Deformation Process and Mechanism of the 2025 <i>M</i> w 7.0 Dingri Earthquake in Southern Tibet Revealed by GNSS and InSAR

Summary The 2025 Mw 7.0 Dingri earthquake in southern Tibet provides a unique opportunity to investigate normal-faulting mechanisms within an active rift zone. Integrating geodetic (Global Navigation Satellite System and Interferometric Synthetic Aperture Radar) and field observations, we characterize the event’s interseismic and coseismic deformation. This integrated analysis allows us to invert a detailed fault slip model and quantitatively evaluate the triggering effect of the 2015 MW 7.8 Gorkha earthquake. Our principal findings are: (1) The epicentral extensional strain rate is (1.5 ± 0.2) × 10−8/yr, notably lower than in the northern aftershock zone, indicating strain partitioning difference. (2) The coseismic slip model reveals a graben structure formed by two near north-south striking normal faults, with a maximum slip of 4.1 m and a geodetic moment of 4.2 × 1019 N·m. (3) Field measurements confirm a segmented surface rupture, where the central segment’s vertical slip (2.1–2.2 m) aligns precisely with the InSAR-derived line-of-sight deformation maximum (2.04 m), validating the geodetic model. (4) Deformation analysis demonstrates that the 2015 Gorkha earthquake promoted the rupture of the Dingri earthquake, potentially accelerating its seismic cycle by ∼20 years. This event exemplifies rift propagation along the Shenzha-Dingjie system and offers crucial insights into post-seismic stress transfer and deep crustal processes in southern Tibet.