A New Method for Assessing Deep Catastrophic Landslide Susceptibility

Abstract

3 Disaster Prevention and Mitigation Engineering Office (Tokyo, 1740065, Japan) 4 Unzen Restoration Work Office, Kyushu Regional Beaurou, Ministry of Land, Infrastructure, Transport and Tourism (Shimabara, Nagasaki, 8560866, Japan) In steep mountainous regions, deep catastrophic landslides that involve weathered bedrock as well as soils can cause serious damage. However, there is currently no widely used method for estimating spatial patterns of susceptibility to deep catastrophic landslides. We propose a new method to estimate landslide susceptibilities for many small catchments (~1 km 2) over relatively large areas (hundreds of square kilometers). Our method identifies catchments prone to deep catastrophic landslides according to three criteria: (1) catchments with ancient deep catastrophic landslide scars, (2) catchments with faults and landforms caused by long-lasting mass movements, and (3) catchments with many steep slopes that have large upslope contributing areas. We demonstrated the applicability of this method using data from Mount Wanitsuka, Miyazaki Prefecture, Japan, where deep catastrophic landslides occurred during a typhoon in 2005.