The Complex Three Dimensional Fault Model and Slip Distribution of The 2025 M_W 7.1 Dingri Earthquake

The Dingri earthquake， which occurred in Dingri County within the Southern Tibet Rift System， represents the only Mw 7+ normal faulting event in this region to be comprehensively recorded by modern instrumentation. In this study， we integrated coseismic rupture observations and relocated aftershock data to develop a detailed three-dimensional fault model. Utilizing this model， in conjunction with coseismic deformation data derived from InSAR， we further constrained the coseismic slip distribution. Our findings indicate that the earthquake ruptured three faults: the Dengmecuo Fault (F1) and two subsidiary faults， F2 and F3. The primary fault， F1， dips westward， exhibiting a steeper dip in the shallow section and a more gradual dip at depth， with the northern segment dipping more steeply than the southern segment. The east-dipping F2 fault intersects F1 at a depth of approximately 20 km and connects with the west-dipping F3 fault at shallower depths. This event is characterized as a normal faulting earthquake with a significant left-lateral strike-slip component， exhibiting a maximum slip of 4.1 meters. The occurrence of this earthquake provides critical insights into the tectonic evolution and deformation mechanisms of the Southern Tibet Rift System.