Deformation Process and Mechanism of the 2025 Ms 6.8 Dingri Earthquake in Southern Tibet constrained by GNSS and InSAR

The 2025 M_W 7.0 Dingri earthquake in southern Tibet provides a unique opportunity to investigate normal-faulting mechanisms within an active rift zone. By integrating geodetic (GNSS and InSAR) and field observations, we investigate the event’s interseismic and coseismic deformation and quantify the impact of the 2015 M_W 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. (2) The coseismic slip model reveals a graben structure formed by two near N-S striking normal faults, with a maximum slip of 4.1 m and a seismic 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) Critically, deformation analysis demonstrates that the 2015 Gorkha earthquake significantly 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, rift evolution, and deep crustal processes in southern Tibet.