The Nankai Trough earthquake has already begun. “The Nankai Trough earthquake has already started, and the Philippine Sea Plate is under a heavy load due to the activation of the Pacific Plate. The earthquakes and volcanic eruptions that have been occurring in various regions are evidence of this. It would not be surprising if a huge earthquake far beyond the government’s expectations were to occur at any time.
On the morning of December 3, strong earthquakes of intensity 5 and below occurred at Fuji-Goko in Yamanashi Prefecture and Kii Suido in Wakayama Prefecture. In addition, more than 200 tremors have been continuously observed in the sea near the Tokara Islands in Kagoshima Prefecture since December 4 (as of December 7).
The “Nankai Trough” is the name given to a 4,000-meter-deep trench that runs about 700 kilometers from the Tokai region to western Shikoku. The Nankai Trough is where the Philippine Sea Plate sinks deep beneath the Eurasian Plate, and 10 major earthquakes have been recorded there in the past. Takahashi says that the countdown has finally begun.
Please take a look at the map. The areas marked in black are the ones most likely to be hit by a huge earthquake of intensity 6 or lower within 30 years. Most of them are concentrated on the Pacific side along the Nankai Trough. In this area, 37 earthquakes of intensity 4 or higher occurred between January and December 5 this year. This is almost double the number from the same period two years ago. Clearly, there is something wrong with the ground that supports the Japanese archipelago. Dr. Toshiyasu Nagao, a visiting professor at Tokai University and the director of the university’s Earthquake Prediction and Volcanic Tsunami Research Division, said, “The Japanese archipelago is characterized by earthquakes and volcanoes.
In the Japanese archipelago, earthquakes and volcanic activity repeatedly go through periods of calm and periods of increased activity. Since the Great East Japan Earthquake in 2011, earthquakes and volcanic activity have been increasing. The eruption of Fukutoku Okanoba near Iwo Jima, which is now causing the pumice stone problem, is a notable example, and we will continue to have many earthquakes and eruptions.
Takahashi points out that the movement of the Pacific Plate in particular is becoming more active.
Between August and September of this year, the entire Japanese archipelago began to move southwestward, and in November it moved northeastward. In November, it moved to the northeast, and in a short period of time, it changed to the exact opposite direction. This unstable movement is the result of the Pacific Plate compressing and dragging down other plates. As a result, the whole of Japan is affected, and earthquakes and eruptions are occurring all over the country.
Earthquakes have been occurring in Wakayama Prefecture, near the Nankai Trough, and in Yamanashi Prefecture, where Mt. Fuji. Mr. Nagao, mentioned above, said.
The earthquakes in Yamanashi and Wakayama prefectures occurred within the Eurasian plate and the North American plate, respectively. The earthquakes in Yamanashi and Wakayama prefectures occurred within the Eurasian plate and the North American plate, respectively, and both were caused by the release of strain accumulated by the pushing of the Philippine Sea plate.
According to Takahashi, it is not a coincidence that the two earthquakes occurred on the same day.
According to Takahashi, it is not a coincidence that the two earthquakes occurred on the same day. “The Pacific Plate is moving the Philippine Sea Plate. The Philippine Sea Plate is also responsible for the swarm of earthquakes that have been occurring near the Tokara Islands since December 4. It is noteworthy that the depth of the epicenter of earthquakes in the Tokara Archipelago has been 10 km or less in the past, but this time many earthquakes have been recorded at a depth of 20 km or more. The trend is clearly different from previous earthquakes. Earthquakes and volcanic eruptions are occurring in a wide area of the Philippine Sea Plate. This phenomenon is the beginning of the ‘Nankai Trough Mega Earthquake (Super Nankai Earthquake)’.”
According to a CG simulation prepared by the Cabinet Office, the estimated magnitude of the “Nankai Trough Mega Earthquake” is 9, with tremors of up to intensity 7 hitting cities such as Tokyo and Osaka. Houses and roads would be destroyed, and fires would occur as a secondary disaster. If a huge tsunami were to hit, the damage would be even more devastating.
Simulations estimate the death toll at over 320,000. We need to be prepared to survive.
From FRIDAY, December 24, 2021
PHOTO： Asahi Shimbun (2nd photo)