Coseismic deformation and slip distribution of the 2023 Jishishan M_W6.0 earthquake based on InSAR measurements

An M_W6.0 earthquake struck Jishishan County in Linxia Prefecture, Gansu Province, on December 18, 2023. In this research, Sentinel-1A satellite radar observations were used to obtain the field of coseismic deformation of the Jishishan earthquake in 2023, and the geometric and fine slip distribution of the seismogenic fault were inverted using this as a constraint. The results show that the earthquake is characterized by thrust movement. The coseismic slip distribution results show that the maximum slip of this earthquake is 0.3 m. The Coulomb stress distribution shows that the whole section of the southern edge of Lajishan fault, the NWW trending segment of the northern edge of Lajishan fault and its NNW trending segment to the south of the epicenter, the northern edge of the West Qinling fault and the segment to the east of the epicenter of the Daotanghe Linxia fault are under stress loading, which indicates an increase in the potential risk of earthquakes. This research discussed the seismogenic characteristics of earthquakes and the tendency of faults. We speculate that the Jishishan earthquake is the result of the joint action of regional faults and tectonic stress. Based on the observation of seismic data, geodesy, and other geological and geophysical data, we believe that the earthquake was caused by the activation of weak areas under the crust by the local stress from the driving mechanism of the northeast expansion of Qinghai-Xizang Plateau. The seismogenic fault of this earthquake is more likely to be northeast dipping under the comprehensive consideration of various factors, which occurred on the concealed fault belonging to the eastern edge of the Jishishan fault zone.