Research on the Seismogenic Mechanism of the 2025 Mw = 6.9 Dingri Earthquake

Two earthquakes greater than Mw 5.5 occurred in Dingri County, Tibet, between 2020 and 2025. Whether a triggering relationship exists between them remains debated. Therefore, in this study, we examine the kinematic mechanisms of the two events and seismogenic faults, as well as the post-seismic Coulomb stress changes. The results show that the maximum slip of the 2020 Dingri earthquake is 1.3 m at a depth of about 3.55 km, with a seismic moment of 6.53 × 1017 N·m, equivalent to an Mw = 5.8 earthquake. Regarding the 2025 earthquake, the maximum slip of F1 fault is 5.1 m at a depth of about 4.5 km, and the peak slip of the F2 fault is 0.46 m at a depth of about 2.5 km. With a seismic moment of 2.82 × 1019 N·m, the 2025 earthquake matches an Mw = 6.9 earthquake. The Dengmecuo fault exhibits a deformation rate of about 14.4 mm/yr, and the southern section of the fault is nearly locked before the 2025 earthquake, with a slip deficit of about 13.5 mm/yr. The Coulomb stress change five years after the 2020 earthquake is 10,700 Pa, which exceeds the threshold for triggering subsequent seismic activity, indicating a triggering relationship between the two earthquakes.