Coseismic slip distribution and 3D deformation field simulation of the Menyuan Mw 6.7 earthquake in Qinghai based on InSAR constraint

Abstract

On January 8, 2022, a Mw 6.7 earthquake stuck Menyuan Hui Autonomous County, Qinghai Province, resulting in extensive surface ruptures and the closure of the Lanzhou-Xinjiang high-speed railway. Objective This study aims to investigate the focal mechanism of the Menyuan earthquake. Methods D-InSAR technology was employed to process ascending and descending SAR data from Sentinel-1A, producing a coseismic deformation field. Using InSAR LOS deformation as a constraint, a two-step inversion method was applied to determine the geometric parameters of the earthquake fault and the detailed coseismic slip distribution. Additionally, the coseismic static Coulomb stress changes were calculated, and the seismogenic structure, along with the regional seismic hazard, was further analyzed. Results The findings reveal that the long axis of the InSAR coseismic deformation field is oriented WNW-ESE, indicating left-lateral strike-slip movement. The refined double-fault slip distribution shows that both the Lenlongling and Tuolaishan rupture segments exhibit high-inclination left-lateral strike-slip motion. To better understand the seismic deformation patterns, this study employs anelastic dislocation model and a viscoelastic half-space layered medium model to simulate the three-dimensional coseismic surface deformation, incorporating more accurate three-dimensional deformation from crustal layered models. The coseismic Coulomb stress changes suggest an earthquake risk at the western end of the Tuolaishan fault, the eastern end of the Lenlongling fault, and near the Daliang tunnel of the Lanzhou-Xinjiang high-speed railway, indicating a heightened potential for future rupture. Conclusion The research results can provide a reference for enhanced understanding of the three-dimensional crustal deformations associated with the Menyuan earthquake and the related seismic research.

Keywords

• menyuan mw 6.7 earthquake in qinghai
• fault slip distribution
• 3d coseismic deformation field
• static coulomb stress change
• lanzhou-xinjiang high-speed railway
• insar