The 2022 Mw 6.6 Menyuan Earthquake in the Northwest Margin of Tibet: Geodetic and Seismic Evidence of the Fault Structure and Slip Behavior of the Qilian–Haiyuan Strike-Slip Fault

Abstract

AbstractOn 8 January 2022, an Mw 6.6 earthquake occurred along the Lenglongling fault (LLLF) (Menyuan, Qinghai Province, China), in the northeast margin of the Tibetan plateau. Here, we use imaging geodesy observations from pixel-offset tracking (POT) and Interferometric Synthetic Aperture Radar (InSAR) to quantify the coseismic displacement features and then combine InSAR and teleseismic velocity waveforms to constrain a finite-fault model to examine the kinematic slip behavior of the LLLF. We observe maximum displacements of >50 cm in the line-of-sight InSAR observations and >1 m in the east–west POT observations. Our preferred uniform-slip model indicates that the causative fault of this 2022 event ruptured the middle segment of the Qilian–Haiyuan fault (i.e., the LLLF) with a strike of 108.0°, a dip angle of 83.6°, and slip concentrated within a 15×8 km2 area and reaching a maximum value of 4 m. The total scalar seismic moment was 1.24×1019 N·m, and ∼67% of the energy was released in the first 6 s. We speculate that the 2022 event was controlled by complex fault geometries and slip partitioning, thus raising potential seismic risks associated with the outward extrusion of the plateau.