Weekly earthquake information 2024.10.27 9 felt earthquakes in one day in northern Wakayama Prefecture, the highest seismic intensity 3

At approximately 7:08 am on Wednesday the 23rd, an earthquake estimated to have a magnitude of 4.0 and a depth of 5km occurred with its epicenter in northern Wakayama Prefecture.

As a result of this earthquake, the highest seismic intensity of 3 was observed in Wakayama City and Kinokawa City, Wakayama Prefecture. This is the first earthquake with a seismic intensity of 3 or higher centered in the northern part of Wakayama Prefecture since February this year. The mechanism of the earthquake is being investigated to be strike-slip type.

After the magnitude 3 earthquake occurred, aftershocks occurred sporadically throughout the night, and nine felt earthquakes were observed in one day.

Although there are no known active faults around the epicenter of this earthquake, the area is prone to seismic activity due to the different angles of subduction of the Philippine Sea Plate and geological influences. Earthquakes with a magnitude of around 5 occur frequently, and since the depth of the epicenter is very shallow, less than 10 km, because in this case, the shaking can be great.

Recently, almost 50 earthquakes were felt between February and March 2021. On March 15 of the same year, an earthquake occurred with a magnitude of 4.6 and a maximum seismic intensity of just under 5.

The government’s Headquarters for the Promotion of Earthquake Research estimates that there is a 70-80% chance that an earthquake with a magnitude of around 7.1 will occur in the Hyuga-nada Sea within the next 30 years, and this earthquake seems to be identical with this.

An assessment review meeting was held because the epicenter was within the Nankai Trough mega-earthquake monitoring area and the magnitude was 6.8 or higher. As a result, it was determined that the probability of a large earthquake occurring in the Nankai Trough earthquake is relatively high compared to the normal times, and the Nankai Trough earthquake emergency information (main earthquake warning) to issue.

This is the first time this information has been announced since it started working in 2019. e

If you are already well prepared for an earthquake, please review your preparedness, and if you are not, now is the time to review your product disaster prevention, evacuation routes, hazard maps, etc.

At approximately 15:19 on the 21st (Monday), an earthquake estimated at a magnitude of 3.8 and a depth of 17 km occurred with its epicenter in the central west of Mino, Gifu Prefecture.

As a result of this earthquake, a maximum seismic intensity of 3 was observed in Ichinomiya City, Aichi Prefecture, and a seismic intensity of 2 was observed in the western part of Aichi Prefecture and the Mino area of ​​Gifu Prefecture. This is the first earthquake with a seismic intensity of 3 or higher in the central and western Mino region of Gifu Prefecture since March this year.

Gifu Prefecture has many active faults. The Yoro-Kuwana-Yokkaichi fault zone extends to the southwest of the prefecture, but the epicenter of this earthquake was slightly away from the fault zone.

At approximately 12:29 on Saturday the 10th, an earthquake estimated at magnitude 6.8 and a depth of approximately 490km occurred with its epicenter in the southern part of the Sea of ​​Okhotsk. As a result of this earthquake, a seismic intensity of 3 was observed in Hakodate City, Hokkaido, Hachinohe City, Mutsu City, Hashikami Town, and Hiranai Town, Aomori Prefecture, and Morioka City, Iwate Prefecture.

In this earthquake, there were few places where a seismic intensity of 1 or higher was observed on the Sea of ​​Okhotsk side of Hokkaido, which is near the epicenter, and a seismic intensity of 3 was observed on the Tohoku Pacific side, which is far from the center.

In the case of a large-scale deep earthquake, a distribution of seismic intensity called an “abnormal seismic region” can be seen, where strong shaking is transmitted far away. Although it is called an anomaly, it is a phenomenon that often occurs during deep earthquakes.

In deep earthquakes, strong shaking is transmitted along the subsurface plate, and the shaking can be large at a distance near the plate boundary. In this earthquake, it is thought that the shaking moved to the coast of the Pacific Ocean in Hokkaido and Tohoku on the Pacific Plate, where seismic waves can move easily.

Similar earthquakes have occurred in the Sea of ​​Okhotsk in the past, with a magnitude 7.3 earthquake in 2012 causing tremors that reached as far as the Kanto region. Large, deep earthquakes can cause strong tremors far from the epicenter, so you need to be careful.

According to a study by the US Geological Survey, one earthquake with a magnitude of 6 or higher has occurred. The largest earthquake occurred in the southern part of the Kamchatka Peninsula with a magnitude of 6.2.

Late at night on the 23rd (Wednesday) Japan time, an earthquake estimated at magnitude 6.2 and a depth of about 49 km occurred with its epicenter in the waters south of the Kamchatka Peninsula. The mechanism of the earthquake is studied as a type of reverse fault with a stress axis running northwest-southeast.

The area from the southern end of the Kamchatka Peninsula to the Kuril Islands is an area where many earthquakes occur as a result of the Pacific plate joining the North American plate. In 2020, a magnitude 7.5 earthquake occurred near the epicenter. A tsunami of up to 0.5 m was observed in the Kuril Islands due to this earthquake.

On the night of the 5th (Friday, Japan time), an earthquake that was estimated to have a magnitude of 4.8 and a depth of about 5 km occurred with its epicenter in New Jersey, near New York. The earthquake mechanism is considered to be strike-slip.

This earthquake is believed to have caused shaking of magnitude IV on the revised Mercalli intensity scale, even in central New York. Although a precise comparison is not possible, the shaking corresponds to a seismic intensity level of 1 to 2 on the Japanese seismic intensity scale.

Earthquakes are rare in the northeastern United States, including the New York area, and only 40 earthquakes of magnitude 3 or greater have occurred within 250 km of the epicenter. -average since 1950. Among them, this size 4.8 is the largest.

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