Seismic and Landslide Hazard Assessment Using Iterative Observation DInSAR: Insights from the 2022 Mw 6.1 Pasaman Earthquake, Indonesia

Earthquakes, particularly those along active tectonic boundaries such as Indonesia’s Semangko Fault, often trigger cascading hazards like landslides. Accurate monitoring of earthquake-induced surface deformation and secondary hazards remains critical for disaster risk reduction, especially in mountainous regions. Using a multi-sensor geospatial approach, this study investigates the spatial and temporal evolution of ground deformation and landslide activity associated with the 2022 Mw 6.1 Pasaman earthquake. We apply an Iterative Observation Differential Interferometric Synthetic Aperture Radar (IO-DInSAR) technique to Sentinel-1A imagery, enabling the reconstruction of true vertical displacements across pre-seismic, co-seismic, and post-seismic phases. The results reveal progressive interferometric fringe development and vertical deformation preceding the mainshock, followed by widespread post-seismic landslides, particularly on the slopes of Mount Talamau. Coherence change detection (CCD), Normalized Difference Vegetation Index (NDVI) analysis from Sentinel-2, and derived landslide velocity models further corroborate spatial patterns of slope failure. Validation against CORS geodetic data yields a root mean square error (RMSE) of 0.009 m, confirming the reliability of vertical displacement estimates. Unlike traditional DInSAR, the IO-DInSAR approach captures temporally continuous deformation patterns, offering deeper insights into the develcopment of earthquake-related instability. These findings highlight the utility of iterative DInSAR analysis for enhancing our understanding of cascading seismic hazards and inform early warning strategies in tectonically active regions.