ASSESSMENT METHOD OF ANNUAL RISK BY STORM SURGE DISASTERS IN JAPANESE MAJOR BAYS

Abstract

 Companies damaged by natural disasters can receive the insurance payout if they have contract in advance. Then, they can start recovery work in the early stage with budget and can minimize the losses due to interruption of business activities. On the other hand, number of examples in coastal disasters especially storm surge disaster is limited, and a few studies on probabilistic risk assessment have been done. Therefore, it is currently difficult for property and casualty insurance companies to estimate the amount of insurance payout to contracted companies. Settlement of accounts in the business year and insurance contracts are basically every year, it is also important to estimate annual expected damage. This study assesses annual aggregate risk of storm surge by typhoons which attack Japanese major bays by employing synthetic typhoon datasets made by the stochastic typhoon model. Storm surges are calculated by an empirical formula and a nonlinear shallow water equation model. This study estimates loss function by using the results of inundation simulation, and calculates damage using asset map. Risk curves from 1 area to 5 areas are estimated by the relationship of annual exceedance probability and annual aggregate loss. Annual expected loss are calculated by risk curves. It was shown that proposed risk curves enable us to perform more appropriate assessment close to the actual situation by conducting an annual aggregate risk assessment in an arbitrary region.