Fault coupling and creep control landslide distribution in southeastern Tibet, China, from SAR interferometry

Landslides pose a significant hazard to lives and property worldwide. Understanding the triggering factors of landslides provides essential information for hazard mitigation. While much research has focused on the effects of precipitation, underground mining, water level changes, and earthquakes on landslides, there remains a gap in understanding the impact of long-term and subtle tectonic interseismic motion, particularly over large-scale areas. Interferometric Synthetic Aperture Radar (InSAR) is widely used in landslide research, effectively detecting wide-area landslides and monitoring high-risk individual landslides. Additionally, it provides insights into the triggering factors and failure mechanisms of landslides. This study focuses on the Chuandian block area in southeastern Tibet, China, an area characterized by active tectonic motion.

First, we proposed an automated method for detecting landslides from wide-area InSAR deformation rates, utilizing density clustering and minimum boundary extraction. Using this method, potential landslides were successfully detected in the Chuandian block. The relationship between landslide distribution and the shallow coupling and creep of faults in the Chuandian block was then comprehensively analyzed based on the results of wide-area landslide distribution and interseismic deformation. Specifically, three-dimensional deformation along the Ganzi-Yushu and Xianshuihe faults was monitored using multi-orbit Sentinel-1 SAR and GNSS observations. An elastic dislocation model was also applied to invert shallow creep along these faults. Finally, the development patterns of landslides under the combined influence of internal and external dynamics were summarized. In high-creep areas along the faults, long-term and subtle interseismic motion of the shallow surface led to significant fissure development and structural deterioration in rock and soil, creating internal conditions conducive to landslide formation. External dynamics, including river erosion, precipitation, freezing, and thawing, further accelerated landslide development. Our findings underscore the importance of understanding the relationship between interseismic motion and landslides to enhance knowledge of how tectonic processes influence landslide formation and to support improved hazard mitigation strategies.