The 2011 Tohoku tsunami was 2 to 3 times higher than the existed expectations. Many people were unexpectedly attacked by this devastating tsunami. In this study, the authors focused on an elderly care facility in Minami-sanriku town, Miyagi Pref., Japan, which was located outside the expected inundation zone. 41 users per 69 were killed by this unexpected tsunami. This study finds out the reasons why 28 users could evacuate, using an evacuation simulation, interviews, and a tsunami simulation. As a result, it was clarified that the unexpected huge tsunami shortened the usable time for evacuation because of the drastically delayed start time of evacuation. Quickly wide-spreading sense of crisis, assembly places after shaking, and so on should be considered for a safer society, able to cope with unexpected large tsunami events.
