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01/17/2021 10:26 Weather News
In the last week, the number of earthquakes observed in Japan has increased slightly compared to the previous week. There have been no earthquakes with a seismic intensity of 3 or more. During this period, there were many earthquakes from eastern Japan to northern Japan. (Added from January 11 to January 17 at 10:00)
In addition, around 10:39 p.m. on Friday the 15th, an earthquake with a magnitude of 5.3 and a depth of approximately 364 km occurred off the southeast coast of Mie Prefecture. In this earthquake, a maximum seismic intensity of 2 was observed mainly in Kanto region, such as Shirakawa city, Fukushima prefecture, Mito city, Ibaraki prefecture, Hitachi city, Utsunomiya city, Tochigi Prefecture and Chiyoda District, Tokyo.
All earthquakes were “deep earthquakes” with a depth of 100 km or more, and “abnormal seismic areas” were observed in which relatively strong shaking was observed at a distance from the source. Especially in the case of an earthquake on the southeast coast of Mie prefecture, there is nowhere where a seismic intensity of 1 or more has been observed in the Tokai region near the center of the earthquake, but it is a typical distribution with the strongest shaking in northeast Kanto and Fukushima prefectures.
As at this time, the depth of the earthquake source is deeper than 100 km, and 210 earthquakes have occurred in the 10 years from 2011 to 2020, in which tremors with a seismic intensity of 2 or more were observed somewhere in the Japanese archipelago. On average, it happens once or twice a month, which is not a rare earthquake.
Since the source of the earthquake is deep, strong tremors are not easily transmitted to the ground, and although there are few earthquakes that cause damage, 3 out of 210 observations have a seismic intensity of 5 less, so be careful. He’s a good guy to keep.
Similar deep earthquakes often occur where the Pacific plate is deeply subducted, with earthquakes of magnitude 6 and above occurring once every few years. On the other hand, it is also characterized by the fact that there are almost no after-effects from a single earthquake.
A 6.2 magnitude earthquake occurred near the island of Sulawesi, Indonesia, on the 15th (Friday) of Japan time. Since the source of the earthquake was land and the depth was relatively shallow at 18 km, it appears that the revised Mercari seismic intensity class reached VII (equivalent to a 4 to 5 lower seismic intensity in the Japanese seismic intensity class) near from the source of the earthquake. I am.
Many buildings collapsed in the area affected by strong tremors and more than 40 people died, according to the Indonesian government’s National Agency for Disaster Prevention.
The island of Sulawesi was hit by a large magnitude 7.5 earthquake in 2018 and was severely damaged by strong earthquakes and tsunamis, including more than 4,000 deaths. Since the source is far from this earthquake and the mechanism is different, it appears that it is not a directly related earthquake.
* Information on the source and intensity of seismic intensity in Japan comes from the Meteorological Agency, unless otherwise noted. Unless otherwise noted, overseas seismic source information comes from the American Geological Survey (USGS). Source information may differ depending on the issuing organization.
