Spatial Relations of Earthquake Induced Landslides Triggered by 2015 Gorkha Earthquake Mw = 7.8

This paper presents the results of an extensive mapping of co-seismic landslides triggered by the 2015 Gorkha earthquake in central Nepal. More than 19,332 landslides have been identified covering 61.5 km² of land in about 20,500 km² area of investigation using Google Earth imagery. Their spatial distribution characteristics and relation to the triggering mechanism is studied. Interesting regional localization and angular distribution characteristics, more controlled by the rupture directivity is observed. Seismic, geomorphic and lithological parameters that induce susceptibility to their occurrence is studied using two indices of landslide concentration: Landslide Area Percentage (LAP) and Landslide Number Percentage (LNP) in comparison with % area of each parameter classes. Positive correlation with the chosen triggering parameters are observed but there are some significant differences in the parameter values and distribution plots to co-seismic landslides in other parts of world. These results provide valuable information about the slope response characteristics in case of seismic activation in thrust faulting Himalayan landscapes, and this is important in further researches on co-seismic landslide prediction models for mountainous settlements, sediment yield studies and cascading landslide disasters after major earthquakes.