Japan – Underwater supervolcano stirring to life

A giant lava bubble is expanding at Kikai volcano, a supervolcano just 31 miles south of Japan’s main island of Kyushu.

More than 31 cubic kilometers (7.4 cubic miles) of lava have shoved the seabed up around 2,000 feet, creating a giant dome with a diameter of about six miles.

The rising dome, with its peak is now less than 100 feet (30 m) below the ocean’s surface, is estimated to contain a much more immense volume of lava than the Yellowstone or Long Valley calderas.


The area also contains active hydrothermal springs and dense streams of gas bubbling up from the sea bed.

“The most serious problem that we are worrying about is not an eruption of this lava dome, but the occurrence of the next supereruption,” said Yoshiyuki Tatsumi a volcanologist at Kobe University in Japan and lead author of the new study published in Nature Scientific Reports.

Dr. Tatsumi thinks the chances of a supereruption in the within the next 100 years are only about 1 percent. But when that eruption comes, it could eject nearly 10 cubic miles of magma (not ash, but magma!), enough to cover almost all of Japan in ash nearly eight inches thick, he found.

Researchers say such an eruption could kill some 100 million people who live within its fallout zone, which includes the cities of Nagasaki, Hiroshima and Osaka.

Such an eruption would also have a serious effect on global climate. Temperatures would plunge and crops would fail.

Kikai has exploded catastrophically before. Japanese volcanologists have found evidence of an eruption of 500 cubic kilometres (120 cubic miles!) of magma some 7,300 years ago (the Akahoya eruption), another about 95,000 years ago, and yet another about 140,000 years ago.

(Look at this graph on one of my previous posts: Temperatures plummeted about 7,300 years ago.)

“The post-caldera activity is regarded as the preparation stage to the next super-eruption,” Tatsumi told Live Science, “not as the calming-down stage from the previous super-eruption.”

See video:




Although you may not have heard of it before, Kikai is already considered an active volcano. Minor eruptions occur frequently on Mount Iō on the island of Iōjima, which lies on the caldera rim.

The most recent eruptions occurred in 2001, 1982, 1980, 1978, 1976, 1974?, 1969?, 1967, 1957 and 1943.

Kikai Caldera was the source of the Akahoya eruption, one of the largest eruptions during the last twelve thousand years.


Thanks to Laurel and several others for these links


6 thoughts on “Japan – Underwater supervolcano stirring to life”

  1. Iōjima (Kagoshima)
    From Wikipedia, the free encyclopedia
    Not to be confused with Iwo Jima, an island with World War II historical significance.

    Just what the world needs. One more super volcano except this one is rated as a VEI 7. Not the end of the world but if you get enough of these erupting it will make a difference.

  2. If one takes all the odds calculates for super volcanoes exploding, what the odds are one of them blows this century.

  3. In looking at the dip between the two Sahara Warm periods, it look as if the fist dip down stabilised around a two hundred year cool period perhaps during two paired GSM similar to Spoorer or Maunder, which because of the disturbed orbit around the Solar System BarryCentre generated sufficient gravity waves to kick off volcanic eruptions of this magnitude.
    The LALIA had three major eruptions; both Spoorer and Maunder had significant eruptions to take place in conjunction with the GSM.

  4. The Dalton minimum had Soufriere erupt in the Carribean in 1812, Mayon in the Philippines in 1814 and Tambora in Indonesia in 1815. The last of course caused “the year without summer” in Europe and Nth. America.

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