Coseismic Deformation and Coulomb Stress Changes of the Ms6.8 Dingri, Xizang Earthquake

On January 7, 2025, a magnitude 6.8 normal-fault earthquake struck Dingri County, Xizang, causing significant damage and triggering numerous aftershocks in the southern Tibetan Plateau. In this study, we employ finite element modeling to calculate coseismic deformation and Coulomb stress changes, aiming to investigate the mechanisms of aftershock triggering within the regional tectonic setting. Results indicate that the surface displacement field aligns with the tectonic stress background, showing up to 3 m of vertical deformation concentrated in the northern fault segment. Coulomb stress calculations reveal that the source area and surrounding areas showed predominantly negative stress changes, suggesting that the mainshock released part of the regional stress. Nevertheless, abundant aftershocks still occurred, which we attribute to postseismic afterslip. In contrast, the northern area of the fault showed positive Coulomb stress changes, with most aftershocks occurring within a triggering threshold of 0.01 MPa, suggesting influences form coseismic stress loading. Overall, our analysis of the rupture characteristics, coseismic stress, and aftershock activity suggests that coseismic stress changes may be a key controlling factor in the evolution of postseismic activity.