Wednesday 26 January 2011

The Toba SuperVolcano


Everybody knows about yellowstone and the supervolcano below its surface but what is not being looked into is the other supervolcanos all over our planet especially the Toba About 75,000 years ago, this Indonesian volcano released about 2,800 km3 DRE of ejecta, the largest known eruption within the Quaternary Period (last 1.8 million years) and probably the largest explosive eruption within the last 25 million years. In the late 1990s, anthropologist Stanley Ambrose[1] proposed that a volcanic winter induced by this eruption reduced the human population to about 2,000 - 20,000 individuals, ody resulting in a population bottleneck (see Toba catastrophe theory). More recently several geneticists, including Lynn Jorde and Henry Harpending have proposed that the human race was reduced to approximately five to ten thousand people.[2] Whichever figure is right, the fact remains that the human race seemingly came close to extinction about 75,000 years ago.

Eruptions forming even larger calderas are known, especially La Garita Caldera in the San Juan Mountains of Colorado, where the 5,000 km3 Fish Canyon Tuff was blasted out in a major single eruption about 27.8 million years ago.

At some points in geological time, rhyolitic calderas have appeared in distinct clusters. The remnants of such clusters may be found in places such as the San Juan Mountains of Colorado (erupted during the Tertiary Period) or the Saint Francois Mountain Range of Missouri (erupted during the Proterozoic).

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