Tsunami Casualty Risk Assessment Integrating Evacuation Tower Placement, Seismic Road Network Performance Enhancement, and Disaster Education

ABSTRACT Since the 2011 Great East Japan earthquake, tsunami evacuation towers have been constructed in coastal regions based on worst‐case predictions to provide additional safety margins against unprecedented tsunamis. However, the extent to which such assumptions effectively reduce casualty risk remains unclear. This study proposes a comprehensive risk‐based framework for estimating tsunami casualty risk, incorporating uncertainties associated with seismic and tsunami hazard intensities, structural vulnerabilities, and evacuation behaviors. The risk assessment focuses on the probability of evacuation failure, accounting for the loss of road network functionality due to seismic impacts and variations in evacuation behavior shaped by the conflicting influence of congestion and disaster education. Ground motion‐induced damage to road networks prior to tsunami arrival may delay evacuations, potentially leading to casualty rates exceeding initial estimates. Conversely, disaster education can facilitate earlier evacuations in response to seismic shaking, thereby increasing survival rates. As an illustrative example, the proposed framework is applied to a coastal region projected to be significantly affected by the anticipated Nankai Trough earthquake. Furthermore, this study evaluates the appropriateness of incorporating worst‐case scenarios in decisions concerning the placement of tsunami evacuation towers.