Topographic Controls on the Distribution of Coseismic Landslides: A Case Study Using the Coefficient of Variation of the 2014 Ludian, Yunnan, China, Ms6.5 Earthquake

Identifying the locations of potential landslide areas is fundamental for disaster prevention and mitigation. Considering the close relationship between landslides and geomorphic evolution, a new approach is proposed to predict which areas are prone to landslides based on the analysis of topographic features in the area affected by the 2014 Ludian, Yunnan, China, Ms6.5 earthquake. In our method, the expected slope angle (ES), which is related to the local relief in a grid cell, is defined to describe the terrain features within grid cells. Based on the relationship between the expected slope angle and the average slope, the cells in the study region can be classified into 3 different terrains. Our study shows that large landslides triggered by the Ludian earthquake are prone to occur in regions where the expected slope angle and average slope angle show obvious differences, which means that the region has sharp changes in relief and slope. In comparison with the coseismic landslides triggered by the 2017 Jiuzhaigou, Sichuan, China, Ms7.0 earthquakes, preliminary analyses infer that the distribution of coseismic landslides follows the general mass transportation features of a special region and that their occurrences are the kind of simultaneous adjustment of excess geomorphicity of hill slopes to a steady state.