Geomorphic and Geologic Controls of Geohazards Induced by Nepal’s 2015 Gorkha Earthquake

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 geologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision makers. We mapped 4312 co-seismic and post-seismic landslides and surveyed 491 glacier lakes for earthquake damage, but found only 9 landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities are correlated with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.