What are Japan's three tsunami warnings, and what should I do?

JMA issues three categories about three minutes after a large earthquake: a Major Tsunami Warning (expected height over 10 m, 10 m or 5 m, or the word 'Huge'), a Tsunami Warning (3 m, or 'High') and a Tsunami Advisory (1 m). For both warnings the instruction is to evacuate from coastal or river areas immediately to high ground; for an advisory, get out of the water and leave the coast. If you are near the sea when the ground shakes hard, move to high ground without waiting for the warning.

The three categories

Category	Expected height	What JMA expects	What JMA tells you to do
Major Tsunami Warning	over 10 m / 10 m / 5 m, or "Huge"	Wooden structures are expected to be completely destroyed and/or washed away	Evacuate from coastal or river areas immediately to safer places such as high ground
Tsunami Warning	3 m, or "High"	Tsunami waves will hit, causing damage to low-lying areas. Buildings will be flooded	Evacuate from coastal or river areas immediately to safer places
Tsunami Advisory	1 m	Anybody exposed will be caught in strong tsunami currents in the sea	Get out of the water and leave coastal areas immediately

"Huge" and "High" appear when the earthquake is so large that JMA cannot yet give a number. Treat them as the top of the scale.

The one rule

Near the coast, strong or long shaking means go to high ground now, on foot. Japan's tourism organization: If you are by the coast when a large earthquake strikes, head for higher ground in case of a tsunami.

Waves come in sets

JMA: Tsunami waves are expected to hit repeatedly. Do not leave the tsunami evacuation location until Tsunami Warnings are cleared. Rivers count too: a tsunami runs up rivers far inland.

The live warnings, in your language

Japan Disaster Guide is a free iPhone app that delivers JMA warnings for the places you save, after JMA confirms them, in 7 languages, with 115,000+ evacuation sites on a map.

Free on the App Store See the Japan Travel Safety Kit

The full procedures, the 119 script, shelter life, the 171 steps, 21 pointing cards and the worksheets are in the Japan Travel Safety Manual, a 66-page PDF made to read on a phone.

Get the manual ($9.99 PDF)

Sources (read 2026-09-09; quotations are verbatim)

Japan Meteorological Agency, Tsunami Warnings/Advisories and Tsunami Information (English). https://www.data.jma.go.jp/eqev/data/en/guide/tsunamiinfo.html
JNTO, Staying Safe in Japan. https://www.japan.travel/en/plan/emergencies/

Japan Disaster Guide is an independent app. It is not affiliated with the Japan Meteorological Agency or any government body. In an emergency, follow the instructions of local officials.

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