Land Subsidence Monitoring in the Kathmandu Basin, Before and After MW 7.8 Gorkha Earthquake, Nepal by Sbas-Dinsar Technique

In recent years, subsidence due to excessive groundwater withdrawal is a major problem in the Kathmandu Basin. In addition, on 25 April 2015, the basin experienced large crustal displacements caused by Mw 7.8 Gorkha earthquake. Consequently, the effects of co-seismic deformation could affect the temporal and spatial nature of anthropogenic subsidence in the basin. In this study, we applied Small Baseline subset (SBAS)-DinSAR technique to estimate the spatio-temporal displacements in the basin, before and after the earthquake. 16 ALOS-1 L-band and 20 Sentinel-1 C-band SAR data are used for measuring pre- and post-seismic subsidence velocity, respectively. We found that the subsidence velocity in the central part of the basin is increased after the mainshock.