Supervolcanoes
Hidden deep beneath the Earth's surface lie one of the most destructive and
yet least-understood natural phenomena in the world - supervolcanoes.
Only a handful exist in the world but when one erupts it will be unlike
any volcano we have ever witnessed. The explosion will be heard around
the world. The sky will darken, black rain will fall, and the Earth
will be plunged into the equivalent of a nuclear winter.
Normal volcanoes are formed by a column of magma - molten rock - rising from deep within the Earth, erupting on the surface, and hardening in layers down the
sides. This forms the familiar cone shaped mountain we associate with
volcanoes. Supervolcanoes, however, begin life when magma rises from
the mantle to create a boiling reservoir in the Earth's crust. This
chamber increases to an enormous size, building up colossal pressure
until it finally erupts.
The last supervolcano to erupt was Toba 74,000 years ago in Sumatra. Ten
thousand times bigger than Mt St Helens, it created a global
catastrophe dramatically affecting life on Earth. Scientists know that
another one is due - they just don't know when... or where.
It is little known that lying underneath one of America's areas of
outstanding natural beauty - Yellowstone Park - is one of the largest
supervolcanoes in the world. Scientists have revealed that it has been
on a regular eruption cycle of 600,000 years. The last eruption was
640,000 years ago... so the next is overdue.
And the sleeping giant is breathing: volcanologists have been tracking the
movement of magma under the park and have calculated that in parts of
Yellowstone the ground has risen over seventy centimetres this century.
Is this just the harmless movement of lava, flowing from one part of
the reservoir to another? Or does it presage something much more
sinister, a pressurised build-up of molten lava?
Scientists have very few answers, but they do know that the impact of a Yellowstone
eruption is terrifying to comprehend. Huge areas of the USA would be
destroyed, the US economy would probably collapse, and thousands might
die.
And it would devastate the planet. Climatologists now know that Toba
blasted so much ash and sulphur dioxide into the stratosphere that it
blocked out the sun, causing the Earth's temperature to plummet. Some
geneticists now believe that this had a catastrophic effect on human
life, possibly reducing the population on Earth to just a few thousand
people. Mankind was pushed to the edge of extinction... and it could
happen again.
Heres the satalite pic of the volcanic dust
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