Séminaire ISTerre

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Finely Textured Planet: anisotropy of seismic properties as a means for understanding Earth’s interior.

lundi 13 novembre 2023 - 14h00

Vadim Levin - Department of Earth and Planetary Sciences, Rutgers University, USA
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Seismic waves are a preferred method for probing the interior of the Earth. Materials making up the Earth are expected to have directionally dependent properties (aka seismic anisotropy) that affect the speed and polarization of seismic waves going through them. Anisotropy can arise from a variety of mechanisms, from layering and cracks to systematic crystal lattice alignment. An ability to detect, describe and interpret anisotropic properties revolutionized global seismology in the last two decades, offering a way to observe directions of movement of large rock masses within Earth’s interior and to map past deformation episodes. In this presentation I will illustrate the use of seismic anisotropy observations in addressing two questions of various scale and geologic timing. I will use observations of birefringence in shear waves recorded in southern Costa Rica to support an argument for ongoing upper mantle flow between the Pacific and the Caribbean. I will also demonstrate how methods based on compressional-to-shear converted waves can image deformation zones preserved in the crust of the Appalachian Orogen since the time of Pangea formation, and what this can teach us about the continental collision process. Through these two case studies I will make a case that seismological methods can provide insight into history of past tectonic episodes and elucidate the workings of presently active tectonic regions.

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Equipe organisatrice : Ondes et structures

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/8172559109
ID : 817 255 9109