Complex fault geometry and slip distribution of 2022 Mw 6.6 Menyuan, China, earthquake from joint inversion of GNSS and InSAR observations

Abstract

On January 7, 2022, a Mw 6.6 earthquake occurred in Menyuan County, Qinghai Province, China. To understand the coseismic deformation mechanism of this earthquake, we utilized GNSS and InSAR geodetic observations to obtain the coseismic deformation field and inverted for the slip distributions of different fault models. Through a comparative analysis of the coseismic slip distribution characteristics of different fault models and fitting degree of observations, we proposed the relatively optimal fault model. The coseismic deformation results of two types of observations consistently show a dominant horizontal strike-slip motion for this earthquake. The deformation characteristics of the coseismic LOS displacement profile model, considering the fault dip angle and slip amount, indicate that the coseismic slip is concentrated in the shallow portion, with a maximum slip of 3.29 m at a depth of 1.31 km. The inversion results of the optimal fault model proposed in this study indicate that compared to the surface trace of the Lenglongling fault, the surface trace of the eastern section of the primary fault is deflected by 9.28°, with a length of approximately 14 km, and the western section extends westward approximately 9 km along the Lenglongling fault. In the strike-change area between the Lenglongling fault and the Tuolaishan fault, the secondary fault connects the primary fault and extends westward along the Tuolaishan fault for approximately 8 km. The primary fault corresponds to the Lenglongling fault, with a maximum slip of 4.28 m, and the secondary fault corresponds to the Tuolaishan fault, with a maximum slip of 2.44 m.