LANDSLIDES TRIGGERED BY THE 2015 GORKHA, NEPAL EARTHQUAKE

Abstract. The 25 April 2015 Gorkha Mw 7.8 earthquake in central Nepal caused a large number of casualties and serious property losses, and also induced numerous landslides. Based on visual interpretation of high-resolution optical satellite images pre- and post-earthquake and field reconnaissance, we delineated 47,200 coseismic landslides with a total distribution extent more than 35,000 km², which occupy a total area about 110 km². On the basis of a scale relationship between landslide area (A) and volume (V), V = 1.3147 × A^1.2085, the total volume of the coseismic landslides is estimated to be about 9.64 × 10⁸ m³. Calculation yields that the landslide number density, area density, and volume density are 1.32 km⁻², 0.31 %, and 0.027 m, respectively. The spatial distribution of these landslides is consistent with that of the mainshock and aftershocks and the inferred causative fault, indicating the effect of the earthquake energy release on the pattern on coseismic landslides. This study provides a new, more detailed and objective inventory of the landslides triggered by the Gorkha earthquake, which would be significant for further study of genesis of coseismic landslides, hazard assessment and the long-term impact of the slope failure on the geological environment in the earthquake-scarred region.