Seismic Risk Assessment for Tokyo Bay Region by Geographic Information System

坂神淡路地震（1995年）表明，在高度城市化地区，个别地震灾害现象的复杂相互作用可能对整个地区的灾害产生强烈的整体影响。因此，我们提出了“区域活力”指数的概念来评估地震风险潜力。这是一个从两个角度预测地震灾害和灾害程度的评价指标，一个是对每个评价单元的微观评价，另一个是对整个区域的宏观评价。然后，考虑到从全国人口普查、商业统计等数据中得出的各种区域特征，按潜力评估损害对区域的相互影响。首先，提出了三大指标之一的“经济活力”指标的概念和方法，作为区域活力评价的主要常规。该指标是通过比较正常情况下的经济活力和受灾情况下的经济活力降低来评价故障程度的指标。此外，还对坂神湾地区进行了坂神淡路地震灾害风险分析的案例研究。其次，在此基础上，验证了经济活力评价方法在日本其他地区的普遍适用性。特别是，我们建议对东京湾地区进行地震危险性评估。具体来说，我们要说明的是，地震发生时，经济活力指数从正常水平下降的可能性大小，可以用来评估地震风险。最后，将本文的地震危险性评价指标与东京大都会早期采用常规评价方法所作的类似评价指标进行了比较，证明了本文的评价指标的独特有效性。

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.