Source Parameters and Seismogenic Fault Model of the 2024 Mw 7.0 Wushi (Xinjiang, China) Earthquake Revealed by InSAR Observations

Abstract

On January 23, 2024, an M_w 7.0 earthquake struck Wushi County, Xinjiang. This study used Sentinel-1A data to obtain the co-seismic deformation field utilising the InSAR technique in the Wushi area. An earthquake uniform slip model was determined using a Bayesian algorithm. The earthquake fault slip distribution was inverted using the steepest descent method (SDM), and the seismic impact on neighbouring faults was evaluated using the Coulomb instability criteria. The maximum displacement was approximately 76 cm in line of sight (LOS) direction as observed using ascending Interferometric Synthetic Aperture Radar (InSAR) data. The fault is responsible for earthquake trends towards the northwest, with a dip angle of approximately 62.8°, strike of approximately 229°, and slip angle of approximately 49.8°, and it displays a compressive and sinistral strike-slip motion. The fault parameters and spatial position were aligned with the Maidan Fault at the southern margin of the Tianshan Mountains. Coulomb stress analysis revealed that regions such as the Kuokesale Fault Zone, the Dashixia Fault Zone, the Tuoshengan Fault (northwest of the epicentre), the Piqiang North Fault Zone, and the Wensu North Fault Zone situated in the southeast of the epicentre experienced stress accumulation and warranted attention. The co-seismic deformation field of the two strong aftershocks indicates a southeast-trending reverse fault located in the middle of the basin. This fault, influenced by the continuous compressive movement of the Maidan Fault, predominantly exhibited reverse movement during an earthquake. The seismic activity in the Wushi earthquake sequence indicates crustal shortening in the southern Tianshan region facilitated by the absorption of compression from the frontal compressional thrust belt and high-angle reverse faults in the orogenic belt.