Seismic Risk Assessment for Tokyo Bay Region by Geographic Information System

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The Hanshin-Awaji Earthquake Disaster (1995) indicates that in a highly urbanized region, the complicated interaction of individual earthquake damage phenomena may have a strong overall impact on the region-wide damage. So we propose the concept of an "Regional Vitality" index in evaluating earthquake risk potential. This is an evaluation index with which to forecast earthquake damage and trouble degree from two viewpoints, one for a micro evaluation for each evaluation unit, and the other for a region-wide macro evaluation. We then evaluate the interaction effects of damage on the region by potential, taking into account various regional characteristics derived from the national census, business statistics and so on.First, we propose to show the concept and method of one of the three indexes "Economic Vitality" index as the main routine of Regional Vitality evaluation. This index is designed to evaluate the degree of trouble by comparing the economic vitality in an ordinary circumstance and the lowered one in a disaster-stricken circumstance. We also make a case study regarding the seismic risk analysis of damage in the Hanshin-Awaji Earthquake for the Hanshin Bay region.Secondly, we try to build on the outcome of the preceding one and verify the general validity of the Economic Vitality evaluation method for other regions in Japan as well. In particular, we propose to make a seismic risk assessment for the Tokyo Bay region pursttant to the evaluation method. Specifically, we intend to show that we can evaluate a seismic risk by sizing up a possible decline in the Economic Vitality index from the normal level when an earthquake strikes. We finally try to compare our own seismic risk assessment with an earlier similar assessment made by Tokyo Metropolis pursuant to a conventional evaluation method, thereby testifying to the unique effectiveness of the evaluation index of ours.