, B., Depres, G., Charlet, L., & Colombani, J. (2022). Multiscale investigation of the fate of silver during printed paper electronics recycling. Composite Interfaces, .
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Zhakiyeva, Z., Cuello, G. J., Fischer, H. E., Bowron, D. T., Dejoie, C., Magnin, V., et al. (2022). Structure of Water Adsorbed on Nanocrystalline Calcium Silicate Hydrate Determined from Neutron Scattering and Molecular Dynamics Simulations. Journal Of Physical Chemistry C, 126(30), 12820–12835.
Résumé: Calcium silicate hydrate (C-S-H) is a disordered, nanocrystalline material that acts as a primary binding phase in Portland cement. Thin films of water are present on the surfaces and in nanopores of C-S-H, impacting many of its chemical and mechanical properties, such as ion transport, creep, or thermal behavior. Despite decades of research, a full understanding of the structural details of adsorbed, confined, and bulk water in C-S-H remains elusive. In this work, we applied a multitechnique study involving molecular dynamics (MD) simulations validated by neutron diffraction with isotopic substitution (NDIS) and X-ray scattering methods to investigate the structure of water in C-S-H and C-A-S-H (an Al-bearing, low-CO2 C-S-H substitute). Direct comparison of NDIS data with the MD results reveals that the structure of confined and interfacial water differs significantly from the bulk water and exhibits a larger degree of mesoscale ordering for more hydrated C-S-H structures. This observation suggests an important role of water as a stabilizer of the atomistic-level structure of C-S-H.
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Zhang, S., Li, H., Wu, Z., Post, J. E., Lanson, B., Liu, Y., et al. (2022). Effects of cobalt doping on the reactivity of hausmannite for As(III) oxidation and As(V) adsorption. Journal of environmental sciences (China), 122, 217–226.
Résumé: Hausmannite is a common low valence Mn oxide mineral, with a distorted spinel structure, in surficial sediments. Although natural Mn oxides often contain various impurities of transitional metals (TMs), few studies have addressed the effect and related mechanism of TM doping on the reactivity of hausmannite with metal pollutants. Here, the reactivity of cobalt (Co) doped hausmannite with aqueous As(III) and As(V) was studied. Co doping decreased the point of zero charge of hausmannite and its adsorption capacity for As(V). Despite a reduction of the initial As(III) oxidation rate, Co-doped hausmannite could effectively oxidize As(III) to As(V), followed by the adsorption and fixation of a large amount of As(V) on the mineral surface. Arsenic K-edge EXAFS analysis of the samples after As(V) adsorption and As(III) oxidation revealed that only As(V) was adsorbed on the mineral surface, with an average As-Mn distance of 3.25-3.30 A, indicating the formation of bidentate binuclear complexes. These results provide new insights into the interaction mechanism between TMs and low valence Mn oxides and their effect on the geochemical behaviors of metal pollutants.
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