Volcanos a bigger threat than comets
ABCONLINE 20/7/2002
A volcanic super-eruption could pose twice as much of a threat to civilisation as a
collision with an asteroid or comet.
Every 100,000 years, a cosmic body with a diameter of more than one kilometre slams into
the Earth but Michael Rampino, of New York University, warned that a massive volcanic
eruption capable of causing as much devastation occurs once every 50,000 years.
"Volcanoes in Yellowstone Park and Long Valley in California have erupted three times
in the past 1 million years, each time coating the whole of the US with ash," New
Scientist magazine said.
"But the biggest and most recent super-eruption happened at Toba, on the island of
Sumatra, 73,000 years ago."
According to Mr Rampino's research, Toba blasted a crater 100 kilometre long and sent 3
billion tonnes of sulphur dioxide into the atmosphere and a dense volcanic cloud around
the globe.
"He also suspects that Toba's super-eruption was responsible for the population crash
of 70,000 years ago, when the number of people fell to no more than 10,000," the
magazine added.
Ash and aerosols from super-eruptions block the sun and send global temperatures
plummeting.
Another Toba super-eruption could push temperatures down and cause regional cooling,
according to Mr Rampino.
"That's going to kill off most of the above-ground vegetation in Africa," he
said, adding global vegetation could be reduced by 25 per cent.END OF REPORT
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