Seismogenic Fault Structure of the 2023 Ms 6.2 Jishishan （Gansu,China） Earthquake Revealed by InSAR Observations

Objectives On December 18, 2023, an Ms 6.2 earthquake struck the Jishishan County, Gansu Province, China. As the largest earthquake to hit this region since seismic record, the 2023 Jishishan earthquake provides an opportunity to improve our understanding of the seismogenic structure and rupture behavior of the regional active fault.

Methods We utilize Sentinel-1A interferometric synthetic aperture radar (InSAR) data to extract the coseismic surface deformation associated with this earthquake and investigate the seismogenic fault structure.

Results and Conclusions Geodetic inversion result shows that both the SW-dipping and NE-dipping fault models can fit the coseismic InSAR observations better. By a joint analysis of the aftershocks, regional fault kinematics and coseismic interferograms, we infer that the 2023 Jishishan earthquake ruptured the NE-dipping seismogenic fault, which may be a buried branch fault belonging to the south Laji Mountain fault. Coseismic Coulomb stress changes indicate a high seismic risk at the middle segment of the eastern branch fault of the north Laji Mountain fault, the southern segment of the eastern branch fault of the south Laji Mountain fault and the western segment of the northern margin of the western Qinling fault.