As travelers book flights to Tokyo, the Japanese government warns that residents near Tokyo should prepare for potentially larger earthquakes following a surge of seismic activity offshore.
Japan’s Earthquake Research Committee announced on November 13 that seismic events have grown increasingly frequent off the coasts of Chiba and Ibaraki prefectures.
Recent weeks brought a string of notable tremors to the Tokyo metropolitan region, including a magnitude 6.1 earthquake on November 6 at 7:39 p.m., centered roughly 202 kilometers east-southeast of Chiba City at a depth of 10 kilometers, according to the Japan Meteorological Agency. That event produced no impact in South Korea, the agency noted.
The Earthquake Research Committee documented 11 separate earthquakes with a seismic intensity of 1 or higher across the region stretching from northeastern Chiba to its eastern offshore waters during October.
Investigators are examining whether the late-October activity links to a slow slip phenomenon, wherein tectonic plate boundaries shift gradually over days or months rather than snapping instantly. While slow slip generates little noticeable shaking for humans, it transfers stress to neighboring faults and can trigger subsequent earthquakes. The committee stated it is currently analyzing observation data to determine any direct correlation.
| Date | Location | Magnitude | Depth |
|---|---|---|---|
| September 29 (Prior) | Chiba Prefecture offshore | 5.4 | Not specified |
| November 6 | Chiba City East-Southeast offshore | 6.1 | 10 km |
| November 9 | Ibaraki Prefecture offshore | 5.9 | Not specified |
Given the pattern of recent offshore activity in Ibaraki Prefecture this month, the committee emphasized that the possibility of larger earthquakes occurring in the future cannot be ruled out.
