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Geologists have been pondering the scary prospect of volcanic chain reactions that, over a period of eight years, would effectively make life unlivable in Tokyo.
Mt Fuji's last eruption in the 4th year of Hoei (1707) was spectacular, scarring the mountain's southeastern slope with not one but three new craters, and marking the most violent eruption since inhabitants of the islands began keeping records from ancient times. The emitted smoke and ash of the Hoei eruption wreaked havoc on Tokyo's predecessor Edo and surrounding regions.
Based on recent geological activities, Flash (June 14) is offering some dire predictions, such as those raised by Shinji Toda, an associate professor at Tohoku University and author of a book on the phenomena of serial earthquakes.
Toda concedes that accurately forecasting a large quake occurring directly beneath Japan's capital, however, is exceedingly difficult.
"The metropolitan government foresees a quake set off by movement of the Philippine plate," Toda is quoted as saying. "But it hasn't been possible to survey how much distortion has accumulated up to now. At the very most all they can do is make a vague prediction of a 70% probability within the next 30 years."
Then we have the Tokai region, which saw several destructive quakes occurring in consecutive years, including the Tonankai quake off Wakayama in 1944 (M7.9), the Mikawa quake in Aichi Prefecture (M6.8) in 1945 and the Showa Nankai quake in 1946 (M8.0). But the section of the Tokai where major quakes have originated in the past have not seen any major temblors in the past 170 years.
The geologists are also increasingly concerned about volcanos.
"For 200 years leading up to the Hoei eruption in 1704, Mt Fuji had been dormant," pointed out geophysicist Hiroki Kamata, professor emeritus at Kyoto University. "Up to that time, the mountain had undergone repeated cyclical eruptions every half century or century."
"Mt Fuji is located just north of the area from which the Tokai earthquakes are centered," Kamata remarked. "Actually Mt Fuji was stimulated by the 2011 earthquake, and cracks were opened in the roof of its magma reservoir, putting it on a 'standby condition' for eruption, so to speak."
The aforementioned Toda described a theory among geologists that when the earth's surface is shaken by an earthquake, internal pressure builds up, causing the magma to melt and volatile gases to shoot out. "It's similar to the head of foam that forms when beer is poured," he says.
Noting that "The Japanese archipelago has become destabilized due to the Great East Japan Earthquake of March 11, 2011," Kamata mentions that "Of 111 active volcanos in Japan, 20 have been observed to have been showing new signs of activity. Eruptions have occurred at Mt Hakone in Kanagawa, Mt. Shirane on the Gunma-Tochigi border, Mt Aso in Kyushu and others."
"Forty-nine days prior to the 1704 eruption of Mt Fuji, a major earthquake occurred beneath the Nankai trough," said geophysicist Hideki Shimamura of Musashino Gakuin University, who added, "On May 24 of this year, the warning level for 2,554-meter high Mt Yakedake in Japan's Northern Alps, was raised to Level 2 (climbers advised to avoid the vicinity of the crater). Frequent earthquake activity, a harbinger of possible eruption, has been occurring in the vicinity of the mountain itself and also around the boundary of Nagano and Gifu prefectures. So sufficient possibility exists for a chain reaction of eruptions."
Should Fuji erupt after a 300-year hiatus, it would be expected that Tokyo would find itself under a heavy coating of volcanic ash.
"Volcanic ash is a fine, glassine substance," Shimamura pointed out. "People who normally wear contact lenses, for instance, would be advised to remove them, since friction from the ash can permanently damage their corneas. Public transportation, water and sewerage, the computers operated by banks, and the elevators in high-rise condominiums would risk malfunctions. And all of these are likely to impact on the lifelines people have come to rely upon."
This nightmarish scenario, of a major eruption of Mt Fuji triggered by a chain reaction of earthquakes, even now may be progressing toward an awakening from deep within the earth, Flash warns.
© Japan Today
14 Comments
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1glenn
We can be sure that there will be more volcanic eruptions. We just don't know where or when, or how strong.
One of the eruptions that worries me is the next Yellowstone Super-volcano. In the last 2 million years it has erupted three times, with up to 6,000 times the destructive force of the Mt. St. Helens eruption. The next time it erupts, it will cause major disaster in all of North America, and maybe around the world. So much destruction will occur in Canada and the USA that they will not be recognizable.
Several of the major extinction events over the last 500 million years were cause by massive, prolonged, magma eruptions. Only one extinction event was caused by an asteroid. Scientists know that one of the eruptions was in what is today India-Pakistan, and one was in what is now Siberia. They each lasted for thousands of years, causing global warming and ocean acidification such that most species were wiped out.
The Earth is a molten ball of magma and metals, with a very thin crust of solid material riding on top. That very thin crust, amounting to less than 1% of the thickness of the planet, is where we live.
virusrex
This is something that I have seen very commonly in the communications from experts, apparently the geology is not as straightforward as some shows and movies about the topic want to present.
It makes no sense getting fixated in the worst possible scenario of total destruction but so is to think nothing will happen and things will be endlessly fine. Another common thing I have seen is the advice to be prepared for some geologic disaster, to have at least the knowledge of evacuation routes and centers where the family can meet if something happens, having emergency kits available, etc.
It takes not so much money or effort, so even if (hopefully) nothing happens it is not such a big waste.
gokai_wo_maneku
Someone trying to drive down real estate prices in central Tokyo? I'm not leaving Shinjuku!
kohakuebisu
Once upon a time in prehistory, North and South Honshu were separate islands. They are now joined because of a series of massive volcanic eruptions in the channel between them. This extends from I think its Myoko and Hiuchi-dake in the north to Mt. Fuji in the south. The infilled land is known as the Fossa Magna, and was discovered and named by a German scholar in the late 1800s. Geography/geology is not my forte, but it's a really interesting story and completely non-obvious, to the point that a non-Japanese scholar had to turn up and discover it. At the west edge of the Fossa Magna, there is a plate boundary and the ISTL series of faults, which come just before (in places just hundreds of meters) the Northern Alps mountain range.
The tl:dr of the above is that there were absolutely massive eruptions in prehistory, which if repeated would probably wipe out everyone in central Japan.
Luddite
Nah, Pompeii seemed like a fun place.
Nippori Nick
Just ask the people of Kagoshima how they handle ash from eruptions. They certainly have enough experience.
Jim
Its not fear mongering… it’s actual facts and the reality of what will definitely happen in Japan anytime in the future! When this starts to happen then foreigners will all be lining up at the airports trying to escape Japan, whine and complain beyond believe! If you choose to live in a disaster prone country such as Japan than be prepared to lose your life at any moment! Living in Japan isn’t for the faint hearted so if you are nervous than leave while you still can!
Tatami53
"Volcanic ash is a fine, glassine substance," Shimamura pointed out. "People who normally wear contact lenses, for instance, would be advised to remove them, since friction from the ash can permanently damage their corneas."
I'm sorry, whaat? If Tokyo was covered in "volcanic ash," people would have a lot more to worry about than their "contact lenses."
Laguna
For sure is that Fuji will erupt again, and soon - but that "soon" is in geologic terms, meaning maybe next year, maybe in the next hundred, a blink in the eye of geology.
browny1
Euro dude - no fear mongering - just stating reality.
Recent examples include the Tohoku region where devastating tsunamis over history, told residents to build higher up. There are even historical markers in place to "never build below here".
A few generations passed and reality reared it's horrific force again.
Tokyo is the most ill-sited metropolis in the world.
Do we tremble with fear everyday - no! But that doesn't mean the inevitable won't happen.
It will happen in Kanto.
englisc aspyrgend
Japan is a volcanic island on the ring of fire, living with and planning for the inevitable eruptions and earthquakes should be standard procedure and anyone choosing to live there just has to accept the reality of their choice. Nothing in this world comes without a cost, there are no free lunches.
theFu
Coastal regions with Earthquakes, Tsunami, and volcanoes? Seems like a Darwin failure tri-fecta.
I love mountains (rock slide), volcanoes, and shoreline, but I won't live near any. There are enough other things trying to kill us, we don't need to make bad choices for where we live too.
As humans, we can look at historical data and use it to make wise choices. Be a human, not an extinct species.