Japan's tsunami warnings explained: Major Tsunami Warning, Tsunami Warning, Tsunami Advisory
JMA issues tsunami warnings and advisories for each coastal region about three minutes after an earthquake, and in some cases as early as two minutes. There are three levels. Knowing what each means saves the seconds you'd otherwise spend wondering.
The three levels (JMA)
| Level | Expected height | Heights announced | Expected damage | Action |
|---|---|---|---|---|
| Major Tsunami Warning (an Emergency Warning) | Greater than 3 meters | Over 10 m, 10 m, 5 m; or "Huge" | Wooden structures completely destroyed or washed away; anybody exposed will be caught in tsunami currents | Evacuate from coastal or river areas immediately to high ground or a tsunami evacuation building |
| Tsunami Warning | Up to 3 meters | 3 m; or "High" | Damage to low-lying areas; buildings flooded; anybody exposed caught in currents | The same: evacuate immediately |
| Tsunami Advisory | Up to 1 meter | 1 m | Strong currents in the sea; fish farms washed away; small vessels may capsize | Get out of the water and leave coastal areas immediately |
The words "Huge" and "High" appear when an earthquake is too large to size quickly. JMA explains that for magnitude 8 or more it issues an initial warning based on the predefined maximum magnitude, to avoid underestimating. If a Major Tsunami Warning says "Huge", tsunamis as large as those after the Great East Japan Earthquake of 2011 may hit.
Five rules for evacuating
- Don't wait for the warning. If the source is near the coast, a tsunami can arrive before any warning. Evacuate when you feel strong shaking, or weak shaking that goes on for a long time (JMA). And huge tsunamis can strike even without shaking you can feel (JMA leaflet).
- Go on foot. JMA's leaflet says to evacuate on foot to avoid traffic jams.
- Keep climbing. Coastal shape can make a tsunami higher than estimated, so don't assume you're safe; keep moving to higher ground (JMA).
- Don't come back early. Waves hit repeatedly and later ones may be higher. Don't abandon evacuation because the first waves were small, and don't leave the evacuation site until the warnings are cleared (JMA).
- Advisory means out of the water. If you're in the ocean, get out immediately and move away from the shore (Japan Tourism Agency).
Signs to recognize
At beaches, watch for tsunami flags: JMA's leaflet says they feature a red and white checkered pattern. If you see one, leave the water and the beach.
Our suggestions
- At a coastal campsite, find the evacuation route before you pitch the tent.
- Agree on a meeting point with your group in case you're separated.
- Combine this with Earthquakes in Japan and Japan's five alert levels.
Everyday
At any beach, coastal campsite or riverside hotel in Japan, find the route to high ground or a tsunami evacuation building when you arrive.
When it counts
If you feel strong or long shaking near the coast, you go to high ground on foot, without waiting for the warning.
Sources and when we checked them
- Japan Meteorological Agency, Tsunami Warning/Advisory and Tsunami Information (last modified 2023-04-11) (checked 2026-10-31)
- Japan Meteorological Agency, Earthquake! Tsunami! Evacuate immediately! (leaflet, PDF) (checked 2026-10-31)
- Japan Tourism Agency, Safety tips for travelers: tsunami (last modified 2024-10-29) (checked 2026-10-31)
- Japan Tourism Agency, Safety tips for travelers (home) (checked 2026-10-31)
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