| 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. First, we examined roles of bedrock geology and rock uplift rate on regional frequency of deep catastrophic landslides. According to these results, we had roughly classified Japan into four categories in terms of past deep catastrophic landslides frequency and published “Deep catastrophic landslide frequency map of Japan” Then, we propose a new method to estimate landslide susceptibilities for many small catchments (~1 km2) over relatively large areas (hundreds of square kilometres). 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 started the survey for clarification of potential sources of deep catastrophic landslide in high frequency region using this method. |
