Geomorphic and geologic controls of geohazards induced by Nepal’s 2015 Gorkha earthquake

J S Kargel, G J Leonard, D H Shugar, U K Haritashya, A Bevington, E J Fielding, K Fujita, M Geertsema, E S Miles, J Steiner, E Anderson, S Bajracharya, G W Bawden, D F Breashears, A Byers, B Collins, M R Dhital, A Donnellan, T L Evans, M L Geai, M T Glasscoe, D Green, D R Gurung, R Heijenk, A Hilborn, K Hudnut, C Huyck, W W Immerzeel, Jiang Liming, R Jibson, A Kääb, N R Khanal, D Kirschbaum, P D A Kraaijenbrink, D Lamsal, Liu Shiyin, Lv Mingyang, D McKinney, N K Nahirnick, Nan Zhuotong, S Ojha, J Olsenholler, T H Painter, M Pleasants, K C Pratima, Q I Yuan, B H Raup, D Regmi, D R Rounce, A Sakai, Shangguan Donghui, J M Shea, A B Shrestha, A Shukla, D Stumm, M van der Kooij, K Voss, Wang Xin, B Weihs, D Wolfe, Wu Lizong, Yao Xiaojun, M R Yoder, N Young

The Gorkha earthquake (M 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9,000 and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes' induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision makers. We mapped 4,312 co-seismic and post-seismic landslides. We also surveyed 491 glacier lakes for earthquake damage, but found only 9 landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.