TOKYO (Kyodo) — The Japanese government on Tuesday released new damage estimates under the scenario of a magnitude-9 level earthquake hitting off the Pacific coast of northeastern and northern Japan, warning up to 199,000 people in seven prefectures, including Hokkaido and Aomori, could die.
The Central Disaster Management Council predicts that most of the fatalities will be caused by the resulting tsunami, and a maximum of 220,000 buildings could be destroyed if such a quake occurs along the Japan Trench. The potential economic fallout for the region and country as a whole could be roughly 31.3 trillion yen ($275.4 billion).
Based on proposals regarding also Chishima Trench to be created by the council early next year, the government will speed up the process of updating disaster management measures, given that the estimated deaths in the northeastern and northern areas could be reduced by 80% if timely evacuations are made.
The Japan Trench stretches off Hokkaido to east of the Boso Peninsula near Tokyo, while the Chishima Trench lies off the country’s main northern island to the Chishima Islands, also known as the Kuril Islands.
The Japanese government has been reviewing its disaster management following the 2011 earthquake and tsunami that devastated northeastern Japan.
Earthquakes with a magnitude greater than 7 have occurred around the trenches in the past. In the previous assessment released in 2006, it was estimated that up to 2,700 people could die in the event of a strong temblor. However, the assessment did not consider a powerful quake with a magnitude of 9 or higher jolting the region.
The government has already completed its review on two other possible massive quakes — Nankai Trough and Tokyo Inland.
It has been estimated that up to 323,000 people could die in a trench-type earthquake occurring along the Nankai Trough stretching from off western to central Japan, and 23,000 in a quake inland of Tokyo.
For the Japan Trench and Chishima Trench estimates, the council considered several different scenarios depending on the season and time of day of the disaster.
The worst-case scenario is a megaquake in the vicinity of the Japan Trench in late hours in winter, allowing only 20% of residents to evacuate promptly.
Under such a scenario, 137,000 could die in Hokkaido, 41,000 in Aomori, and 11,000 in Iwate. The council says the public needs to be aware that if necessary steps are taken, including building tsunami evacuation towers and more quake-resistant structures, the total number of deaths would be significantly lower, at roughly 30,000.
Most of the building damage will be caused by a tsunami, and the number of evacuees would reach up to 901,000 by the following day of a magnitude-9 level quake, according to the assessment.
Concerning the potential economic impact, the destruction of buildings and infrastructure in the affected region would account for 25.3 trillion yen and the remaining approximately 6 trillion yen is expected to spill over to the rest of the country.
A megaquake in the vicinity of the Chishima Trench could kill 100,000 people in the seven prefectures, including Fukushima and Ibaraki, and destroy 84,000 buildings.
The estimates did not refer to nuclear power plants in Aomori, Miyagi, Fukushima, and Ibaraki prefectures. The government has said it will not predict possible damage linked to a specific facility.
They are based on tsunami predictions released by an expert panel of the Cabinet Office in April 2020.
The panel said the height of the tsunami could reach 29.7 meters in Miyako, Iwate Prefecture, and 27.9 meters in Erimo, Hokkaido if a megaquake occurs around the two trenches.