Shapes and Mechanisms of Large-Scale Landslides in Japan: Forecasting Analysis from an Inventory (WCoE 2014–2017)

Abstract

Large-scale landslides with widths and lengths of 1 km or more have been reported in many parts of the world. Occurrences of large-scale landslides have recently tended to increase due to climate change and frequent seismic activity. To conduct research on proper measures for large-scale landslides, elucidation of the occurrence mechanism, for which there are as yet many unclear points, will be required in future. The Japan Landslide Society established a research committee that worked from 2011 to 2014 to elucidate the occurrence mechanisms of large-scale landslides. Analysis of examples of large-scale landslides collected from members of the research committee showed that a volume of moving body larger than 1 × 106 m3 and a maximum landslide thickness of more than 30 m are appropriate as the definition of a large-scale landslide. The shape of a large-scale landslide depends on the geology and age of the landslide site, and landslide activity and history affect the symmetry of the shape of a landslide. This paper presents some results of the WCOE (2014–2017) project titled “Emergency response support system for large-scale landslide disasters” by the Japan Landslide Society.