Comparative Analysis of Triggers for Evacuation during Recent Tsunami Events

In the case of a near-field tsunami event, coastal residents must quickly become aware of the potential danger of a tsunami taking place and start taking actions to evacuate. The present paper aims to show which types of evacuation triggers worked amongst coastal residents with different characteristics and backgrounds by conducting a comparative analysis of four recent near-field tsunami events. The results of the analysis showed that basic knowledge about tsunamis had been spreading throughout the areas studied, which triggered many people to evacuate soon after feeling ground motion, almost regardless of how frequently each area had experienced tsunami events in the past. Educational activities and community-based efforts appear to be some of the reasons that can explain this finding. However, because some people in areas with fewer past experiences only evacuated after noticing last-minute signs and there is a nonnegligible number of visitors present in the coastline of certain communities, continuous efforts toward developing tsunami awareness are still needed. The results of the analysis also showed that in areas with fewer past experiences, people were more likely to wait for messages from the authorities to decide to evacuate. This finding highlights the importance of teaching local residents and visitors how a tsunami can reach a given area in a relatively short period of time.