The study’s aim is to identify the challenges in estimating personal damages in the early stages of a disaster.

The study reviewed personal damage data in the reports on the Great East Japan earthquake and tsunami published by Japanese public agencies from 2011 to 2020, including 159 situation reports by the Fire and Disaster Management Agency and 17 disaster-related indirect death reports by the Reconstruction Agency. The study compared the reported number of deaths, missing persons, and injuries with the latest statistics to evaluate how soon the disaster’s real damages were estimated.

The reported number of deaths significantly increased in the first 1.5 years, whereas the number of missing persons spiked in the first 30 days. It required approximately 1 year until the numbers approximated the current reference rate. The total casualties included 3739 indirect deaths.

The results indicated an overestimation of missing persons, a possible underestimation of injuries, and the excess deaths due to indirect causes that complicated the estimation. The limitations of the current data collection approaches are the delay in reporting from the field and incomplete and unreliable information. A novel system is proposed, which directly collects data from all affected individuals anonymously.