Dual-Fault Rupture and Thermo-Mechanical Setting of the 2025 Dingri Earthquake (Southern Tibet)

Abstract The southern Tibetan Plateau has been spared from the occurrence of normal faulting earthquakes exceeding Mw 7.0 for over half a century. On 7 January 2025, the Mw 7.01 Dingri earthquake occurred on the southwestern branch of the Xainza-Dinggye rift, southern Tibet, which offers an opportunity to understand the rift-related seismogenic mechanisms and regional deformation dynamics. We integrate finite-fault inversion, multiple-point-source (MPS) modeling, and slowness-enhanced backprojection imaging to investigate the detailed rupture kinematics of this event. Our results show that this rare event is characterized by dual-fault rupture involving normal slip on the main fault and strike-slip motion on the secondary fault. The obtained slip model and MPS modeling delineate three distinct subevents, highlighting significant rupture complexity. Intense high-frequency radiators, spatially aligned with coseismic slip edges, underscore the brittle–ductile transition. The 2025 Dingri event follows a linear scaling relationship between the rupture length (L) and seismogenic thickness (z), with a characteristic L/z ratio of ∼3.2 for continental normal-faulting earthquakes. The substantial earthquake size might be attributed to the unique thermo-mechanical condition of faults, evidenced by aeromagnetic, seismic tomography, and resistivity data. The interaction between strong upper-middle crust and weak lower crust, due to fluid intrusion from the mantle, likely promotes the occurrence of the 2025 Dingri earthquake.