I was just watching the French version of Horizon. Today's program was about supervolcanoes. These explode with many many times the energy of the Katmai eruption and basically affect the planet on a scale comparable to an asteroid impact. The problem is that volcanoes cannot be diverted somewhere else into space.
The last such supervolcano to erupt was Toba in Sumatra about 74000 years ago. It erupted with about 10,000 times the strength of St. Helens. One interesting coincidence is that this time frame corresponds with a recently discovered genetic bottleneck in human diversity. People in the current human population are genetically much closer than they should be. It appears that some catastrophe in the recent past greatly reduced world population so that only a few thousand families survived to repopulate the Earth. The use of the controversial maternal mitochondrial DNA mutation clock appears to pinpoint that bottleneck at 70,000-80,000 years ago, about the time of the Toba eruption. That the bottleneck occurred is no longer controversial, only its date.
One dormant supervolcano lies under Yellowstone Park. It is 40,000 years past the normal date in its 600,000 years eruptive cycle. To give you an idea, if a major earthquake broke the thin crust above it (only 8km there), the pressure release (what cause the bang at Mount St. Helens) would blow up the top and hurl magma (now lava) 30-40km high. Everything would be incinerated within a diameter of 1000 km, etc...
Rather scary. And it will happen some day.
http://www.bbc.co.uk/horizon/supervolcanoes_script.shtml
http://www.bbc.co.uk/horizon/supervolcanoes.shtml
http://news.bbc.co.uk/low/english/sci/tech/newsid_628000/628515.stm
http://www.yellowstoneonline.com/yellowstoneonline/html/caldera.html
A Thing Of The Past (The Tweeds)
The last such supervolcano to erupt was Toba in Sumatra about 74000 years ago. It erupted with about 10,000 times the strength of St. Helens. One interesting coincidence is that this time frame corresponds with a recently discovered genetic bottleneck in human diversity. People in the current human population are genetically much closer than they should be. It appears that some catastrophe in the recent past greatly reduced world population so that only a few thousand families survived to repopulate the Earth. The use of the controversial maternal mitochondrial DNA mutation clock appears to pinpoint that bottleneck at 70,000-80,000 years ago, about the time of the Toba eruption. That the bottleneck occurred is no longer controversial, only its date.
One dormant supervolcano lies under Yellowstone Park. It is 40,000 years past the normal date in its 600,000 years eruptive cycle. To give you an idea, if a major earthquake broke the thin crust above it (only 8km there), the pressure release (what cause the bang at Mount St. Helens) would blow up the top and hurl magma (now lava) 30-40km high. Everything would be incinerated within a diameter of 1000 km, etc...
Rather scary. And it will happen some day.
http://www.bbc.co.uk/horizon/supervolcanoes_script.shtml
http://www.bbc.co.uk/horizon/supervolcanoes.shtml
http://news.bbc.co.uk/low/english/sci/tech/newsid_628000/628515.stm
http://www.yellowstoneonline.com/yellowstoneonline/html/caldera.html
A Thing Of The Past (The Tweeds)
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