Weekly Earthquake Information 2022.4.24 Maximum seismic intensity 5 lower in Ibaraki Prefecture This year’s 6th earthquake of 5 lower or higher –Weathernews

2022/04/24 10:32 Weathernews

The number of earthquakes observed in Japan in the past week is not much different from the previous week.

During this period, earthquakes were conspicuous on the Pacific side of northern Japan from the Kanto region, and western Japan also occurred in some parts of the inland area. On the other hand, the earthquake off the northwest coast of Okinawa was in a lull. There have been two earthquakes with a seismic intensity of 3 or higher. (April 18-April 24 10:00 total)

Domestic: M5.4 in northern Ibaraki prefecture, seismic intensity 5 lower or higher is the 6th time this year

Earthquake in northern Ibaraki prefecture

Around 8:16 on Tuesday, 19th, there was an earthquake with a magnitude of 5.4 and an estimated depth of 93km with the epicenter in the northern part of Ibaraki prefecture. Initially, the epicenter was Nakadori, Fukushima Prefecture, but later analysis corrected the epicenter and changed it to northern Ibaraki Prefecture.

Due to this earthquake, the maximum seismic intensity is 5 lower in Shirosato Town, Ibaraki Prefecture, and the seismic intensity is 4 in a wide range from Fukushima Prefecture to Kanto such as Shirakawa City and Iwaki City, Fukushima Prefecture, Mito City, Ibaraki Prefecture, Hitachi City, Utsunomiya City, Tochigi Prefecture, and Kuki City, Saitama Prefecture. Was observed. The mechanism of the earthquake is analyzed as a strike-slip type.

This is the sixth earthquake in Japan with a seismic intensity of 5 lower or higher since the earthquake off the coast of Iwate Prefecture on March 18.

Area where there are not many earthquakes even in northern Ibaraki prefecture

Epicenter distribution in northern Ibaraki prefecture

Although it is in the northern part of Ibaraki prefecture, which is one of the most earthquake-prone areas in the Kanto region, there are not many earthquakes near the epicenter this time. There are few earthquakes that exceed magnitude 5, dating back to the magnitude 5.2 earthquake that occurred in 1949.

The strong earthquake near the epicenter this time is not considered to require much caution. On the other hand, there are so many earthquakes in the area east of the epicenter that we can call it an “earthquake nest.” This is the 11th earthquake since 2001 that has observed a seismic intensity of 5 lower or higher in an earthquake whose epicenter is in the northern part of Ibaraki prefecture. It can be said that daily preparation is essential.

Domestic: Earthquake with a maximum seismic intensity of 3 in Yamaguchi Prefecture

Earthquake in central Yamaguchi Prefecture

Around 7:46 on Saturday, 23rd, there was an earthquake with a magnitude of 4.2 and an estimated depth of about 10km with the epicenter in central Yamaguchi Prefecture. Due to this earthquake, a maximum seismic intensity of 3 has been observed in Yamaguchi City, Hofu City, Shunan City, etc., and a seismic intensity of 2 has been observed in parts of Fukuoka Prefecture and Oita Prefecture. The mechanism of the earthquake is analyzed as a strike-slip type.

Central Yamaguchi Prefecture is not an area where earthquakes occur frequently, and earthquakes of magnitude 4 and above have been occurring since 1997. The earthquake that occurred on June 25, 1997 was in the area north of the epicenter this time, but we have observed a magnitude of 6.6 and a maximum seismic intensity of over 5.

This earthquake occurred far from the active faults known in Yamaguchi Prefecture. According to the evaluation by the Headquarters for Earthquake Research Promotion of the government, the activity of the Suo-nada fault zone distributed off the coast of Yamaguchi Prefecture is the most concerned, and the probability that an earthquake with a magnitude of 7.6 will occur within the next 30 years is 2 to 4%. It has been.

Domestic: M4.4 in southern Kyoto

Earthquakes have occurred frequently in the sea near the Tokara Islands in the Amami region of Kagoshima prefecture from around noon on the 4th (Sat). The first felt earthquake had a magnitude of 2.9 and a maximum seismic intensity of 1 at around 12:32 on Saturday, 4th, and an earthquake of magnitude 4.0 and a maximum seismic intensity of 3 occurred at 19:48. After that, the earthquakes continued, and as of 10 o’clock on the 5th (Sun), there were 87 felt earthquakes, of which 6 were earthquakes with a seismic intensity of 3.

These earthquake swarms often occur in the waters near the Tokara Islands. Recently, earthquakes have occurred frequently since April 9th ​​this year, and on April 10th, more than 100 felt earthquakes occurred in one day. During the three days from the 10th to the 12th, which was the peak of activity, we observed 229 felt earthquakes, 15 seismic intensity 3 and 5 seismic intensity 4.

In many cases, the active situation from past activities lasts for several days, and the maximum seismic intensity may reach a little over 4-5. It is necessary to be careful about strong shaking for a while.

World: M6.7 earthquake off the coast of Nicaragua, Central America

World M4.5 and above earthquakes (USGS homepage quote / Weathernews processing)

Three earthquakes with a magnitude of 6 or greater have occurred, as analyzed by the United States Geological Survey. The largest earthquake occurred along the coast of Nicaragua with a magnitude of 6.7.

An earthquake with a magnitude of 6.7 and an estimated depth of 25 km occurred on the coast of Nicaragua, Central America, on the evening of Thursday, 21st Japan time. The mechanism of the earthquake is analyzed as a reverse fault type with a pressure axis in the northeast-southwest direction.

Although the magnitude of the earthquake was rather large, the epicenter was a little far from the land, so there was no impact from the shaking and no tsunami that would cause damage.

The coast of Nicaragua is the boundary between the Cocos Plate and the Caribbean Plate, and earthquakes often occur due to the subduction of the plate. In 2004, there was a magnitude 7.0 earthquake near the epicenter, and in 1992, there was a magnitude 7.7 earthquake. The 1992 earthquake caused a tsunami and caused great damage.

M5.0 earthquake in the middle of Africa

An earthquake with a magnitude of 5.0 and an estimated depth of about 10 km occurred in Congo, Africa, before noon on Wednesday, 26th Japan time. The epicenter of this earthquake is on the west side of the area called the “Great Rift Valley”.

Most African earthquakes occur around the Great Rift Valley. The African Continent is made up of African plates, and the Great Rift Valley is thought to be the area where the plates are being torn. In its activities, it has caused earthquakes, and in the past, magnitude 7 class earthquakes have also occurred.

Reference materials, etc.

* Information on the epicenter and seismic intensity in Japan is from the Japan Meteorological Agency unless otherwise stated. Information on overseas epicenters is from the United States Geological Survey (USGS) unless otherwise stated. The epicenter information may differ depending on the issuing organization.