Coseismic deformation and slip model of the 2024 MW7.0 Wushi earthquake obtained from InSAR observation

Abstract

On January 23, 2024, an MW7.0 earthquake occurred in Wushi County. This earthquake was the largest earthquake event in the south Tianshan Fault Zone in the past century. In order to determine the seismogenic structure of the Wushi earthquake and analyze the regional tectonic stress characteristics, we obtained the coseismic deformation field using radar interferometry and pixel offset based on Sentinel-1A data, and estimated the optimal fault geometric parameters applying the Bayesian nonlinear inversion. The results show that the maximum ascending line-of-sight uplift displacement is ~80 cm, and the maximum line-of-sight subsidence is ~16 cm. The line-of-sight coseismic deformation and pixel offsets indicate the significant vertical deformation characteristics of the Wushi earthquake, while the reverse pixel offset results in the azimuth direction of the ascending and descending orbit indicate obvious left-lateral strike-slip on the seismogenic fault. The inversion results show that the seismogenic fault of the Wushi earthquake is SW trending, NW dipping, with an optimal fault dip angle of ~67° and an average rake angle of ~60°, indicating that the coseismic slip is mainly driven by thrust-slip motion with a minor left-lateral strike-slip component. The deformation pattern and fault geometry parameters of the Wushi earthquake are consistent with the kinematics and geometry of the Maidan-Shayilamu fault at the basin-mountain boundary in the southern margin of the Tianshan Mountains. The high dip angle fault with strike- and thrust-slip activity of the Wushi earthquake indicates oblique convergence between the southern Tianshan Mountains and the Tarim Basin, and emphasizes that crustal shortening in the Tianshan region is absorbed by the nascent thrust nappe belts in the piedmont areas and the reverse faults with high dip angles in the orogenic regions.

Keywords

• wushi earthquake
• coseismic deformation
• coseismic slip distribution
• thrust nappe