Complex Multifault Rupture During the 2016–2025 Dingri Earthquakes, Southern Tibetan Plateau, Unraveled by Multisource InSAR Observations
Jiuyuan Yang, Yangmao Wen, Caijun Xu, Qingfeng Hu
Abstract
Abstract During 22 May 2016 to 7 January 2025, three significant earthquakes (2016 Mw 5.4, 2020 Mw 5.7, and 2025 Mw 7.1 Dingri earthquakes) progressively ruptured the Shenza-Dingjie fault system, southern Tibetan plateau, effectively closing a remarkable seismic gap. We use Sentinel-1, Lutan-1, and Advanced Land Observation Satellite-2 Synthetic Aperture Radar images to extract coseismic deformation of the three events and the first-month postseismic deformation of 2025 event. Coseismic modeling demonstrates that the 2025 earthquake ruptured one west-dipping strike-variable moderate-angle main normal fault while the 2016 and 2020 earthquakes activated two shallow-dipping secondary normal faults, highlighting a complex synthetic–antithetic seismogenic structure. Further time-dependent postseismic analysis not only documents prominent postseismic signal of up to ∼5 cm closely following 2025 earthquake, but also resolves discrete coseismic signals of ∼3–4 cm related to three Ms≥4.6 aftershocks. By the comprehensive analysis of geodetic inversion, fault distribution, and topography, we deduce that 2025 earthquake nucleation is likely driven by elevated gravitational potential energy within the southern Tibetan plateau extensional regime.