Mortality in the 2011 tsunami in Japan

On 11 March 2011, a magnitude 9.0 earthquake caused a huge tsunami that struck Northeast Japan, resulting in nearly 20 000 deaths. We investigated mortality patterns by age, sex, and region in the 3 most severely affected prefectures.

Using police data on earthquake victims in Iwate, Miyagi, and Fukushima prefectures, mortality rates by sex, age group, and region were calculated, and regional variability in mortality rates across age groups was compared using rate ratios (RRs), with the rates in Iwate as the reference.

In all regions, age-specific mortality showed a tendency to increase with age; there were no sex differences. Among residents of Iwate, mortality was markedly lower among school-aged children as compared with other age groups. In northern Miyagi and the southern part of the study area, RRs were higher among school-aged children than among other age groups.

The present study could not address the reasons for the observed mortality patterns and regional differences. To improve preparedness policies, future research should investigate the reasons for regional differences.