Tsunami Warning in Japan: What to Do, and the Flags and Signs

If a tsunami warning sounds in Japan, or you feel strong shaking near the coast, evacuate immediately to high ground or a tsunami evacuation building, on foot, and stay there until the warning is lifted. The Japan Meteorological Agency (JMA) says a tsunami can arrive before any warning is issued, so do not wait to see the water.

1. The three levels JMA uses

After an earthquake that could cause a disastrous tsunami, JMA issues warnings about three minutes later, or as early as two minutes in some cases. It uses three categories:

For huge earthquakes JMA may first give only a qualitative word, "Huge" or "High", because the exact magnitude takes time to determine. If you see "Huge", JMA says tsunamis as large as those after the 2011 Great East Japan Earthquake may hit, and you should evacuate to the safest place possible. Major Tsunami Warnings are issued as Emergency Warnings.

2. Do not leave early, and do not go back

JMA's guidance includes four points worth memorizing:

• Evacuate when you feel strong shaking, or weak shaking that lasts a long time, even if no warning has come yet.
• Tsunami heights can exceed estimates in some places, so keep moving to higher ground where you can.
• Waves arrive repeatedly, and later waves may be higher.
• Do not leave the evacuation location until the warnings are cleared.

JMA also uses the phrase "Currently Observing" in some bulletins. JMA uses it when observed tsunamis appear much smaller than estimated, to keep people aware that higher waves may still approach. The Cabinet Office, fire agency and JMA leaflet adds: "If you see a tsunami, it's already too late to evacuate," and tells people to evacuate on foot to avoid traffic jams.

3. The tsunami flag

Since summer 2020, coastal areas have shown a red and white checkered flag to signal a tsunami warning. JMA says it was introduced to help hearing-impaired people and swimmers who may not hear sirens over waves and wind, and that its design is similar to the U-flag used internationally as a marine warning. JMA's instruction is simple: evacuate immediately if you see a tsunami flag. The leaflet notes that a flag may also be displayed on a building. Warnings also come by TV, radio, mobile phone, sirens and warning bells.

4. Reading the signs on the coast

The leaflet explains the sign symbols used on local tsunami hazard maps and signboards:

• Tsunami refuge area and tsunami refuge building: a SAFE refuge from a tsunami.
• Tsunami hazard zone: a DANGER of tsunami.
• Tsunami flag: tsunami warnings are issued.

JMA and the leaflet urge people in coastal or riverside areas to check the locations of evacuation areas and buildings on the local government hazard map in advance.

5. Phrases to ask for help

The Japanese word for tsunami is 津波 [tsunami], which is standard vocabulary rather than text from the sources above. For asking where to go, JNTO's disaster phrase cards print:

• 避難所はどこですか？ [hinanjo wa doko desu ka] "Where is the emergency shelter?"
• ここは安全ですか？ [koko wa anzen desu ka] "Is it safe here?"
• 一緒に来てください。 [issho ni kite kudasai] "Could you come with me?"

More phrases for the minutes after shaking are in this guide to Japanese phrases for an earthquake or other disaster.

6. Get alerts on your phone

JNTO's Safety tips site says that after an earthquake, JMA issues a tsunami warning in about three minutes and that you should remain in a safe place until it is cancelled, because tsunamis strike repeatedly over a long period. The Safety tips app page says it pushes tsunami warnings and other alerts in English and 14 other languages.

7. Key takeaways

• Strong shaking near the coast means go to high ground now; do not wait for a warning.
• Major Tsunami Warning and Tsunami Warning mean evacuate to high ground or a tsunami evacuation building; an Advisory means get out of the water.
• A red and white checkered flag means evacuate immediately.
• Waves repeat and later ones can be higher, so stay until the warning is lifted.
• 避難所はどこですか asks where the shelter is.