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Educational guide, not an alert service: no live data. Always follow official instructions from JMA, your municipality, police, fire and staff. In an emergency, protect yourself first. Full disclaimer

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Japan alert decoder · 北海道・三陸沖後発地震注意情報

Off the coast of Hokkaido and Sanriku Subsequent Earthquake Advisory

Prepare and check your route · official rules as of 2026-10-17

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Prepare and check your route

北海道・三陸沖後発地震注意情報

Off the coast of Hokkaido and Sanriku Subsequent Earthquake Advisory

An Mw7.0+ earthquake happened off Hokkaido / Sanriku (Japan Trench / Kuril Trench), so a following megaquake is relatively more likely for about a week. Issued about 2 hours after the first quake for Pacific coast areas from Hokkaido to Chiba. It is not a prediction.

What to do now

  1. Keep daily life, but sleep in clothes you can evacuate in and keep shoes and an emergency bag by the door.
  2. Be ready to evacuate at once if you feel shaking or get a tsunami warning.

How long: About one week (168 hours).

Issued by: JMA and the Cabinet Office. Live status: JMA warnings map (English)JMA earthquake information (English)JMA tsunami information (English)

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Educational guide, not an alert service: no live data. Always follow official instructions from JMA, your municipality, police, fire and staff. In an emergency, protect yourself first.

Data as of 2026-10-17 from official JMA, Cabinet Office, Cabinet Secretariat (J-ALERT) and Ministry of the Environment pages, with official names from the JMA multilingual dictionary (2026-03-26). Not affiliated with JMA or any government agency.

Educational guide, not an alert service: no live data. Always follow official instructions from JMA, your municipality, police, fire and staff. In an emergency, protect yourself first. Data as of 2026-10-17 from official JMA, Cabinet Office, Cabinet Secretariat (J-ALERT) and Ministry of the Environment pages, with official names from the JMA multilingual dictionary (2026-03-26). Not affiliated with JMA or any government agency.