CHARACTERISTICS AND SPATIAL DISTRIBUTION PATTERN OF M_S6.8 LUDING EARTHQUAKE OCCURRED ON SEPTEMBER 5, 2022

A M_S6.8 earthquake struck Luding County,Ganzi Tibetan Autonomous Prefecture,Sichuan Province,China on September 5,2022. The earthquake triggered large amounts of geological hazards,such as landslides,rockfalls,and debris flows,and caused severe fatalities and infrastructure damages. Utilizing the recently developed near real-time prediction model,we rapidly predicted the spatial distribution probability of the coseismic landslides in the region within two hours after the earthquake. Meanwhile,based on the high-resolution imagery from the Unmanned Aerial Vehicles(UAVs) and the Gaofen-6 Satellite,we interpreted a total of 3,633 coseismic landslides in the region with an area of 13.78 km². We then validated the results based on the field investigation. The results indicate that the coseismic landslides induced by the Luding earthquake are smaller than those triggered by the 2008 Wenchuan earthquake and the 2017 Jiuzhaigou earthquake. The coseismic landslides,which show a banded distribution pattern,mainly located on the sides of the Xianshuihe fault zone and the Dadu River and concentrate in the areas with a shaking intensity of Ⅸ degrees,such as Moxi Town,Detuo Town,and Wanggangping Town. We further analyzed nine controlling factors of the coseismic landslides,such as topography,lithology,ground motion parameters,et al. We find that landslides mainly occurred in the regions with an elevation range of 1000~1800 m and a slope range of 35°~55°. Most coseismic landslides are distributed within 1 km of the fault zone and in the granite formation,which highlights the strong impact of the fault zone. This study's results provide essential support to emergency response and risk mitigation.