Asymmetric Y-Shaped Structural Rupture of the 2025 Mw 7.1 Tingri, Southern Tibet, Earthquake

Abstract Understanding the seismogenic structures of large earthquakes is critical for constraining regional tectonic frameworks and improving future seismic hazard assessments. The 2025 Mw 7.1 Tingri earthquake in southern Tibet, China, a significant event following the 2020 Mw 5.7 earthquake, occurred at the junction of the Northern Himalaya and the Xainza-Dinggye fault system. To investigate the local structural complexities, we processed three Sentinel-1A Synthetic Aperture Radar (SAR) tracks (both ascending and descending) using Interferometric SAR (InSAR) and pixel offset tracking (POT) to derive the coseismic surface displacement field. The InSAR results reveal a maximum line-of-sight (LoS) displacement of −1.37 m, whereas the POT results identify two distinct fault ruptures associated with the 2025 event. By inverting the coseismic deformation field with an elastic half-space model, we obtained the fault rupture model, which shows that the 2025 earthquake ruptured an asymmetric, segmented Y-shaped fault system, with slip dominated by normal faulting and a peak slip magnitude of 4.9 m. The Coulomb stress change results further indicate that the 2025 earthquake rupture was primarily driven by the ongoing extensional tectonics of the regional rift system and may have been facilitated by static stress transfer from the 2020 Tingri earthquake. These results highlight the mechanical link between successive large events in complex fault systems and provide new constraints on the seismotectonic processes of the North Himalayan rift zone.