SAR and optical images correlation illuminates post-seismic landslide motion after the Mw 7.8 Gorkha earthquake (Nepal)

Autor: Lacroix, Pascal, Gavillon, Théo, Bouchant, Clément, Lavé, Jérôme, Mugnier, Jean-Louis, Dhungel, Samir, Vernier, Flavien, Mikalsen, Bjørg
Přispěvatelé: Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Tribhuvan University, Laboratoire d'Informatique, Systèmes, Traitement de l'Information et de la Connaissance (LISTIC), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Centre National D’études Spatiales (CNES)
Rok vydání: 2022
Předmět:
Zdroj: Scientific Reports
Scientific Reports, 2022, 12 (1), pp.6266. ⟨10.1038/s41598-022-10016-2⟩
ISSN: 2045-2322
Popis: In the days to weeks following an earthquake, landslides can display specific post-seismic motions, including delayed initiations and post-seismic relaxations. These motions have an uncertain origin, sometimes attributed to specificities of the landslide basal interface or to fluid transports in the landslide basal shear zone. Here we address this question, by documenting the co- and post-seismic motions of slow-moving landslides accelerated by the Gorkha earthquake (Mw 7.8, 25/04/2015, Nepal). We detect 11 slow-moving landslides over an area of 750 km$$^2$$ 2 in the near field of the earthquake, and monitor their motions thanks to a time-series of Pléiades optical satellite images and SAR Sentinel-1 images. The post-seismic landslide motions are much larger than the co-seismic ones, reaching up to $$34 \,\pm\, 0.6$$ 34 ± 0.6 m accommodated over 2 months. A delayed initiation of several days (> 4 days) is also measured for at least two of the landslides. We analyze our findings in regards with all the previous observations on slow-moving landslides accelerated by earthquakes, and propose that the post-seismic motions are caused by diffusion of groundwater from co-seismic material contraction up to the landslide basal shear zone or from internal landslide reconfiguration. Our observations strongly suggest the main control of the hydrology in the landslide processes under seismic forcings.
Databáze: OpenAIRE
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