Mortality rates caused by tsunamis vary from community to community, depending on geographical and social features peculiar to each. If the relation between mortality rate on the one hand and geographical and social features on the other can be quantitatively formulated, it can be a means to concretely evaluate the community's vulnerability with regard to evacuation (hereafter, evacuation vulnerability) and to adopt measures that effectively reduce loss of human life.
Therefore, the authors proposed to apply HVI (Human Vulnerability Index), defined as the rate of mortality divided by the rate of incidence of washed-out buildings, to evaluate the evacuation vulnerability of a municipality. Then, using reliable public databases, the authors evaluated the HVIs of the twenty municipalities that were heavily damaged by the tsunami of the 2011 Great East Japan Earthquake. And, they applied a multiple-regression analysis using the following four factors as explanatory variables and extracted a reliable formula (R=0.908), which enables us to analyze the evacuation vulnerability more rigorously. The formula also enables us to evaluate the HVI of a municipality before being suffered with a large tsunami.
1) Allowance: Tsunami arrival time after earthquake divided by length of evacuation route;
The increase of allowance effectively lowered HVI.
2) Preparedness: Rate of persons who always prepared emergency bag;
Disaster education such as letting people prepare emergency bags was effective in lowering HVI.
3) Road serviceability: Rate of car evacuees multiplied by car speed;
The higher the road serviceability, the lower the HVI.
4) Warning intensity and cognition: Forecasted tsunami heights multiplied by people’s cognition rate;
The forecast tsunami heights initially broadcast to the municipalities' areas was sensitive to HVI.
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