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

P. Lacroix, Théo Gavillon, Clément Bouchant, J. Lavé, J. Mugnier, Samir Dhungel, F. Vernier

Scientific Reports, 2022

30 citations

Abstract

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 km2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^2$$\end{document} 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±0.6\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$34 \,\pm\, 0.6$$\end{document} 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…

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