Regional scale rainfall- and earthquake-triggered landslide susceptibility assessment in Wudu County, China

Wudu County in northwestern China frequently experiences large-scale landslide events. High-magnitude earthquakes and heavy rainfall events are the major triggering factors in the region. The aim of this research is to compare and combine landslide susceptibility assessments of rainfall-triggered and earthquake-triggered landslide events in the study area using Geographical Information System (GIS) and a logistic regression model. Two separate susceptibility maps were produced using inventories reflecting single landslide-triggering events, i.e., earthquakes and heavy rain storms. Two groups of landslides were utilized: one group containing all landslides triggered by extreme rainfall events between 1995 and 2003 and the other group containing slope failures caused by the 2008 Wenchuan earthquake. Subsequently, the individual maps were combined to illustrate the locations of maximum landslide probability. The use of the resulting three landslide susceptibility maps for landslide forecasting, spatial planning and for developing emergency response actions are discussed. The combined susceptibility map illustrates the total landslide susceptibility in the study area.