Spatial distribution of landslide shape induced by Luding Ms 6.8 earthquake, Sichuan, China: case study of the Moxi Town

Landslides induced by the 2022 Luding Ms 6.8 earthquake mainly occurred in the Moxi Town, the Detuo Town, and the Wanggangping County, causing serious casualties and property losses. Among these places, the Moxi Town is the nearest one to the earthquake epicenter, where the landslides triggered by the Luding earthquake are not huge but with distinctly different shapes. Based on field investigation, the shapes of landslides are identified and can be categorized into 9 types (e.g., wide shape, strip, vertical rectangle, horizontal rectangle, water drop, fan, Y shape, sporadic, and knife shape), which are influenced mainly by 8 influencing factors, including land use type, lithology, slope, slope style, aspect, elevation, starting position, and watershed evolution index. According to the statistical analysis results, lithology could be the main factor causing the different shapes of landslides. Landslides with the wide shape are more likely to occur in the looser gravel layer. The long and narrow landslides with the strip shape are more likely to occur in the granite formation, the moving direction of which is affected mainly by fractures in the rock mass. In the same lithology, the shapes of landslides are affected mainly by the slope, the elevation, and the original position. The distribution characteristics of different landslide shapes could be used to investigate the influences of the local terrain, lithology, and other factors. At the same time, landslide shapes can reflect the landslide evolution, which provides essential support on the emergency response and risk mitigation.