This week, seismic intensity 4 occurred one after another in various places.

I think some people may be worried that it is a harbinger of a huge earthquake.


A person in charge of the Japan Meteorological Agency said, "There are certainly many," but "it is unlikely that they are related to the activities of each region."

Experts point out that the areas that have been shaking recently have a unique background and require caution.



The latest views are summarized by region.

(* An article on earthquake preparedness is also posted at the end of the article)

Japan Meteorological Agency "I think there are certainly many"

During the week leading up to April 7, there were earthquakes in Tohoku, Kanto, Kinki, Hokuriku, and Tokai that observed shaking with seismic intensities of 3 and 4.

Looking at the seismic intensity of 4 or higher, 17 times from last month to the evening of the 8th.

This is certainly more than it was three times in January and February.

Regarding the relationship between a series of earthquakes, Kazuki Miyaoka, an earthquake information planner of the Japan Meteorological Agency, said at a regular press conference explaining seismic activity on the 8th, "There are certainly many earthquakes with a seismic intensity of 4 or higher."



"Just ..." said Planning Officer Miyaoka.

"Seismic activity is not uniform, and there are many and few periods. I think that this period was concentrated and an earthquake of a certain scale occurred, and I think it is particularly abnormal. I haven't. "



It is unlikely that the activities of each region are related.

On the other hand, both the Japan Meteorological Agency and experts say that there are points to be aware of in each region.

[Kanto] Seismic activity remains high

First is Kanto.



On April 2, a shaking with a seismic intensity of 4 was observed in Ibaraki Prefecture.

There was an earthquake with the epicenter of Tokyo Bay on the 31st of last month, and a seismic intensity of 4 was observed in Chiba prefecture, and a shaking of 3 was observed in Tokyo, Kanagawa and Saitama prefectures.



Regarding the earthquake around Tokyo Bay, the Japan Meteorological Agency says that it is close to the epicenter where the shaking with a seismic intensity of 5 or higher was observed last October.

Originally it is an area where seismic activity is active, but it has become more active since the huge earthquake 11 years ago.

Professor Shinji Toda of Tohoku University, who is familiar with the mechanism of the earthquake, said, "Although a tremor with a seismic intensity of about 4 usually occurs directly under the Kanto region, it is stimulated by a huge earthquake and its activity is active. , It still tends to stay high, so please be careful in the future. "

[Tokai / West Japan] Is the inland earthquake active before the Nankai Trough earthquake?

On the other hand, Professor Toda points out that "it may increase in the future" is an earthquake that occurs directly under the inland areas of Tokai and western Japan such as Aichi and Wakayama prefectures.

Experts have pointed out that "earthquakes directly below the inland area become active during the period before and after the Nankai Trough giant earthquake."



Regarding the background, Professor Toda points out, "If the inland area is continuously pushed in the process of a huge earthquake, strain will accumulate in the inland area and earthquakes will be more likely to occur."

The epicenter is directly below the land and it may be shallow, so even if the magnitude is not so large, the shaking will be severe and there is a risk of damage.

It is necessary to be careful because the earthquake in northern Osaka prefecture four years ago caused a lot of damage such as the collapse of the block wall.

[Tohoku] "Two areas of concern"

It is Tohoku that is expected to continue shaking for a long time in the future.

Off the coast of Fukushima Prefecture, there have been a series of earthquakes following a major earthquake with a magnitude of 7.4 that observed shaking with a maximum seismic intensity of 6 or higher on the 16th of last month.

Professor Toda points out that the earthquakes in Tohoku were affected by the huge earthquake 11 years ago in a broad sense.

This figure compares the activity of the earthquake in the five years until last year and the five years before the great earthquake by Professor Toda.

The redder it is, the more active it is.



The recent earthquakes are a mechanism called "intraslab earthquakes" that occur inside the plate.

Professor Toda points out that in addition to the intra-slab earthquake, attention should be paid to the "outer rise earthquake" that occurs further east of the epicenter area of ​​the huge earthquake.



Professor Toda said, "Earthquakes in the coastal areas near the inland area tend to have high seismic intensity and it is necessary to be careful about shaking. I need it. "

[Noto region] Is it related to the mysterious uplift?

Although the reason is not clear, it is the Noto region of Ishikawa prefecture that needs to be vigilant in the future.



Seismic activity has been active since around December 2020, and


the number of earthquakes that have observed seismic intensity 1 or higher since the beginning of this year is


▽ 6 times in


January ▽ 6 times in February


▽ 22 times in March. Rapid increase.


▽ Seismic intensity 4 is also observed in April.


The area where the earthquake is occurring is concentrated around Suzu City on the north side of the Noto Peninsula.

As a result of detailed analysis by the Japan Meteorological Agency, the area where the earthquake is occurring is mainly divided into four areas, and it is particularly active in the two areas on the north side.



Experts are paying attention to the uplift of the ground that is being observed at the same time.

At the observation point in Suzu City, the ground has risen by more than 3 cm so far.

Associate Professor Takuya Nishimura of the Kyoto University Disaster Prevention Research Institute says that some fluid may have flowed underground and seismic activity may have become active, and he is calling attention to large-scale earthquakes in the future.

[Preparation 1] What to do when an earthquake occurs !?

What should we do when a big earthquake occurs?

When a big earthquake occurs, an Earthquake Early Warning may be announced, but if it is close to land, it may not be in time.

First of all, it is important to ensure your safety.



<In the case of indoors>


Keep away from the hanging lights.

If you are on the elevator, stop at the nearest floor and get off.


<Outdoor> In the


past, some people were involved in the collapse of block walls.

If you are outside, it is important to stay away from blocks and buildings.

What to do when an earthquake occurs !?

* Click here to find out more about the response immediately after the earthquake.

[Preparation 2] Check the stockpile

I thought "let's stockpile", but isn't it left as it is?

First of all, please check the water and food as well as the small stove.

If you want to stay at home, the "toilet" is also important.

Let's stockpile for life before a disaster

* Click here to find out more about stockpiling

[Preparation 3] Response to power outages

I'm sure some of you have experienced a power outage right after the earthquake.

After the earthquake off the coast of Fukushima Prefecture, power saving was also called for.



In the event of an actual power outage, it is useful to have a battery for your smartphone.


In order to reduce the power consumption of the smartphone,


▽ "Low power mode", "Battery saver", etc.


▽ Reduce the screen brightness, or set it to "Dark mode", etc. for a long time.

If there is a power outage ... What about your smartphone?

What about the lights?

What to watch out for?

* Click here for how to use your smartphone or light in the event of a power outage