Coseismic and Pre-seismic Deformation Characteristics of the 2022 MS 6.9 Menyuan Earthquake, China

On January 8, 2022, the M-S 6.9 Menyuan earthquake occurred in Menyuan, Qinghai province, China; the epicenter was on the fault terrace of the Lenglongling and Tuolaishan faults. To investigate the coseismic and pre-seismic deformation associated with the event, we constructed physical models using interferometric synthetic aperture radar (InSAR) and global navigation satellite system (GNSS) data and inverted the fault slip distribution, fault coupling fraction, fault slip deficit and strain rate. The primary inversion results were as follows: (1) The InSAR coseismic deformation pattern indicates that the left-lateral strike-slip deformation occurred in the NW-SE direction, with the maximum relative displacement in the line-of-sight direction being 1.3 m. (2) The coseismic slip mainly occurred in a 30 x 25 km region at a depth of 0-8 km. The maximum fault slip was 3.81 m with a moment magnitude (M-W) of 6.6. (3) Based on the fault coupling inversion, the seismogenic fault was strongly locked (> 0.96) up to a depth of similar to 10 km before the Menyuan earthquake. The coseismic rupture zone in the fault strike direction was significantly smaller than the pre-seismic locked region. (4) The pre-seismic strain rates revealed NE-SW compressive and NW-SE tensile deformations, reflecting a considerable left-lateral strain accumulation in the seismogenic region, with a maximum shear strain rate of 2.6 x 10(-8)/year. Therefore, attention must be paid to the seismic hazards posed by the Tuolaishan and Lenglongling faults adjacent to the seismogenic region.