Northward rupture and early afterslip of two graben-bounding normal faults during the 2025 Dingri earthquake of Tibet

Abstract

The Mw 7.0 Dingri earthquake, the largest documented normal-faulting event in southern Tibet, struck within the NS-trending Dinggye-Xainza Rift system. Here we combine field observations, high resolution optical and synthetic aperture radar imagery and seismic waveforms to determine the three-dimensional coseismic deformation field, coseismic rupture processes and early postseismic deformation mechanisms of the event. We find that the rupture propagated unilaterally northward from the earthquake hypocenter, concurrently activating two graben-bounding faults. The main rupture was concentrated on the Dengmo Co fault causing a maximum subsidence of 3 m and a 25-km-long rupture trace at the surface. The first four-months postseismic deformation is dominated by shallow afterslip, which exhibits spatial overlap with the coseismic slip zone. Our observations provide important insights into the rupture kinematics and strain partitioning within the Dinggye-Xainza Rift, offering a valuable framework for understanding continental extensional tectonics and seismic cycle processes in similar southern Tibet grabens.