Advanced casualty estimation based on tsunami evacuation intended behavior: case study at Yuigahama Beach, Kamakura, Japan

Tsunamis are some of the most destructive types of natural hazards that can affect coastal areas. To optimize tsunami mitigation measures, it is important to estimate the potential casualties that can result from one of these events. Taking into account tsunami awareness and the possible evacuation behavior of at-risk individuals is necessary to estimate the number of casualties, though most of the research carried out to date has not considered detailed evacuation behavior when conducting simulations. In the present study, the authors proposed a new approach to estimating the number of tsunami casualties, based on a tsunami evacuation simulation model that considers the evacuation behavior of local residents, tourists and beach users. Such behavior parameters were incorporated by analyzing the results from previous questionnaires surveys. The model was applied to Yuigahama Beach in Kamakura City, Japan, with the aim of assessing potential tsunami casualties and providing suggestions regarding tsunami mitigation measures. The authors conducted seven tsunami inundation simulations for different earthquake scenarios, and then casualties were estimated considering six different evacuation scenarios. Based on the simulation results, it appears particularly important to attempt to improve the intended evacuation behavior of both the local population and visitors. Particularly, providing information about safe places and the routes to reach them is necessary, as prompt evacuation and heading to higher ground were found to be insufficient behavior to save lives during a tsunami event.