InSAR phase gradient reveals fault-zone controls on the spatial distribution of slow-moving landslides in the active orogenic region of Hazara-Kashmir, Pakistan

Abstract

Slow-moving landslides play important roles in the landscape evolution and hazards planning. Studies along some strike-slip faults have shown that the geological structures and bed-rock lithology significantly contribute the distribution of slow-moving landslides. However, controls on the distribution of slow-moving landslides are poorly constrained in active orogenic regions, hindering our understanding of its role in the rapid orogenic process. The Hazara Kashmir Syntaxis in Pakistan is such a prominent geological structure of lesser Himalaya, where the inventory of slow-moving landslides is scarce. Here, we attempt the interferometric synthetic aperture radar phase-gradient stacking coupled with a deep-learning system to provide the first slow-moving landslides inventory (1066 presently active landslides, 2016–2023) in the Hazara-Kashmir region. Along with optical imagery and field investigations, we analyse the impacts of fault structures, bed-rock lithology, topography along with spatial distribution of earthquake and precipitation on the distribution of these slow-moving landslides. We find that 33% of the detected slow-moving landslides are distributed within 1000 m to active faults, and show a decreasing trend moving away from fault zones. This pattern strongly suggests that the active thrusting faults in this region significantly controls the distribution of slow-moving landslides, while topography and precipitation show less impacts. Our study reveals the spatial distribution of slow-moving landslides in a tectonic complex region with rapid orogenic process, and thus shows potential implications in geomorphology modelling and hazards evaluation for many less-monitored, contemporary uplifting high-mountain regions.