Probabilistic tsunami risk assessment based on submarine active faults and their possible interactions in the sea of Japan

Abstract The Sea of Japan coastal areas have experienced tsunami damage caused by submarine active seismic faults. Large uncertainties remain regarding seismic activity of these faults and the following tsunami. Probabilistic tsunami risk assessment (PTRA) enables the evaluation of tsunami risk accounting for such uncertainties. In this study, the tsunami risks of a thermal power plant located in Joetsu on the Sea of Japan coast were evaluated using PTRA based on submarine active faults, including coupled faults, across the Sea of Japan. The results indicate that coupled fault models had large impacts on risk levels, especially for severe damage states. For the most severe damage state, the median expected annual probability of experiencing this damage state among the structures increased by 154% when coupled fault models were considered. In addition, the risk levels varied depending on the structures, even within the same site. The spatial distribution of tsunami risk revealed that structures with high risk levels existed not only along the coast but also inland. The findings of this study provide practical insights into reliable tsunami risk assessment, which are useful for the development of disaster resilience measures, especially for infrastructure.