Abstract This study systematically analyzes the tectonic mechanism and seismic background of the Wushi earthquake by employing double-difference earthquake location algorithm(DDELA) and the cut and paste(CAP) method, combined with geological structural information. The results reveal that the seismogenic fault is the Maidan Fault. Aftershocks on the SW side of the mainshock significantly outnumber those on the NE side, reflecting significant heterogeneity in the subsurface medium near the epicenter, causing regional compressive stress to be concentrated and released at the epicenter. The focal mechanism shows that the mainshock is dominated by reverse faulting with minor strike-slip, consistent with the mechanisms of historical regional earthquakes, suggesting relatively stable stress accumulation and rupture mechanisms in the area. Although the focal mechanisms of M ≥ 5 aftershocks are generally consistent, notable differences exist in nodal plane orientations and spatial distributions, indicating that this earthquake sequence was jointly controlled by a complex fault system comprising the Maidan Fault and its branch faults. This earthquake demonstrates that despite low activity in the past two decades, the Maidan Fault retains the capacity to generate strong earthquakes. It also highlights the critical roles of deep medium heterogeneity and fault complexity in the nucleation and occurrence of strong earthquakes.
Zhou et al. (2026) studied this question.