Hazard Map for Slope Instability in Japan

Some Considerations and Proposals

Abstract

Japan has many steep slopes, and a variety of slope movements (landslides) occur in many places every year. These movements are triggered by heavy rain falls, earthquakes and volcanic activities. As a result, serious disasters with human suffering have occurred. It is difficult to predict the occurrence of such slope movements, and also to prevent or mitigate their hazards.
Except for some active volcanoes, Japan has few hazard maps for slope movement. This results from such problems of drawing hazard maps as: 1) technical problems for evaluation of slope instability
2) areas susceptible to debris derived from slope movements
3) adjustment of a variety of source data
4) use of digital data for GIS
5) method of presentation and publication of detailed information regarding hazards from a slope movement
This paper discusses the importance and contents of hazard maps. Its fundamental studies including analysis of past disaster records, construction of hazard prevention or mitigation system with the cooperation of local governments, research institutes, engineering agencies and inhabitants. We also propose the need to include education and examination for disaster prevention. In 2001, a new law on hazards resulting from slope instability will be enforced. As this law requests a hazard map on slope instability, many useful hazard maps will be published in the near future.
We show hazard maps on volcanic activity, which are the most excellent ones in Japan, and discuss prediction of volcanic eruption, analysis of volcanic activity, kinds of disaster, analysis of data based on past disasters, method of drawing a hazard map, and the estimation of scenarios of disasters.