Analysis of Optimal Scale of Tsunami Protection Facility and Associated Residual Risk

Abstract

It is necessary to identify the role and limitation of a tsunami protection facility in installing the hardware elements and performing damage-reduction activities necessary to mitigate aftermath of the calamity. This paper examines the probabilities of occurrence of earthquakes of various magnitudes based on the earthquake occurrence frequency, estimates the corresponding tsunami damage, and proposes a method to determine the expected damage reduction, B(H), and expected damage, D(H), when a tsunami protection facility of a given scale, H, is built. With the goal of facilitating an agreement with the local government regarding the scale of the tsunami protection facility, promoting damage reduction measures, and reducing the overall social cost, it also proposes a scheme built on the results of the aforementioned method and the cost, C(H). The present method can also be used to identify residual risks, which will allow concerned parties to set concrete damage reduction targets.