Documentary Description
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.
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