Tsunami Evacuation: Lessons from the Great East Japan Earthquake and Tsunami of March 11th 2011

This report presents a comprehensive analysis of tsunami evacuation practices based on experiences during the Great East Japan earthquake and tsunami of March 11th, 2011. The study focuses on the regions of Tōhoku, Washington, and New Zealand, which face local earthquake and tsunami risks from subduction zones. Key findings indicate a 96% survival rate in inundated areas, attributed to effective education and evacuation procedures such as school programs, hazard maps, and community involvement in evacuation planning. However, shortcomings were noted in the consistency of hazard and evacuation maps, which often underestimated worst-case scenarios, and the impact of sea walls on natural warning observation and evacuation behavior.

Furthermore, the report highlights the role of natural warnings, such as prolonged ground shaking, in triggering evacuations, emphasizing the importance of community awareness and immediate self-evacuation practices. While early warning systems are considered essential for enhancing resilience, the study suggests that overreliance on official warnings may delay evacuation efforts, as seen in Tōhoku due to previous false alarms leading to complacency. Recommendations include promoting community engagement in evacuation planning, improving the consistency and accuracy of hazard maps, and fostering a culture of immediate self-evacuation based on natural warnings to mitigate unnecessary casualties during tsunamis.

The study also underscores the significance of community ownership of disaster planning and the positive impact of community involvement in tsunami preparedness, as evidenced by the high survival rate in municipalities with well-developed engagement strategies. By drawing parallels between the experiences in Tōhoku and the potential risks faced by regions like Washington and New Zealand, the report offers valuable insights for further development of tsunami mitigation activities, emphasizing the need for continuous education, awareness, and proactive evacuation measures to enhance overall resilience in tsunami-prone areas.