At Least 520,000 Japanese may Face Advance Evacuation for Nankai Quake

At least 520,000 people across Japan could be asked to evacuate for a week if authorities issue a special alert signaling an elevated risk of a massive Nankai Trough earthquake, a government survey revealed, Kyodo News reported.

The Japan Meteorological Agency would issue a “megaquake alert” if a magnitude 8 or stronger quake occurred in the expected source region, and the likelihood of subsequent tremors was judged high. (Photo: 徳島地方気象台 Wikimedia Commons) 

It was the first nationwide survey by the Cabinet Office on areas designated for such preemptive evacuations. The number of municipalities with these designations remains limited, but the scope is expected to expand—potentially raising the total figure further.

The Nankai Trough, located off the Pacific coast of central Japan, is a zone known for generating megaquakes.

The government has urged municipalities in at-risk areas to hold regular evacuation drills for both major earthquakes and tsunamis.

The survey found that roughly 245,600 residents would face evacuation in areas where all citizens are designated, while about 274,800 people live in areas where only those requiring special care—such as the elderly or disabled—are included.

The Japan Meteorological Agency would issue a “megaquake alert” if a magnitude 8 or stronger quake occurred in the expected source region and the likelihood of subsequent tremors was judged high.

Regions where post-quake evacuation would be impossible due to tsunami risk are required to conduct one-week pre-evacuations, Mainichi Japan also reported.