Complex fault structures in the southern Tianshan revealed by the 2024 Wushi MS 7.1 earthquake sequence, China

On 23 January 2024, an MS 7.1 earthquake struck the Maidan fault (MDF) near Wushi County, China, located at the junction of the southern Tianshan and Tarim Basin, the largest recorded earthquake on this fault within the past century. To date, the detailed fault structure remains poorly understood due to sparse station coverage. We applied machine learning−based techniques to construct a high-precision earthquake catalog for the Wushi earthquake sequence, covering the period from 13 January 2024 to 1 March 2024. The resulting catalog comprises 17,021 earthquakes; ∼2.4× the size of the routine catalog reported by the China Earthquake Networks Center (CENC; https://www.cenc.ac.cn/). We further determine focal mechanisms for 33 events (ML ≥ 2.55) using waveform-based inversion methods, revealing that ∼75% of earthquakes exhibit reverse faulting characteristics. Stress field inversion based on these focal mechanisms indicates a regional stress regime of nearly horizontal north-south convergence and vertical extension. Spatial and kinematic analysis of the aftershock sequence reveals a complex fault system, composed of multiple secondary reverse and strike-slip faults with varying geometries, that is situated within the transitional zone between the MDF and the Wushi Basin and includes two southward-dipping imbricate fan structures that likely form a triangular zone with the northward-dipping main MDF. Our observations highlight the geometric complexity of the fault system in this region and its coordinated geomechanical expression of regional strain accumulation and release.