Following the announcement of the “Massive Earthquake Warning,” we asked a researcher into the mechanisms behind earthquakes what he thinks about the possibility that the earthquake on the 8th and the Nankai Trough earthquake are linked.

On the 8th, the Japan Meteorological Agency issued its first emergency information for the Nankai Trough earthquake, “Caution for a Massive Earthquake,” stating that the possibility of another massive earthquake occurring in conjunction with the earthquake that occurred in the Hyuga-Nada Sea is higher than usual.

Yohei Hamada, a senior researcher at the Kochi Core Research Institute in Nankoku City, Kochi Prefecture, who studies the mechanisms behind earthquakes, has also conducted research off the coast of Hyuga-Nada, and says that this area is a place where many large earthquakes occur.

(Yohei Hamada, Chief Researcher)
“Looking back through history, many earthquakes have occurred in the Hyuga-Nada area. Looking at the timeline, five major earthquakes have occurred since the 1900s.”

What concerns me is the possibility of it being linked to the Nankai Trough earthquake.

(Yohei Hamada, Principal Researcher)
“The relationship between earthquakes is still in its infancy, and we don’t yet know in detail how earthquakes are linked or how they spread. Looking at history, we have never seen a Hyuga-nada earthquake linked to a Nankai earthquake. However, this is only a historical period, so on the scale of several thousand years, which we do not have in our records, there is a possibility that the Hyuga-nada and Nankai Trough earthquakes are related.”

The Japan Meteorological Agency also estimates that there is a 0.5% chance of a major earthquake occurring within the next week, and the prefecture is also calling for people to be on alert for about a week. Why one week?

(Yohei Hamada, Principal Researcher)
“It has been confirmed that one week after an earthquake of magnitude 7 or so occurs, an earthquake of the same magnitude or larger will occur. There have also been cases of earthquakes of the same magnitude occurring after that, so the risk does not go to zero. As a guideline, it is recommended to be especially careful for about a week.”

Chief Researcher Hamada says that regardless of whether a major earthquake occurs or not, he hopes that this “Massive Earthquake Warning” will serve as an opportunity to reconsider earthquake preparations.

(Yohei Hamada, Principal Researcher)
“Earthquakes happen all the time, without warning. However, this time the warning was issued with the possibility of linked earthquakes in mind, but I would like everyone to remember once again that we should always be prepared for earthquakes that occur without warning, and I hope that this will be an opportunity for everyone to take another look at their earthquake preparations.”

As specific preparations, the prefecture is calling for people to confirm evacuation routes and how to contact each other as family members in the event of an emergency, as well as reviewing their stockpiles and securing furniture.