Coseismic Deformation and Fault Slip Distribution of the January 7,2025,Dingri MW 7.1 Earthquake

Zhang Xu; Hong Shunying; Dong Yanfang; Liu Tai; Yang Junyan; He Junyu

doi:10.3799/dqkx.2025.072

Abstract：On January 7,2025,an MW7.1 earthquake struck Dingri County,Shigatse City,Xizang Autonomous Region.The epicenter was located at the intersection of the southern segment of the Shenzha-Dingjie rift fault system and the South Tibetan detachment system,near the Dengmocuo fault.To investigate the seismogenic mechanism,slip distribution,and Coulomb stress disturbances of the earthquake,this study firstly utilized the Sentinel-1A data to obtain the coseismic deformation fields by InSAR(interferometric synthetic aperture rader)and POT(pixel offset tracking)techniques.Then,we employed the SDM program to invert the fault coseismic slip-distribution,and subsequently calculated the coseismic Coulomb stress disturbances with variable depth.The results indicate that the coseismic deformation of the Dingri earthquake is dominated by subsidence.The seismogenic fault strikes nearly north-south,with a dip angle of～60°.The inverted coseismic slip-distribution suggests that the major rupture zone(slip>1 m)extends～40 km in length and～14 km in width.The maximum slip is approximately 4.45 m,occurring at a depth of～4.33 km.The average rake angle is approximately ‒76.81°,indicating that this earthquake was predominantly a normal faulting event with a slight left-lateral strike-slip component.Taken the shear modulus at 30 GPa,the inverted seismic moment is about 3.53×1019 N·m,equivalent to the moment magnitude MW7.0.Aftershocks predominantly happened around the periphery of the major slip zone.Additionally,the coseismic and postseismic Coulomb stress disturbances suggest significant increases(>10 kPa)in the southern segment of Shenzha-Dingjie fault,the eastern segment of Zanda-Lhaze-Qongdojiang fault,the central-eastern segment of Dagyiling-Ngamring-Rinbung fault,and the central segment of Yarlung Tsangpo fault.The future seismic hazards on these fault segments warrant heightened attention.