Classified surface rupture characteristics and damage analysis of the 2022 M_S6.9 Menyuan earthquake，Qinghai

At 01:45 on January 8, 2022, a M_S6.9 earthquake occurred in Menyuan County, Haibei Tibetan Autonomous Prefecture, Qinghai Province. The epicenter was located at （37.77°N, 101.26°E） in Lenglongling area of the central Qilian mountains, with a focal depth of 10 km. According to the comprehensive results of field investigation and aerial image interpretation by unmanned aerial vehicle （UAV）, the seismogenic fault of this earthquake undertakes a sinistral strike-slip motion, with a slight thrust component. The surface rupture zone of this earthquake is composed of the north main rupture zone located at the west end of Lenglongling fault and the southwest secondary traction rupture zone located at the east end of Tuolaishan fault. A series of extensional step-overs, sinistral displacements, tensional fractures, compressed bulges, and compressed ridges were formed along the surface rupture zone, resulting in damage to the Lanzhou-Ürümqi high-speed railway tunnels and bridges and the suspension of train services. In order to comprehensively analyze the different types of surface fracture features and seismic damage caused by this earthquake, field investigations and aerial interpretation using UAV were conducted along the rupture zone. As a result, typical coseismic surface fracture features along the rupture zone were categorized as follows: ① Various typical geometric structures, including echelon secondary rupture, sinistral extensional step-overs, sinistral compressed step-overs, dendritic and netlike forked rupture, etc; ② Horizontal displacement observed in various geomorphic markers, such as left-lateral dislocations in pastoral areas, truck trace, animal footprints, and gullies and gully ice; ③ Various types of vertical rupture, such as thrust seismic scarps and normal seismic scarps; ④ Various types of compressed rupture, such as compressed ridges and compressed bulges; ⑤ Different types of tensional crack zones, including pure tensional cracks and tensional-shear cracks. The geological and engineering seismic damage caused by the earthquake can be summarized as follows: ① Slope instability across the earthquake fault zone; ② Damage to highways, bridges, and tunnels across the earthquake fault zone; ③ Seismic deformation such as ice bulges and highway cracks in the areas near the earthquake fault zone. In addition, with the analysis and discussion on the distribution characteristics and formation mechanisms of the phenomena above mentioned, we should emphasize the importance of strengthening engineering anti-rupture fortification when engineering constructions cross active faults.