Dynamic Rupture and Strong Ground-Motion Simulations of the 8 January 2022 Ms 6.9 Qinghai Menyuan Earthquake

Abstract

Abstract The 2022 Ms 6.9 Qinghai Menyuan, China, earthquake is the most destructive earthquake to have occurred near the Lenglongling fault at the western segment of the Qilian–Haiyuan fault since 2016 Ms 6.4 Menyuan earthquake. The 2022 earthquake generated surface rupture measuring about 30 km with an unexpected maximum offset larger than 2.6 m in the epicentral area, and severely damaged the local infrastructure and transportation. To analyze the possible causes of the large surface slip and to reveal the rupture process, we modeled the dynamic rupture and strong ground motion of the 2022 Menyuan earthquake using the curved-grid finite-difference method. In the simulation, the geometry of the fault is constructed based on the observed trace of the surface ruptures. The background tectonic stress field is assumed to be uniform, and the slip-weakening law with the constant friction coefficients is adopted. Our modeling results showed that the rupture model with a focal depth of 6 km and a rupture width of 10 km provides a good fit to the observed surface slips and the field records. We also investigated the effects of the focal depth and the rupture size on the surface slips. It is found that under the same conditions, the dynamic rupture models with a larger rupture size generated greater coseismic slips at the surface. However, only the model with a relatively smaller rupture width produced an Mw∼6.7 event similar to the Menyuan earthquake. In contrast, the influence of the focal depth is less significant. The decrease of the focal depth only leads to a slight increase in surface slip. Our results illustrated that a surface-breaking rupture with a relatively narrow width may physically control the general characteristics of the earthquake. This study provides a new insight into the rupture dynamics of the 2022 Menyuan earthquake.