Objectives On January 8th 2022, an Ms 6.9 earthquake struck Menyuan, Qinghai Province, China. The epicenter is located in the middle section of Qilian-Haiyuan fault in the northeast margin of the Tibetan Plateau, which is a seismic gap. It is of great significance to study this earthquake for understanding the tectonic deformation mechanism, strain release process and seismic hazards of the NE Tibetan Plateau.
Methods Differential synthetic aperture radar interferometry (D-InSAR) is used to obtain the coseismic deformation along the line of sight (LOS) of the Menyuan earthquake from Sentinel-1 satellite images. The co-registration of optically sensed images and correlation are used to obtain the EW coseismic deformation from the multi-temporal Sentinel-2 data. Based on the coseismic deformation field derived from InSAR interferograms, we invert the slip distribution.
Results The LOS deformation fields showed that the Menyuan earthquake caused a surface rupture of about 20 km long and the maximum LOS displacement was 0.75 m. The maximum EW displacement derived from optical images was 2.5 m. The slip distribution model showed that the Menyuan earthquake was dominated by a sinistral strike-slip. The coseismic slip is concentrated at a depth of 0-10 km. The maximum slip was 3.25 m at a depth of 4.89 km and the rake angle was 10.44°. The estimated total seismic moment is 1.07×1019 N·m, corresponding to a magnitude of Mw 6.6.
Conclusions According to the results from aftershock relocation, field investigation and tectonic background, we infer that the seismogenic fault is the Lenglongling fault and the eastern segment of Tuolaishan fault is also ruptured. The stress on the eastern segment of the Lenglongling fault and the western segment of the Tuolaishan fault is enhanced, implying that there is the possibility of strong earthquakes in this region in the future.