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

TLDR

The 7.8‑magnitude Gorkha earthquake on 25 April 2015 struck South Asia, killing ~9 000 people and damaging a vast region. The study aimed to map earthquake‑induced geohazards in Nepal and China and evaluate how geomorphic, tectonic, and lithologic factors control landslides. Researchers leveraged a large campaign of responsive satellite data acquisitions to conduct a satellite image survey of the disaster zone. They mapped 4 312 coseismic and postseismic landslides, surveyed 491 glacier lakes (finding only nine impacted and no outburst evidence), and showed that landslide density correlates with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions, thereby informing timely response and decision‑making.

Abstract

The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people 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 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine 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.