Differences in factors determining landslide hazards among three types of landslides in Japan

The motivation for this study was to clarify the factors that affect landslide occurrences at the national level in Japan and differences in the factors that result from landslide types. The factors that cause differences in the number of rainfall-triggered landslide disasters in 47 Japanese prefectures were examined using generalized linear models. The analysis was conducted for each of the three types (i.e., steep-slope failure, deep-seated landslide, and debris flow) of landslide disasters. For all types, the rainfall index and the number of landslide-prone areas were selected with positive coefficients while the accretionary complexes geological type was selected with negative coefficients. For steep-slope failure, forests and land for buildings were selected with negative and positive coefficients, respectively. For deep-seated landslide and debris flow, land use was seldom selected. Thus, the factors were found to have differed as a result of the landslide type. Because the number of landslides alters the fatalities and building damage in Japan, this study contributes to the prioritization of landslide countermeasures at the national level.