InSAR coseismic deformation, fault slip inversion and coulomb stress evolution of the Xizang Dingri earthquake on January 7, 2025, China
摘要
On January 7, 2025, an Ms 6.8 earthquake struck Dingri County, Shigatse, Tibet Autonomous Region, causing severe casualties and property losses. This study utilized Sentinel-1 satellite data and Interferometric Synthetic Aperture Radar (InSAR) technology to obtain the co-seismic surface deformation field, invert the fine geometric parameters and slip distribution of the seismogenic fault, and calculate regional co-seismic Coulomb stress changes. Results show that both ascending and descending orbit radar satellites captured the co-seismic deformation, with a field range of 160 km × 100 km and surface rupture of the seismogenic fault. The maximum Line-of-Sight (LOS) deformations were -1.73 m (ascending) and -1.26 m (descending), while azimuth deformations reached -1.11 m and -1.10 m, respectively. Three-dimensional deformation revealed significant subsidence (1.69 m vertical) on the west-side hanging wall and uplift (0.22 m max) on the east-side footwall, indicating normal fault movement along the Dengmocuo Fault. Inversion constrained by InSAR data showed the fault is 32 km long, 14 km wide, with a strike of 187°, dip angle of 56°, and slip angle of -68°, rupturing mainly at 0–16 km depth. The maximum slip was 3.93 m, seismic moment 4.03 × 101⁹ N·m, and moment magnitude Mw 7.04. More than 80 aftershocks with M ≥ 3.0 near the Dengmocuo fault were mainly caused by the increase in Coulomb stress caused by the Dingri Mw7.04 earthquake. Considering the influence of historical earthquakes and background tectonic stress, the Coulomb stress change value of the Dingjie County seat will increase by 0.01 MPa after 2047, indicating the possibility of earthquakes occurring. The increase in Coulomb stress change value in the county seat of Gangba is greater than 0.3 MPa, indicating a high possibility of earthquake occurrence.