A Japanese government task force report revised estimates for a potential Nankai Trough megaquake, projecting economic damage up to 270.3 trillion yen ($1.81 trillion) and as many as 298,000 deaths. The figures were released Monday for the anticipated earthquake off Japan's Pacific coast.
The economic damage estimate increased from 214.2 trillion yen, reflecting inflation and updated ground data expanding potential flood areas, the Cabinet Office showed. The maximum death toll estimate decreased about 10% from 2012 due to mitigation efforts, but misses a government goal for an 80% reduction set in 2014.
Japan's government sees about an 80% chance of a magnitude 8-to-9 earthquake along the Nankai Trough zone. This seabed area runs for approximately 900 km where the Philippine Sea Plate is subducting under the Eurasian Plate.
Tsunamis could cause 215,000 of the projected deaths if only 20% of people evacuate immediately, according to the report. Increasing the evacuation rate to 70% could lower tsunami fatalities to 94,000, showing the importance of swift evacuation.
The number of potential evacuees rose to 12.3 million from 9.5 million, about 10% of Japan's population. 764 municipalities in 31 prefectures could face lower 6+ seismic intensity or tsunami waves of at least 3 meters.
Expected flood zones (30cm+) increased 30% due to better topographical data. However, the estimate for completely destroyed buildings fell slightly to 2.35 million, linked to improved residential seismic retrofitting.
The government plans to revise its disaster prevention plan, designating new priority areas based on the expanded flood risks. A new national resilience plan for fiscal 2026-2030 will also be developed to accelerate infrastructure work.
Additionally, a new agency specifically for disaster prevention is planned for establishment in fiscal 2026. Last year, Japan issued a megaquake advisory after a magnitude-7.1 quake near the trough's edge, noting a "relatively higher chance" of a large event.
