Coseismic Surface Displacements and Source Model of the 2024 Mw 7.0 Wushi (Xinjiang, China) Earthquake Revealed by InSAR Observations

Objectives: On 23 January 2024, an Mw 7.0 earthquake struck Wushi County (Xinjiang, China). It was the largest earthquake that occurred along the Maidan-Shayilamu fault of the Tianshan Seismic Belt in the last two decades, which provided an opportunity to further examine the rupture behavior and tectonic activity of the fault system in the Tianshan Seismic Belt. Methods: In this study, Interferometric Synthetic Aperture Radar (InSAR) was used to retrieve coseismic surface deformation from Sentinel-1A images. The multipeak particle swarm optimization was employed to invert for fault geometry parameters and subsequently obtained the refined slip distribution based on a bounded-variable least-squares algorithm. Finally, the static Coulomb failure stress change (ΔCFS) was calculated to assess regional seismic hazards. Results: The earthquake led to a maximum line of sight uplift displacement of ~74 cm and a maximum LOS subsidence displacement of ~14 cm. The event had a NNW-dipping fault with a dip of 55°, a strike of ~230°, and a rake of ~42°, indicating that this earthquake was a thrust event with a leftlateral slip component. The slip was concentrated mainly at depths of 8-18 km. The maximum slip was 4.3 m, occurring at a depth of ~10.2 km. The total released moment was 4.25×1019 N·m, equivalent to a moment magnitude Mw 7.05. Conclusions: Our modeling results together with previous geological research suggest that the seismogenic fault is a secondary fault of the MaidanShayilamu fault zone. ΔCFS results indicate high seismic risks in Kuokesale fault region, Dashixia fault region, and the Tuoshigan fault region northwest of the epicenter, which special attention should be paid to.