Abstract:
High-precision coseismic surface deformation is a key parameter for understanding shallow fault rupture mechanisms and accurately assessing seismic hazard. For the first time, GaoFen-7 imagery and Digital Surface Model (DSM) differencing technique were employed to obtain high-resolution coseismic surface vertical deformation associated with the January 7, 2025 Dingri Ms6.8 earthquake in Tibet, China. The revealed surface trace of the seismogenic fault and vertical deformation characteristics coincide with the Dengmocuo Fault dominated by normal faulting, indicating that the earthquake was a normal-faulting event. This earthquake generated a 42-kilometer-long surface deformation zone, with distinct segmentation in both deformation amplitude, gradient and width related to fault geometric complexity and dynamic rupture process. The deformation zone is divided into three segments from north to south: the N22°E-trending Zhananla segment, the N160°E-trending Dengmocuo Lake segment, and the N25°E-trending Cuoguoxiang Segment. Pronounced deformation occurred in the Zhananla segment, reaching a maximum vertical displacement of approximately 2.97±0.2m meters. The surface deformation observed along the Dengmocuo Lake segment is the least pronounced, potentially attributable to a change in the fault's orientation. The width of the coseismic deformation zone on fault segments spans 100 to 150 meters, suggesting that the diffuse deformation occurring within a limited volume surrounding the faults may be overlooked or underestimated, so it is necessary to carry out high-precision continuous monitoring.