Tsunami evacuation: Lessons from the Great East Japan earthquake ...

2012
hazard through numerical modelling, which resulted in complacency and delays in
evacuation on March 11 th 2011 despite the natural warnings. The issues caused by lack of
experience of local tsunami are likely to also affect Washington and New Zealand for the
same reasons, where emergency officials are working hard to prepare communities with no
previous experience of such an event.
Non-evacuation in Tarō was reportedly caused by the communication of information that the
expected tsunami was only 3 m – this led to public perception that the town would be
protected by its tsunami defences, and some were sceptical that a tsunami would arrive at
all. Following the natural and formal warnings, some residents in Tarō waited in the town for
family members to drive home from elsewhere in order to evacuate together. This had not
only the effect of delaying the person in Tarō, but encouraging those in other locations to
drive into the hazard zone, with the result that some were unnecessarily killed during
inundation. The desire to evacuate with family was also reported in Kamaishi, where
residents are reported to have died while driving through the city having collected family
members.
In Kesennuma the disaster prevention official we interviewed believes that people should be
encouraged to help others in the stages of disaster preparation and post-evacuation, rather
than during the event when they should be concentrating on evacuating the hazard zone
themselves. In this way, people would be encouraged to not return or travel through
evacuation zones to help people prior to imminent tsunami arrival. He is considering
adopting the tsunami tendenko philosophy that was taught in Iwate Prefecture and attributed
to successful evacuations of schools in Kamaishi City.
These examples are important for Washington and New Zealand to consider, as delays in
evacuation are likely to cause many deaths in a local tsunami event, and education should
be put in place specifically to reduce this potential issue. Adoption in Washington and New
Zealand of a tendenko-like strategy encouraging self-evacuation and not stopping to help
others would be a significant change from current advice, which emphasises the importance
of immediate evacuation but does not explicitly advise “leave others behind” or “look after
only yourself”. In fact, advice from FEMA (2011) states the opposite, which may result in
further deaths from people remaining in the inundation zone too long:
“Remember to help your neighbors who may require special assistance - infants, elderly
people, and individuals with access or functional needs.”
Delays in evacuation were also caused by perceptions of safety close to the edge of the
recognised hazard zone. In Ōfunato City, most people in the official (and mapped) hazard
zones evacuated quickly, whereas those just outside the mapped hazard zone tended to not
evacuate until they saw the tsunami coming close to their immediate location. This effect
was seen in Minami-Sanriku, where neighbourhood fatality rates are higher in
neighbourhoods immediately inland of the mapped tsunami hazard zone, where people
perhaps perceived themselves to be safe. Murakami and Kashiwabara (2011) also suggest
this effect occurred in Natori City, where fatality rate in Yuriage 2 chome is 22%. In
comparison areas closer to the fishing harbour, suffered 11-12% a lower fatality rate
(Figure 33).
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