Seismogenic structure of Jishishan, Gansu 2023 M_w6.0 earthquake constrained by InSAR Data and Earthquake sequence

The M_w6.0 earthquake occurred in Jishishan County, Gansu Province, China, on December 18, 2023. Methods: The interferometric synthetic aperture radar (InSAR) technique was utilized to process Sentinel-1A radar images from both ascending and descending tracks to retrieve high resolution coseismic surface displacement maps for these Jishishan earthquakes. The coseismic surface displacements and the double difference relocation algorithm of the earthquake sequence were then inverted to determine the fault geometry parameters and the non-uniform fault slip distributions with a dislocation model in an elastic half-space. Results: The results show that the 2023 Jishishan earthquake was a reverse event on a buried fault with a maximum surface displacement of 7.0 cm and 6.8 cm on the ascending and descending tracks, respectively. The depth of the seismic source is mainly concentrated at 6-15 km, which is obtained by the joint small-seismic fault-plane fitting and the fault-geometry parameter inversion. The depth of the earthquake source is mainly concentrated in 6-15km, and the seismic fault tends to NE, strikes at 323°, and dips at 50°. the rupture is mainly concentrated in the depth range of 4-11km underground, and the maximum slip amount of 0.2m occurs at 5.7km underground, Conclusions: we prefer this eqrthquake occurred on Southern edge of Lajishan fault with a NNW-trending, east-dipping, thrust fault. By calculating the coulomb failure stress changes (ΔCFS), it indicates an increased seismic risk for the future in the southern margin of Laqishan Fault, the northern margin of Laqishan Fault, and the eastern segment of Daotanghe-Linxia Fault after the 2023 earthquake in Jishishan.