This
morning, when I watched the video about the collapse tunnel alarm
bells went off for me when I read that the 5-km- long tunnel went
under the hills leading to Mt Fuji.
There
have been warnings going back to September that pressure in the magma
chamber of Mt Fuji was at a level higher than when it last erupted
300 years ago.
Now
comes the warning.
Experts
warn dangerous build-up of magma occurring at many of Japan’s 110
active volcanoes
Japan
should brace for a catastrophic volcanic eruption at some point, say
experts, citing a massive buildup of magma at many of the nation's
110 active volcanoes.
3
December, 2012
The
last particularly serious eruption in Japan occurred in 1914, when
Mount Sakurajima in southern Kagoshima Prefecture blew its top.
According
to study by volcanologists, Japan, which lies on the Pacific Rim of
Fire, has been shaken by more than 1,000 volcanic eruptions over the
past 2,000 years.
"The
possibility of a major eruption in the future is real," said
Yoichi Nakamura, a professor of volcanology at Utsunomiya University
who has been analyzing volcanic eruptions with a team of researchers.
To
be classified as active, a volcano must have erupted within the past
10,000 years or still be spewing gases, according to the Japan
Meteorological Agency.
The
active volcanoes include sites in the disputed Northern Territories
off northeastern Hokkaido as well as undersea volcanoes.
Of
the 110 active volcanoes, the agency monitors activity of the 47
around the clock to detect signs of an imminent eruption.
When
offshore Mount Sakurajima erupted, it spewed out so much lava that it
created a land bridge with the Osumi Peninsula. Volcanic ash even
fell on eastern Japan.
The
researchers said seismic activity surged at 20 active volcanoes
around Japan, including Mount Fuji, after the magnitude-9.0 Great
East Japan Earthquake struck last year.
It
was one of the most powerful earthquakes on record. It struck with
such force that the Japanese land mass shifted.
Over
the past century, volcanic eruptions around the world were apparently
triggered by magnitude-9.0 or stronger earthquakes that struck
several years earlier.
Nakamura
also is involved with the nonprofit Vocanological Society of Japan.
He said the study was intended to help local officials prepare for a
contingency resulting from a major eruption by assessing the risks
posed by volcanoes around the country.
Particularly
worrisome, he said, was a lack of data pointing to a reduction in
magma. In the absence of a really huge eruption for a century
suggested there was a massive buildup of magma, which at some point
will inevitably spew from a volcano with tremendous force.
According
to the study, 1,162 eruptions have occurred in Japan over the past
2,000 years. Of these, 52 were major events that spewed a massive
volume of ash and lava over a short period. It amounts to a
large-scale eruption occurring every 38 years.
Records
show that three volcanic eruptions in the 17th century, including one
at Mount Hokkaido-Komagadake in Hokkaido in 1640, spewed out the
equivalent of 1 billion cubic meters of ash and lava.
Two
similar eruptions occurred in the 18th century, one of which involved
Mount Fuji in 1707.
The
study showed that relatively large eruptions occurred 124 times.
There
were 562 instances of medium-scale eruptions, or one every 3.6 years.
These
included the eruption of Mount Unzen-Fugendake in Nagasaki Prefecture
in 1991 and the eruption of Mount Usuzan in Hokkaido in 2000.
Of
the 1,162 eruptions, the 47 volcanoes consistently monitored by the
Japan Meteorological Agency represent nearly 90 percent of the
activity, or 1,012 of those events.
Mount
Aso in Kumamoto Prefecture is the most active volcano with 167
recorded eruptions, followed by Mount Asama straddling Nagano and
Gunma prefectures, at 124; Mount Sakurajima, at 91; Mount Izu-Oshima
in Tokyo, at 77; and Mount Kirishima straddling Kagoshima and
Miyazaki prefectures, at 70.
Mount
Fuji has erupted 38 times.
Here
is the video about the tunnel collapse
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