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■ Deep earthquakes with abnormal seismic areas are a precursor to great earthquakes!
On the morning of December 1, a large earthquake of M6.6 and a depth of 610 km occurred off the west coast of Sakhalin. Generally, the seismic intensity of an earthquake is highest near the source and decreases as it propagates concentrically. However, at this time, a seismic intensity 1 was observed in Miyagi prefecture, which is 1000 km from the source of the earthquake. An area in which an earthquake occurs far from the source is called an “abnormal seismic area” in seismology.
Also, an earthquake that occurs when the depth of the source is 200 km or more is called a “deep earthquake”, but this time the source is 610 km deep, which is much larger than that. Most earthquakes with abnormal seismic areas are deep earthquakes, but it is extremely rare for an earthquake with a depth of more than 600 km to occur around Japan. According to a search site for the Meteorological Agency’s seismic intensity database, it has only happened 26 times in the last 100 years.
In any case, isn’t this something that is happening? As I proceeded with the analysis, I noticed a terrifying law. When a deep earthquake occurs with an abnormal seismic area around the Japanese archipelago in this way, it often happens that a large earthquake will continue several days or two months later. Also, since the lunar eclipse and the great solar flare occur at the same time, we must be on the alert for a great earthquake. Let’s explain in detail at once.
■ Deep earthquake → Abnormal seismic area → Giant earthquake … Positional relationship of fear
By the way, the earthquake of the day is a deep earthquake with a depth of 600 km, but if you look at the deep earthquakes with a depth of 350 km or more that occurred in the last 100 years near the Japanese archipelago, it looks like a dogleg as shown in the figure above. You can see that it is distributed in. In this way, deep earthquakes occur in a limited area, and are said to occur below the “plate subduction zone” where the plate is subducted below other plates.
Next, the source of the deep earthquake (1), the abnormal seismic area where the tremor was observed farthest from it (2), and the source of the subsequent large earthquake (3). Let’s draw it on the map. Then it became clear that there were two patterns. Let’s illustrate this on the map.
[Patrón A]Transition linearly
(1) 1921/10/12 16:52 South of the Okhotsk Sea, M6.3, depth 405 km, maximum seismic intensity 1
(2) Akita City, Akita Prefecture (seismic intensity 1)
(3) 1921/12/08 21:31 Ryugasaki Earthquake, M7.0
(1) 2008/09/06 00:12 Off the southeast coast of Mie prefecture, M5.6, depth 419km, maximum seismic intensity 2
(2) Rikuzen Takada City, Iwate Prefecture
(3) 2008/09/11 09:20 Off Tokachi, M7.1, 5 minor maximum seismic intensity
[Patrón B]Large earthquakes continue around the abnormal seismic area
(1) 07/21/1923 01:49: Off the south side of Tokaido, 394 km deep, maximum seismic intensity 1
(2) Chiyoda-ku, Tokyo (seismic intensity 1)
(3) 1923/09/01 11:58, Kanto Earthquake, M7.9, Maximum seismic intensity 6
(1) 2011/01/13 06:32: West of the Ogasawara Islands, M7.1, depth 516km, maximum seismic intensity 2
(2) Iwanuma City, Miyagi Prefecture
(3) 2011/03/11 14:46: Offshore Pacific Ocean earthquake in Tohoku region, M9.0, maximum seismic intensity 7
Not all deep earthquakes with anomalous seismic areas are related to larger earthquakes. Also, there are some that do not apply to the above two patterns, and it is better to consider that trend to some extent. However, if a deep earthquake with abnormal seismic area and depth of 350 km or more occurs in the past, a large earthquake will occur in Japan within a few days to two months, especially as in pattern A. There are many cases of Transition.