``Slow slip'' occurs off the eastern coast of Chiba Prefecture as seismic activity continues? Geographical Survey Institute of Japan

An analysis by the Geospatial Information Authority of Japan has revealed that a ``slow slip,'' in which the boundary between the land-side plate and the sea-side plate is slowly shifting, appears to be occurring off the eastern coast of Chiba Prefecture, where seismic activity continues.

A series of earthquakes have been occurring off the eastern coast of Chiba Prefecture since the 27th of last month, with a magnitude 5.2 earthquake occurring one day earlier, and shaking of magnitude 4 being observed in Chiba and Saitama prefectures.

According to the Geospatial Information Authority of Japan, which uses satellites to observe crustal deformation, unusual changes have been occurring on the Boso Peninsula since around the 26th of last month.

As a result of analysis based on this crustal movement, it appears that a ``slow slip'' is occurring off the eastern coast of Chiba Prefecture, in which the boundary between the land-side plate and the sea-side plate slowly slips, and the maximum amount of slippage is approximately It is estimated to be 2 cm.

"Slow slips" have been observed six times off the eastern coast of Chiba Prefecture from 1996 to 2018, and seismic activity has increased during the same period.

In the past, ``slow slips'' lasted for about two weeks, so the Geospatial Information Authority of Japan will continue to monitor the situation closely.

Expert: “Prepare for shaking while continuing your normal life”

According to Professor Takuya Nishimura of the Disaster Prevention Research Institute, Kyoto University, who specializes in crustal deformation, the ground on the east side of the Boso Peninsula usually moves northward, but on the 27th of last month, it was observed that it was moving almost in the opposite direction, toward the southeast. This means it has been confirmed.

Professor Nishimura said, ``In this region, slow slips last for about a week or 10 days, but we need to be careful about seismic activity for about a month.The Noto Peninsula earthquake also occurred in January, but there is no need to be too afraid. "It's not good. I want people to double check their preparations for the shaking while continuing their normal lives."