Evellyn Tan

Tsunami Bōsai: Building Coastal Resilience in South Izu Peninsula

Evellyn Tan

Advisor: Miho Mazereeuw Readers: Caitlin Mueller & Cristina Parreño

Bōsai is a Japanese term — "Bo" meaning prevention and "Sai" disaster — commonly associated with disaster preparedness and the necessary actions against such catastrophic events. In Japan, Bōsai is critically embedded in the Japanese culture, where locals can face disasters at any time. Therefore, embedding bōsai values into urban coastal landscapes with greater emphasis on the community's needs is vital in building the nation's social-ecological resilience.

Located in the Circum-Pacific of "Ring of Fire" and surrounded by sea, Japan, with an extreme range of topographic and geomorphological landscape, is highly prone to disasters. The south coastal belt of the islands is incredibly vulnerable to mega-tsunamis, as the country is situated at the collision plate forming active troughs capable of generating forcefully destructive tsunami waves. The Great East Japan Earthquake that hit the Tohoku region in 2011 exposed disaster planning challenges and a looming demographic crisis in Japanese coastal towns.

Despite the elaborate network of tsunami barriers constructed by the government to protect the coasts, many coastal settlements will still be significantly affected by Level 1 tsunamis of 10 meters or higher in the future. Thus, further building disaster-resilient capacity of social and ecological ecosystems against tsunamis is vital to the survival of lives and livelihoods along Japan's coast. This thesis highlights the importance of socio-ecological design strategies of coastal towns by re-evaluating and re-imagining current tsunami evacuation spaces. This thesis focuses on the southern tip of the Izu Peninsula region, which has been identified as highly vulnerable to tsunamis propagated by the Nankai Trough. The project critically interrogates current typologies of existing evacuation towers and public spaces operating solely for emergency use. It proposes an evacuation space that actively engages with the ecological environment and local communities to support coastal livelihood and economy on a daily basis on top of providing safer high ground and tsunami evacuation routes.

Image 1 (above): Tsunami Bosai Expanded Field Defined (Credit: Evellyn Tan). Image 2 (below): 2011 Great East Japan Earthquake, Miyagi Prefecture. (Credit Image 2: Kyodo AP).