What Differentiated Local Casualties Caused by the Tsunami ?

Abstract

Generally, the impacts of a tsunami can be understood in terms of the corresponding relationships between hazard scale and extent of building damage and loss of human life. Focusing on community-scale statistics of the municipalities of Kamaishi, Kesen'numa, Minami-sanriku, and Yamamoto, which were severely affected by the 2011 Tohoku Earthquake, significant variations are observed in the mortality rates at affected villages that experienced the same levels of building damage. Moreover, differences in the geographical locations of the villages also impact their mortality rates. A village with a high mortality rate is situated either on a coastal plain or on an inland valley plain some distance from the sea, whereas a village with a low mortality rate is paradoxically in close proximity to the sea, often facing a small bay. Close interrelationships are identified among geographical conditions and possible evacuation activities, which relate to the geographical imaginations of inhabitants based on their inherent local knowledge and interactions with physical and built environments. Interviews with survivors indicate decisions to escape could not be made quickly after the earthquake occurred. Rather, people were confused regarding the occurrence and magnitude of the tsunami and the provision of evacuation sites. The tsunami waves were often different from those that were formally forecast and broadcast, which compelled people to act flexibly. Consequently, it is argued that it is necessary to emphasize the effects of local geographies on interactions between tsunami waves and evacuation activities from a grassroots perspective when preparing for future tsunamis.