An Assessment of Earthquake-Induced Landslides Distribution in Nepal Using Open-Source Applications on Sentinel-1 Tops SAR Imagery

The effects of landslide disasters are extremely severe, resulting in significant economic damage and a high number of fatalities on a global scale. In the event of a disaster of this magnitude, a swift and reliable disaster information is crucial. This is usually very tasking activities and expensive using proprietary application and data. This study therefore demonstrates the usability of opensource application and free satellite data on an assessment of earthquake induced landslide using data and applications sourced from European Space Agency (ESA) Copernicus Open Access Hub. A Differential Interferometric Synthetic Aperture Radar (DInSAR) technique, which is more advanced earthquake assessment tool was used to obtain morphological changes via-a-vis the vertical displacement produced during Gorkha earthquake of April 25, 2015, in Nepal. In the study, a single interferogram of the two repeat pass SAR data for a DInSAR process was applied over an area of 128 km². A pair of SAR image with a temporal baseline of 144 days and perpendicular baseline of 122.51 meters were used. Three landslide locations were evaluated. The vertical displacements using DInSAR ranges from -0.23 (moving away from satellite) to 0.24 m (movement towards satellite). The simulated morphological values compared well with obtained google earth images captured at during the period of the disaster event.