The 8 January 2022, Menyuan Earthquake in Qinghai, China: A Representative Event in the Qilian-Haiyuan Fault Zone Observed Using Sentinel-1 SAR Images

Abstract

On 8 January 2022, a Ms 6.9 earthquake occurred in Menyuan, Qinghai, China. This event provided important geodetic data before and after the earthquake, facilitating the investigation of the slip balance along the seismogenic faults to understand seismogenic behavior and assess seismic risk. In this study, we obtained the interseismic (2016–2021) and coseismic deformation fields of the 2022 earthquake using Sentinel-1 synthetic aperture radar (SAR) images and estimated the slip rate, fault locking, and coseismic slip of the seismogenic faults. The results indicated that the seismogenic fault of the 2022 Menyuan earthquake, i.e., the Tuolaishan–Lenglongling Fault, had shallow locked areas before the earthquake; its long-term slip rate could reach 6 ± 1.2 mm/yr. The earthquake ruptured a sinistral strike-slip fault with a high dip angle; the maximum slip magnitude reached 3.47 m, with a moment magnitude of 6.6. The area of coseismic slip > 1.5 m was equivalent to the range of the isoline, with a locking value of 0.6. The interseismic locking region can limit the approximate scope of the coseismic slip distribution. The 2022 Menyuan earthquake released energy that had accumulated over 482 years in the stepover region between the Lenglongling and Tuolaishan faults. The accumulated elastic strain power of the Tuolaishan Fault was equivalent to an Mw 6.79 earthquake. These circumstances in terms of the strain energy balance demonstrate that interseismic locking, as constrained from the geodetic data, and the elapsed time from the previous paleoseismic event are useful for earthquake location and energy predictions.