How to Survive a Tsunami: An Individualistic Maxim in Japanese Collectivism

Many researchers interested in disaster risk reduction have focused on precise prediction, a rapid alert system, or substantial buildings. However, these rational devices often make us more vulnerable to natural disasters. It can be called “self-domestication of humans” (Obara 1989). Why do many people fail to escape from natural disasters? Why do many people hope to remain in the affected area? Why do many people have guilt feeling if they have the fortune to survive? The human mind in emergency is not so rational, but rather is emotional, social and moral. "The heart has its reasons of which reason knows nothing" (Pascal 1670). In emergency situation, our sociality and morality operate so strong that we often feel it very difficult to trade off our survival against them. For successful evacuation, we need to explore this intuitive heuristics of the human mind.

The Ministry of Land, Infrastructure, Transport and Tourism of Japan conducted the survey of evacuation behavior among the survivors of the 2011 tsunami (MLIT 2012, N=10,603). Based on this data, we will explore three characteristics of evacuation heuristics.

(1) Priority of intuitive judgement as a trigger of evacuation behavior to tsunami alert.

(2) Strong bystander effects occur after the M9 earthquake.

(3) Gathering information, protection of one’s family, and serving group mission are typical behavior to delay the time to start evacuation.

“Tsunami-Tendenko” (running to a higher ground by oneself, without finding family members) is known as an individualistic maxim of tsunami evacuation in northeast region (Katada 2014). Nominally, it inhibits us from helping our family members, but it maximizes the number of survivors by reducing the double contingency risk of deciding whether to help family members or not. In addition, the maxim emphasizes the preparedness against tsunami. Cooperation and trust must be prepared before tsunami, not during tsunami.