Earthquake swarm at the central epicenter of Nagano Prefecture "Attention for a while" April 27, 18:55
Earthquakes centered on central Nagano Prefecture have swarmed since early this month, including the observation of a seismic intensity of 3 in Matsumoto City, Nagano Prefecture on the 27th. Experts point out that "we need to be careful about landslides and avalanches associated with shaking for a while".
In central Nagano prefecture, there have been a series of earthquakes since the beginning of this month, and a magnitude 5.5 earthquake occurred on the 23rd of this month, and we have observed a seismic intensity of 4 in Matsumoto City.
By the end of this month, there were 57 earthquakes with a seismic intensity of 1 or more, which occurred in the central part of Nagano Prefecture, starting in this month.
According to Shiro Omi, an associate professor at the Disaster Prevention Research Institute of Kyoto University, who is familiar with seismic activity in this area, it is said that there are several hundred earthquakes, including shaking that is not felt by the body.
It is also said that seismic activity begins near the Tokumoto Pass on the eastern edge of the Kamikochi basin and gradually spreads toward the northwest.
According to Associate Professor Omi, swarm earthquakes have repeatedly occurred in this area in the past, and recently there was activity in Otoshito in November, as well as immediately after the 2011 Great East Japan Earthquake and in 1998. There was a great amount of seismic activity.
Previous studies have shown that the region has soft magma up to the shallow underground, and the hard rock that causes the earthquake is relatively thin, and the magnitude of the earthquake is about magnitude 5 to 5.5.
Associate professor Ohmi said, "There is a possibility that the earthquake will continue for a while. I think there are no tourists due to the new coronavirus, but since the epicenter is shallow, there is a possibility that strong shaking will occur near the epicenter even if the magnitude is small. Therefore, we need to be careful about landslides and avalanches. "
On the other hand, at Yakedake near the epicenter, there are no abnormalities in data such as crustal movements so far, and there are no signs of a large eruption.