InSAR Coseismic Deformation, Fault Slip Inversion and Coulomb Stress Evolution of the Qinghai Menyuan Earthquake on January 8, 2022, China

Abstract

On January 8, 2022, an M6.9 earthquake occurred in Menyuan, Qinghai, which caused surface damage. In this paper, the line-of-sight (LOS) coseismic surface deformation field is obtained by the interferometric synthetic aperture radar (InSAR) of the Sentinel-1 satellite. Constrained by the InSAR surface deformation field, a Bayesian method based on sequential Monte Carlo sampling was used to invert the geometric parameters of seismogenic faults and the distribution of fault slip. Moment magnitude of the model is Mw6.6. The earthquake was determined to occur at a left-lateral strike-slip fault. Based on the historical strong earthquake dislocation model, the PSGRN/PSCMP program was used to calculate the Coulomb stress change at the epicenter of the 2022 Menyuan M6.9 earthquake caused by the surrounding historical strong earthquakes. The results show that the occurrence of the Gulang M8 earthquake in 1927, the Menyuan Mw5.7 in 1986 and the Menyuan Mw5.9 earthquake in 2016 caused a significant increase in Coulomb stress at the epicenter of the 2022 Menyuan earthquake. The coseismic and post-seismic Coulomb stress increases were greater than 0.01 MPa. Combined analysis of this result with regional tectonic stress, allows us to conclude that the 2022 Menyuan M6.9 earthquake occurred on the dynamic background of the continuous extrusion of the Indian plate towards the Eurasian plate, and the regional historical strong earthquake activity played a significant role in promoting it. The research results provide a theoretical basis for understanding the seismogenic background and dynamic mechanism of the 2022 Menyuan earthquake.