Seismogenic structure and rupture characteristics of the 2023 M_S4.9 xingwen Earthquake in Sichuan (China)

On May 4, 2023, an M_S4.9 earthquake struck Xingwen, Sichuan, China. Although moderate in magnitude, the event posed a potential threat to residents and nearby shale gas production. However, the seismogenic fault and rupture characteristics remain unclear. Here, we used interferometric synthetic aperture radar (InSAR) observations and seismological data to determine the source fault. Eighteen Sentinel-1A synthetic aperture radar (SAR) images from two ascending orbits were processed using the differential-InSAR technique, with noise reduction performed through multi-interferogram stacking. The derived co-seismic deformation field indicates a thrust-dominated rupture with a maximum line-of-sight displacement of approximately 3 cm. Using a combination of multi-start adaptive Gauss–Newton nonlinear and bounded least-squares linear inversions, we resolved the fault geometry and slip distribution. Together with aftershock analysis via the principal component analysis method, the seismogenic fault was identified as an east-dipping blind thrust fault (strike 345°, dip 23.3°), with slip concentrated at depths of 2–4 km, a released seismic moment of 4.38 × 10¹⁶ N·m (M_W5.0), and a shear modulus of 24.3. This study clarified the rupture characteristics of the Xingwen earthquake, highlighting the value of integrating geodetic and seismological methods for fault identification and seismic risk assessment in shale gas regions.