Weekly Earthquake Information 2021.1.24 Peak 3 Earthquake off Fukushima Prefecture About 3 weeks have passed since New Year’s Day –Weathernews

Around 1:04 a.m. on Saturday the 23rd, there was an earthquake with a magnitude of 4.6 and an estimated depth of about 30 km, which originated off the coast of Fukushima Prefecture. With this earthquake, we have observed a maximum seismic intensity of 3 in the cities of Naraha and Futaba, Fukushima prefecture, and a seismic intensity of 2 in the cities of Iwaki, Shirakawa, Ishinomaki, Miyagi, etc.

This is the second time a seismic intensity of 3 or more has been observed in Japan since the maximum seismic intensity of 4 was reached in the earthquake near Niijima and Kozushima that occurred on January 1, shortly after the start of the year.

The area in front of Fukushima prefecture is the area of ​​the aftershock of the great earthquake that occurred in 2011, and it is an area with many earthquakes. In the second half of last year, the occurrence of strong shaking earthquakes has stabilized, and the seismic intensity of 3 or more is the first in about half a year since July 17. Even if the intervals between earthquakes increase slightly, they are only within the margin of error in terms of long-term activities, and there is no change in terms of areas where earthquakes are likely to occur.

Please be sure to prepare for an earthquake regularly.

At around 12:57 AM on the 24th (Sunday), there was an earthquake with a magnitude of 3.9 and an estimated depth of about 10 km, which originated in the Kumamoto region of Kumamoto prefecture. With this earthquake, a maximum seismic intensity of 3 was observed in Uki city, Kumamoto prefecture, and a seismic intensity of 2 was also observed in Kumamoto city, Yatsushiro city, Misato city, Misato prefecture. Miyazaki, etc.

The epicenter of this time is the active area of ​​the Kumamoto earthquake of 2016, and the earthquake of seismic intensity of 3 or higher that occurred in this area has been since November 3 of last year. Overall activity has definitely stabilized and there was not a last earthquake in 2018 with a strong shaking with a seismic intensity of 4 or more.

In shallow earthquakes, areas with strong shaking are often concentrically distributed from the epicenter, but in deep-focus earthquakes, the seismic intensity is called the “abnormal seismic area” where the shaking is transmitted to distant areas along of the Pacific plate where seismic waves are produced. it is easily transmitted. It can be a distribution.

Similar deep-focus earthquakes often occur where the Pacific plate is deeply subducted, and earthquakes of magnitude 6 and above occur once every few years. On the other hand, it is also characterized by the fact that there are almost no aftershocks in a single earthquake.

There have been three earthquakes of magnitude 6 or greater, as analyzed by the United States Geological Survey. The largest one observes a magnitude of 7.0. Magnitude 7 and above will be the first in the world this year.

A 7.0 magnitude earthquake struck southeast of the island of Mindanao in the Philippines on Thursday 21. Although the scale was large, there was no tsunami because the depth was just under 100 km. Also, the epicenter is relatively far from the ground and there is no damage or impacts from the earthquake.

The epicenter is the region where the Philippine Sea plate is subducting towards the Eurasian plate, and the earthquake mechanism is analyzed as a type of reverse fault with a pressure axis in the east-west direction. There are many plate boundary earthquakes, and in 1969 there is a record of a 7.6 magnitude earthquake about 50 km southwest of the epicenter.

The aftershocks occurred in the area on Friday the 22nd, but all were less than magnitude 5.