POTENTIAL SEISMIC RISK ASSESSMENT OF URBAN CITIES IN JAPAN CONSIDERING THEIR REGIONAL CHARACTERISTICS

摘要

In Japan, various schemes for seismic risk assessment have been developed and applied to numerous urban cities especially after the 1995 Hyogoken-Nambu Earthquake. In general, regional characteristics such as soil conditions, buildings conditions, open-space areas, fire-resistive building ratio, building-to-land ratio, etc. are mainly taken into account in the conventional seismic risk assessment from the micro point view, where the entire area concerned is divided into numerous unit areas. However, as the 1995 Hyogoken-Nambu Earthquake revealed, in order to assess the potential seismic risk involved in urban cities and to utilize them for the future earthquake preparedness measures in a rational way, it is essential to consider broad array of issues related to regional characteristics that had not been taken into account in the conventional seismic risk assessment. This study proposed a methodology to estimate potential seismic risk of urban cities based on their regional characteristics. Regional characteristics included macro information such as topography, climate, location of active faults, regionally dependent building types and their seismic capacity, experience of past earthquake disasters, background history of urban development, inter-city traffic system, accessibility from neighboring cities, etc. as well as micro information taken into account in the conventional seismic risk assessment. The methodology was applied to typical urban cities in Japan, and its applicability to assess the potential seismic risk was also discussed herein.