Mapping and Monitoring Earthquake-Induced Unstable Slopes in Pakistan by Means of MT-InSAR

The study tested interferometric point target analysis (IPTA) on Sentinel-1A terrain observation with progressive scans SAR (TOPSAR) images between January 2016 and December 2018 to analyze the spatio-temporal distribution of earthquake-induced active unstable slopes in the surrounding region of the epicenter of the 2005 Kashmir earthquake in northern Pakistan. The results reveal dozens of unstable slopes with an average deformation rate varying between -35 mm/year and 10 mm/year along the line of sight (LOS) direction. A large number of unstable slopes showed relatively faster movements, with a rate between -35 and -25 mm/year. The study also found that the temporal behaviors of downslope movement are correlated with local precipitation. Rainwater finds its pathways through joints and cracks of rocks, speeding up slope destabilization. The study emphasizes the need for continuous monitoring and investigation of earthquake-induced slope stability to accurately delineate and investigate the sliding surfaces of unstable slopes with multi-sensor and multi-orbit data for effective mitigation measures.