Weekly Earthquake Information 2024.8.18 Seismic activity has increased in western Kanagawa Prefecture since the earthquake intensity dropped to magnitude 5 on Friday the 9th – Weather News

2024-08-18 00:53:00

2024/08/18 09:53 Weather News

The number of felt earthquakes observed in Japan over the past week was lower compared to the previous week. Earthquakes are somewhat noticeable in the Kanto and Kyushu regions, where a major earthquake occurred last week. Three or more earthquakes occurred. (Statistics from August 12th to 18th at 10 a.m.)

Domestic: Magnitude 4 and 3 earthquakes with epicenter in western Kanagawa Prefecture

Western Kanagawa Prefecture Earthquake

At around 20:20 on Thursday, the 15th, an earthquake with a magnitude of 4.3 and a depth of 12 kilometers occurred in western Kanagawa Prefecture. The maximum intensity of this earthquake was 4 in Nakai Town, Kanagawa Prefecture, and 3 in Sagamihara City, Odawara City, Qinno City, Atsugi City, Isehara City, Hiratsuka City and other places.

In addition, on Wednesday, the 14th, a magnitude 4.2 earthquake occurred at roughly the same epicenter, and a maximum earthquake intensity of magnitude 3 was observed.

These earthquakes are related to an earthquake that occurred on Friday the 9th, with a magnitude of 5.3, and the maximum earthquake intensity was just below magnitude 5. The epicenter and depth are basically the same, and the mechanism is consistent with the type of reverse fault with the pressure axis running roughly north-south.

Seismic activity continues to be more active than usual, with magnitude 3 and 4 earthquakes occurring. There have been no felt earthquakes since the early hours of Friday the 16th.

In the past, earthquakes of similar magnitude have occurred in the area, followed by a magnitude 3 earthquake weeks later. Please be aware that a magnitude 3 earthquake may occur in areas close to the epicenter.

Temporary Information Announcement for the First Nankai Trough Earthquake

The Japanese Government’s Earthquake Research Promotion Headquarters estimates that there is a 70-80% chance of an earthquake of around magnitude 7.1 occurring in Hyuga-nada within the next 30 years, and this earthquake appears to be comparable to that.

Because the epicenter was located in the Nankai Trough Extraordinary Earthquake Monitoring Area and the magnitude was above 6.8, an assessment and review meeting was held. As a result, it was judged that the possibility of a large-scale earthquake in the Nankai Trough earthquake was higher than usual, and the Nankai Trough earthquake emergency information (major earthquake warning) was issued.

This is the first time this information has been announced since it began operations in 2019. Should

If you’re already prepared for an earthquake, check your preparedness again. If you’re not, check your disaster supplies, evacuation routes, hazard maps, etc. now.

Domestic: Earthquake offshore Miyagi Prefecture, maximum intensity level 3

An earthquake occurred offshore Miyagi Prefecture

At around 9:33 on Saturday, the 17th, an earthquake with a magnitude of 4.5 and a depth of approximately 50 kilometers occurred off the coast of Miyagi Prefecture, the epicenter of the earthquake. The maximum intensity of this earthquake in Iwanuma and Ishinomaki cities in Miyagi Prefecture was magnitude 3.

This is the first magnitude 3 earthquake to occur along the coast of Miyagi Prefecture since the 23rd of last month. The source analysis is a reverse fault type, and the pressure cycle is from west-northwest to east-southeast.

Although the offshore area of ​​Miyagi Prefecture is an earthquake-prone area, no earthquake of magnitude 3 or above has occurred since October last year. After the first magnitude 3 earthquake in 10 months was observed on the 21st of last month, another earthquake occurred on the 23rd. This was the first earthquake since then. The epicenter and depth are almost the same as those of the earthquake on the 21st.

Even after the Great East Japan Earthquake in 2011, earthquakes of magnitude 6 occurred frequently along the coast of Miyagi Prefecture. In 2021, two earthquakes with a maximum intensity of magnitude 5 or above occurred. Although the situation has remained relatively calm this year, it is not surprising that a major earthquake can occur at any time, and preparation is essential.

Domestic: Sea of ​​Okhotsk M6.8 deep earthquake

At around 12:29 on Saturday, the 10th, an earthquake with an epicenter located in the southern Sea of ​​Okhotsk occurred. It was estimated to have a magnitude of 6.8 and a depth of approximately 490 kilometers. The magnitude of this earthquake was 3 in Hakodate City and Hachinohe City in Hokkaido, Mutsu City, Hashiage Town, Hiraiuchi Town in Aomori Prefecture, and Morioka City in Iwate Prefecture.

In this earthquake, there were very few places with seismic intensity above 1 degree on the Sea of ​​Okhotsk side of Hokkaido close to the epicenter, while seismic intensity of 3 degrees was observed on the Northeast Pacific side, which was far away from the epicenter.

When a large-scale deep earthquake occurs, a seismic intensity distribution called an “abnormal seismic zone” will appear, and strong vibrations will be transmitted to long distances. Although it is called an anomaly, it is a phenomenon that often occurs in deep earthquakes.

In deep earthquakes, strong shaking propagates along the subducting plate, and the shaking becomes larger closer to the plate boundary. In this earthquake, the shaking is thought to have spread along the Pacific Plate to Hokkaido and the Pacific coast to the northeast, where seismic waves propagate easily.

Similar earthquakes have occurred in the Sea of ​​Okhotsk in the past, including a 7.3-magnitude earthquake in 2012 that caused vibrations that even spread to the Kanto region. Large, deep earthquakes can cause strong shaking far from the epicenter, so caution is required.

World: M6.1 earthquake near Taiwan

Global M4.5 and above earthquakes (USGS home page citation/weather news processing)

According to analysis by the United States Geological Survey, two earthquakes of magnitude 6 or above have occurred. The largest earthquake occurred along the coast of Kamchatka Peninsula with a magnitude of 7.0.

This time we focus on the Taiwan earthquake. On the morning of the 16th (Friday), Japan time, an earthquake occurred along the eastern coast of Taiwan. The earthquake was estimated to have a magnitude of 6.1 and a depth of about 14 kilometers. The mechanism of earthquakes is that the pressure axis extends from west-northwest to east-southeast.

The Taiwan Meteorological Administration said an earthquake with a magnitude of 4 was observed in a wide area, including Hualien County. Taiwan’s earthquake intensity is magnitude 10, the same as Japan’s. A magnitude 1 earthquake was also observed in Ishigaki City, Yonaguni Town and other places in Japan.

The earthquake occurred near the epicenter of a 7.4-magnitude earthquake in April that caused heavy damage. However, it is a bit far away from the active area of ​​​​the April earthquake, so it is not clear whether it is a series of events.

The east coast of Taiwan is located at the junction of the Eurasian Plate and the Philippine Sea Plate and is a prone area for major earthquakes. Since 2000 alone, including this year, there have been three magnitude 7 earthquakes.

World: Rare earthquake hits New York

On the evening of the 5th (Friday, Japan time), an earthquake with a magnitude of 4.8 and a depth of about 5 kilometers occurred in New Jersey, near New York. The earthquake mechanism is speculated to be a strike-slip earthquake.

The quake is thought to have caused a magnitude IV earthquake on the revised Mercalli intensity scale even in central New York. Although it is impossible to compare precisely, the earthquake was equivalent to an earthquake intensity level of 1 to 2 on Japan’s seismic intensity scale.

The northeastern United States, including the New York area, has relatively few earthquakes. Since 1950, only 40 earthquakes of magnitude 3 or above have occurred within 250 kilometers from the epicenter. Among them, this earthquake with a magnitude of 4.8 is the largest.

In addition, the 5.8-magnitude earthquake that occurred in Virginia in August 2011 is known as the earthquake that caused tremors in New York and other areas.

Source/Reference
*Unless otherwise stated, information on Japan’s epicenter and intensity comes from the Japan Meteorological Agency. Unless otherwise stated, overseas epicenter information comes from the United States Geological Survey (USGS). The epicenter information may vary depending on the issuing agency.

Reference materials, etc.

1723979241
#Weekly #Earthquake #Information #2024.8.18 #Seismic #activity #increased #western #Kanagawa #Prefecture #earthquake #intensity #dropped #magnitude #Friday #9th #Weather #News