Strain accumulation along various faults in the Kashmir Himalaya from InSAR

Abstract

We are using InSAR time-series analysis to measure the interseismic deformation across various faults of the Kashmir Himalaya. Active faults reaching the surface include the Main Boundary Faults, Bagh-Balakot Fault, which ruptured in the 2005 Kashmir earthquake (Mw 7.6), Jhelum Fault, Reasi Thrust and intra-Kashmir basin faults. We concentrate on these shallow faults that are closest to the people living in Kashmir. The Main Boundary Faults and other faults likely connect to the Main Himalayan Thrust (MHT) that is the plate-boundary megathrust beneath Kashmir and the rest of the Himalayas. The MHT has been suggested as a possible source for Mw 8 to Mw 8.5 earthquakes in this area. We have processed interferometric pairs from the Japan Aerospace Exploration Agency ALOS-2 L-band (24 cm wavelength) Synthetic Aperture Radar (SAR) wide-swath (ScanSAR) data acquired between 2015 and 2020. Initial interferometric SAR (InSAR) processing was carried out using the alos2App application of the InSAR Scientific Computing Environment (ISCE2) package, with ionospheric corrections enabled. We found that many scenes acquired in the winter form pairs that have low coherence due to snow cover in the High Himalayas and Pir Panjal Range. We also found that phase unwrapping in the mountains was improved by taking 10 range and 56 azimuth looks from the full-aperture ScanSAR for an effective resolution of about 200 meters. We are running a co-registered stack processing of the ALOS-2 SAR data, with selfconsistent ionospheric corrections estimated using the split-spectrum method, using the new alosStack application of ISCE2 package to carry out time-series InSAR analysis, using an opensource Python toolbox, MIntPy.