Seismogenic fault model of the 2024 Mw 7.0 Wushi earthquake, western China, from geomorphology and aftershock relocation

The 23 January 2024 moment magnitude (Mw) 7.0 Wushi earthquake, the largest instrumentally recorded event in the SW Tian Shan of Xinjiang, western China, provides a rare opportunity to investigate the complex fault geometry within this active fold-and-thrust belt. Using high-resolution uncrewed aerial vehicle imagery, field investigation, remote sensing analysis, and relocation of the aftershock sequence, we study the seismogenic fault and associated structures. Surface cracks observed along the pre-existing fault scarp align with branches of the north and south Maidan fault, suggesting that both fault segments accommodated seismic energy during the mainshock. Analysis of pre- and post-earthquake satellite imagery reveals an ENE-trending, ∼4-km-long co-seismic surface rupture produced by the Mw 5.7 aftershock on 30 January, exhibiting a maximum vertical displacement of at least ∼1.3 m. Aftershock relocations of 4738 events within 40 days define a NE-SW−trending seismic zone extending over ∼70 km at depths <25 km. Focal depth distributions and surface rupture characteristics further indicate the activation of two south-dipping back-thrusts, reflecting the out-of-sequence thrusting of the Maidan fault system. These back-thrusts, along with the northern and southern branches of the Maidan fault, form two distinct pop-up structures. Given the irregular earthquake recurrence intervals and out-of-sequence faulting in the SW Tian Shan, additional investigations are essential for refining regional seismic hazard assessments.