On 3 August 2014, an earthquake struck Ludian County, Yunnan Province, China, which has caused a large number of coseismic landslides. Visual interpretation permitted 284 and 1053 landslides before and after the event to be mapped, respectively. This work attempted to analyse these two kinds of landslides. Conditioning factors, such as slope angle, aspect, curvature, elevation, distance from drainages, intensity and lithology, and the index of Landslide Number Density (LND) were used to describe the spatial distribution of these landslides. Then, the pre-earthquake and coseismic landslide susceptibility maps were produced using the information value model. The areas under curve are 84.73 and 77.05%, for the pre-earthquake and coseismic landslides, respectively. The results show that the LND values as well as the information values of coseismic landslides are larger than those of the pre-earthquake case. This also indicates that this Ludian earthquake has a relatively larger ability to trigger landslides.

Debris flow is one of the most common natural hazards in the semiarid mountainous areas of the Southeast (SE) Tibetan Plateau. Because of unique geology, geomorphology, and diverse climate conditions, debris-flow susceptibility in the mountainous areas shows significant regionalism. In this study, an index entropy model is adapted for sensitivity analysis of the impact factors of debris flows in the semiarid areas, and the Benzilan-Changbo segment of the upper reaches of the Jinsha River are selected as an area of interest in a case study. Based on the sensitivity analysis, six factors, including, lithology, slope gradient, slope aspect, relative relief, catchment system geomorphologic entropy, monthly average precipitation (June–September), and normalized difference vegetation index (NDVI) are considered debris-flow susceptibility assessment factors. The results show that landform, lithology, and vegetation are the three most important factors affecting the susceptibility of the debris flow in se...