Survey: 585 Areas Have Locations Where Residents Would Have Difficulty Escaping from Tsunami; Over 230,000 People Affected

The Yomiuri Shimbun

17:06 JST, March 24, 2025

Over 230,000 residents in at least 585 areas across Japan are at risk of being unable to escape tsunami, according to a Yomiuri Shimbun survey conducted on relevant municipalities.

Many municipalities that responded so are located in areas at risk of tsunami caused by megaquakes in the Japan and Chishima trenches and Nankai Trough. Some of the municipalities have tens of thousands of residents.

The actual number may be even higher because just under 20% of the municipalities were either under inspection or have not yet performed inspections on the matter when Yomiuri sent questionnaires between January and March.

According to the Fire and Disaster Management Agency (FDMA), difficult-to-escape areas are defined as areas that are deemed difficult for their residents to escape to a safer location before the arrival of the highest possible tsunami. The government urges municipalities to specify such difficult-to-escape areas in their tsunami evacuation plans that are compiled based on the Law on the Promotion of Tsunami Countermeasures.

In 2020, the FDMA asked 675 relevant municipalities if they have any such area but did not check how many nor the population there. The Yomiuri Shimbun then collected the latest data from all the 284 municipalities — excluding ones that responded to the FDMA survey as having no difficult-to-escape area — this year, inquiring about how any areas exist and their populations.

The Yomiuri survey found that 585 areas in 79 municipalities — or 12% of all 675 municipalities concerned — in 25 prefectures are designated as an area where it is difficult to escape from tsunami, and 233,000 people in total live in such an area. Iwaki in Fukushima Prefecture is notable for having the highest population of 51,000 in such areas, followed by Fujisawa in Kanagawa Prefecture with 40,398 and Kuwana in Mie Prefecture with 24,233.

Regarding the reasons for having difficult-to-escape areas — with multiple answers allowed — 65% said there is no high ground or there are no tall buildings nearby, while 16% said they have no suitable location nor budget to build evacuation towers.

An earthquake is expected to occur in the Japan and Chishima trenches, or north of the Great East Japan Earthquake’s epicenter, causing tsunami up to 30 meters high and a death toll of 199,000, according to a government estimate. A Nankai Trough Earthquake could cause tsunami to span from the Kanto region to Okinawa Prefecture and kill an estimated 323,000 people.

Among municipalities designated by the government to reinforce their evacuation plan, 177 areas, with a population of about 88,000 in total, in 16 municipalities in seven prefectures are found to be in a difficult area to escape tsunami triggered by a quake in those trenches. In the case of a Nankai Trough earthquake, 160 areas with about 87,000 people in 24 municipalities in seven prefectures, including Mie, Wakayama and Miyazaki, will fall into the same situation.

In the Yomiuri survey, 20 municipalities said they did not have accurate figures about populations of affected areas, while 61 said they were in the process of conducting or planning to conduct a survey. Fifty-four said they have not conducted such a survey. The remaining 90 did not have such an area.

When combining the Yomiuri and FDMA surveys, Hyogo, Okayama and Kochi prefectures said they did not have any difficult-to-escape areas. Kochi Prefecture said it has already taken countermeasures such as by building evacuation towers.

“The public and private sectors should work together to eliminate [the number of] difficult-to-escape areas by widening roads to facilitate evacuation by car or building towers,” said Toshitaka Katada, a project professor at the University of Tokyo.