💡 Why This Information Is Critical for Travelers and Residents
An important advisory, the “Post-Event Earthquake Advisory for the Hokkaido and Sanriku Coast,” has been issued by the Japanese Cabinet Office and the Japan Meteorological Agency (JMA).
This advisory is triggered when an earthquake of Magnitude (Mw) 7.0 or greater occurs along the Japan Trench or Chishima Trench, significantly raising the relative probability of a subsequent, massive earthquake (Mw 8-class or higher) during the following days.
If this advisory is issued, 182 municipalities across 7 prefectures (Hokkaido, Aomori, Iwate, Miyagi, Fukushima, Ibaraki, and Chiba) are placed under heightened alert.
If you are currently traveling or residing in these areas, understanding this advisory and knowing what steps to take is crucial for your safety.
1. Understanding the “Post-Event Earthquake Advisory”
① The Mechanism of Massive Earthquakes
The Japan and Chishima Trenches are fault lines where massive earthquakes occur cyclically every few decades to centuries. In some cases globally, a smaller “foreshock” (an initial tremor) precedes the main, massive earthquake.
The “Post-Event Earthquake Advisory” is a warning based on this possibility. When a potential “foreshock” (Mw 7.0+) occurs, the advisory signals that there is a relatively higher risk of a subsequent massive earthquake for about one week.
② Key Details of the Advisory
- Trigger Condition: An earthquake of Mw 7.0 or greater occurs in the designated source regions along the Japan and Chishima Trenches.
- Advisory Period: Approximately one week following the triggering earthquake.
Crucially, this is not a forecast that a massive earthquake is guaranteed. However, it is a call to maintain a level of preparedness much higher than normal.
2. What to Do: Specific Actions for Tourists and Residents
The advisory does not usually require a complete halt to all activities or immediate evacuation, unless local authorities specifically instruct you to do so. However, it demands that you prepare to evacuate immediately if a large tremor or official warning occurs.
🏡 Essential Safety Measures for 7 Days
| Area of Focus | Specific Action (Examples) |
| 【Rapid Evacuation Readiness】 | * Sleep in clothes you can evacuate in (wear comfortable clothes, keep warm outerwear ready, place shoes near your pillow). |
| * Keep an emergency kit close (carry it during the day, keep it next to your bed at night). | |
| * Ensure your phone/emergency device volume is high to receive early warnings. | |
| 【Danger Avoidance】 | * Stay away from dangerous coastal areas such as the ocean, rivers, and tsunami inundation zones. |
| * Avoid approaching damaged buildings or fragile concrete/block walls that may have been weakened by the initial earthquake. | |
| * If staying near a cliff, avoid sleeping in rooms closest to the slope. | |
| 【Reviewing Your Preparation】 | * Reconfirm your emergency supplies (water and food for a minimum of 3 days, preferably 7 days). |
| * Review your hotel’s/residence’s evacuation routes and designated shelters using the local Hazard Map. | |
| * Secure heavy objects and furniture. |
3. Areas Covered by the Advisory (7 Prefectures)
The advisory covers coastal and low-lying areas in:
- Hokkaido
- Aomori Prefecture
- Iwate Prefecture
- Miyagi Prefecture
- Fukushima Prefecture
- Ibaraki Prefecture
- Chiba Prefecture
[Example for Travelers] If you are staying in a popular coastal city like Hakodate (Hokkaido) or Choshi (Chiba), your accommodation staff should be able to provide specific evacuation information, as these are often included in the designated alert areas.
Always check with your hotel staff or local government website to confirm if your exact location is included in the advisory zone.
4. Conclusion: Preparedness is Key
The “Post-Event Earthquake Advisory” is a valuable warning that gives you time to enhance your readiness for a potential major disaster.
During the one-week alert period, maintaining peak preparedness and being ready to act immediately upon receiving a warning is the best way to protect yourself and those around you.
If you hear a loud siren, receive an earthquake early warning (J-Alert), or feel a strong, prolonged tremor, do not wait—evacuate immediately to a high place.
Useful Links and Information
- Cabinet Office (Disaster Management): [Please insert reliable government URL here]
- Japan Meteorological Agency (JMA): [Please insert reliable government URL here]
- For Tourists: Always follow the instructions provided by your hotel, ryokan, or tour guide.
[Call to Action]
Are you in one of the affected regions? Please take this opportunity to review your emergency procedures with your travel companions or family. Stay safe!