Archive · 10 Dec 2025
Japan Issues First-Ever 'Subsequent Earthquake' Advisory
Japan has issued its first-ever 'Subsequent Earthquake' advisory, warning about the possibility of very high tsunami waves.
The government's simulations from 2021 show that in the worst case, waves could be over 30 meters high in some areas.
These areas include parts of eastern Hokkaido and the Sanriku Ria Coast, which has a lot of narrow inlets and steep cliffs.
These features could make the waves even bigger and more dangerous.
The advisory is to help people prepare and stay safe in case a big earthquake happens and causes a tsunami.
Japan issued its first-ever 'Subsequent Earthquake' advisory.
Government simulations predict waves over 30 meters in extreme cases.
Affected regions include eastern Hokkaido and the Sanriku Ria Coast.
The area's narrow inlets and dramatic terrain could amplify the waves.
The advisory aims to warn and prepare people for potential tsunamis.
- Who
- Japan's Cabinet Office’s Central Disaster Management Council
- What
- Issued a first-ever 'Subsequent Earthquake' advisory and released tsunami simulations
- When
- Simulations released in 2021, advisory issued recently
- Where
- Hokkaido–Sanriku region, eastern Hokkaido, Sanriku Ria Coast
- Why
- To warn about the potential for high tsunami waves following an earthquake
- Advisory Issued
- First-ever 'Subsequent Earthquake' advisory
- Potential Tsunami Height
- Over 30 meters in extreme cases
- Affected Regions
- Hokkaido–Sanriku region, eastern Hokkaido, Sanriku Ria Coast
- Source of Information
- Government simulations released in 2021 by the Cabinet Office’s Central Disaster Management Council
- Terrain Impact
- Narrow inlets and dramatic terrain could amplify waves