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

Objectives: On 18 December 2023, an MS 6.2 earthquake struck the Jishishan County, Linxia Prefecture, Gansu Province, China. As the largest earthquake to hit this region since seismic record, the occurrence of the 2023 Jishishan earthquake provides a race opportunity to improve our understanding of the seismogenic structure and rupture behavior of the regional active fault. Methods: In this study, we utilize Sentinel-1A Interferometric Synthetic Aperture Radar 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 LJSF. Coseismic Coulomb stress changes indicate a high seismic risk at the middle segment of the eastern branch fault of the LJNF, the southern segment of the eastern branch fault of the LJSF and the western segment of the XLNF.