Weekly Earthquake Information 2022.2.20 Seismic intensity 4 or higher has been a M5.3 earthquake off the coast of Miyagi prefecture since May last year –Weathernews

2022/02/20 11:32 Weathernews

The number of earthquakes observed in Japan in the past week has decreased compared to the previous week.

Earthquakes are conspicuous on the Pacific side from Kanto to northern Japan. There are two earthquakes with a seismic intensity of 3 or higher during this period. (Aggregation from February 14th to 20th at 10:00)

Domestic: M5.3 off the coast of Miyagi prefecture, shaking over a wide area with a seismic intensity of 3 or higher

Earthquake off the coast of Miyagi Prefecture

At around 11:55 on the 18th (Friday), there was an earthquake with a magnitude of 5.3 and an estimated depth of 52km that originated off the coast of Miyagi prefecture. Due to this earthquake, we have observed shaking with a maximum seismic intensity of 4 in Osaki City and Ishinomaki City, Miyagi Prefecture, and a seismic intensity of 3 in a wide range from Iwate Prefecture to Miyagi Prefecture and Fukushima Prefecture.

This is the first earthquake with a seismic intensity of 4 or higher off the coast of Miyagi prefecture since the magnitude 6.8 (maximum seismic intensity 5+) that occurred on May 1, last year. The mechanism of the earthquake seems to be a reverse fault type with a pressure axis in the east-west direction.

Earthquake-prone area at the plate boundary

Epicenter distribution off the coast of Miyagi Prefecture

This earthquake is close to the epicenter of the above-mentioned May magnitude 6.8 earthquake last year, and the mechanism is the same. Off the coast of Miyagi prefecture, the Pacific plate is subducting into the land plate, and the depth of regarding 50 km is close to the plate boundary, which is an area where earthquakes occur frequently.

In August 2013, there was an earthquake with a magnitude of 6.0 and a maximum seismic intensity of 5 or higher, and in April, immediately following the huge earthquake that caused the Great East Japan Earthquake in 2011, a strong earthquake with a magnitude of 7.2 also occurred.

The government’s Earthquake Town Research Promotion Headquarters has set a 20% probability of an earthquake with a magnitude of 7.9 and a 90% probability of an earthquake with a magnitude of 7.0 to 7.5 occurring at the plate boundary off the coast of Miyagi prefecture within 30 years. Please take appropriate measures on a daily basis.

Keep an eye on the tendency for activities to subside

Seismic activity in the waters near the Tokara Islands became active around noon on the 4th (Sat). The number of felt earthquakes with a seismic intensity of 1 or higher has reached 277 by 24:00 on the 10th (Friday).

Looking at the number of earthquakes by day, the number of earthquakes on the 5th (Sun) is the highest at 87. On the 9th (Thursday), when an earthquake with a seismic intensity of 5 or higher occurred, there were 36 times, which was a little high, but on the 10th (Friday), it was only 5 times, and the activity as a whole tends to be settled.

However, during the activity in October 2000, when the same tremor with a seismic intensity of 5 or higher occurred, an earthquake with a seismic intensity of 4 occurred regarding 3 weeks following the active state settled down. You need to be careful regarding strong shaking for a while.

Domestic: Earthquake swarm from Saturday, 4th in the Tokara Islands

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 regarding strong shaking for a while.

World: Deep-focus earthquake M6.8 in the waters near Fiji has no major impact

World M4.5 or higher earthquake (USGS homepage quote / Weathernews processing)

Two earthquakes with a magnitude of 6 or greater have occurred, as analyzed by the United States Geological Survey. The largest earthquake has a magnitude of 6.8 near Fiji.

An earthquake with a magnitude of 6.8 and an estimated depth of regarding 535km occurred in the waters south of Fiji in the South Pacific on the early morning of Thursday, 17th Japan time. The mechanism of the earthquake is analyzed as a normal fault type with a tension axis in the east-northeast-west-southwest direction. Since the epicenter was deep, there was no damage from the tsunami or shaking.

The sea near Fiji is an area where the Pacific plate and the Australian plate are intricately intricate and earthquakes occur frequently. There are many large deep-focus earthquakes similar to this one, and recently there was a magnitude 7.3 earthquake last October. In 2018, there were a series of earthquakes with a magnitude of 8.2 and a magnitude of 7.9.

M5.0 earthquake in the middle of Africa

An earthquake with a magnitude of 5.0 and an estimated depth of regarding 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.