[H-DS11] Geohazards in humid, tectonically active countries and their precursors

[HDS11-03] Preparation of geomorphological and geological data for earthquake-induced landslides potential assessment in Japanese Island situated in a humid, tectonically active volcanic zone

*Takehiko Suzuki¹, Masahiro Chigira² (1.Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, 2.Disaster Prevention Research Institute, Kyoto University)

Keywords:humid, tectonically active volcanic zone, earthquake-induced landslides, geomorphological and geological data, tephric loess

Japanese Island situated in a humid, tectonically active volcanic zone is geomorphologically characterized by frequent occurrence of landslides, resulting in severe disaters. So-called “loam” composed of primary fall-out tephras and tephric soil deposits (tephric loess) is one of the factors cause earthquake-induced landslide. To evaluate potential of slope failure by this combination in the Japanese Island, we are preparing GIS data set for conditions such as thickness distribution of loam shown in this study, landform classification by Ministry of Land, Infrastructure, Transport and Tourism and this study, and possibilities of strong earthquake predicted as the Probabilistic Seismic Hazard Map by National Research Institute for Earth Science and Disaster Resilience. Earthquake-induced landslides potential assessment will be examined on these overlaid maps, considering frequency of landslides in geological time. To estimate the frequency, we are examining unconformities within “loam” in several areas where thick loam has been formed such as the Izu-oshima Island, Tokyo.