Japan's government updates damage estimates for a Tokyo quake

In early December 2025, a Japanese government panel under the Cabinet Office, which coordinates national disaster policy, released updated estimates of the damage that could follow a major earthquake directly beneath the Tokyo region. The same review also covered the effects of a possible eruption of Mount Fuji, whose ash could spread across the capital area.

The estimates looked at casualties, destroyed buildings, economic losses and disruption to transport, power, water and communications. They replaced earlier projections that dated back several years, taking into account changes in population, construction standards and disaster preparedness.

The update mattered because Tokyo concentrates Japan's government, financial markets, major companies and much of its population. Analysts and officials noted that a severe quake or heavy ashfall could paralyse central ministries, the Diet (parliament) and the Bank of Japan at the same time, with consequences for the national and global economy.

The findings added weight to a long-running debate about reducing this concentration, including how to keep government working if Tokyo were hit, and fed into later discussions about designating a backup capital.