For Yellowstone, that type of supereruption
last happened more than 600,000 years ago, after magma filled the empty chambers below the Earth's surface some decades before it blew.
Giant blobs of magma appear underground and then pour onto the surface within centuries, suggests a new study of a California supereruption.
Yellowstone, for one, underwent its most recent supereruption about 640,000 years ago.
For example, he sees the supereruption
of Mount Toba as nearly wiping out humans.
Fortunately, there is no large-scale ground deformation or greatly increased seismic or geyser activity that signals an impending supereruption.
Although there is no proven link between the Lake Toba supereruption and the genetic bottleneck, the close association in time may not be coincidental.
When the magma shot out during the last supereruption, it left a void under the volcano's "roof" and the top caved in.
Lisa Morgan, a research geologist for the United States Geological Survey, doesn't think a supereruption will occur for tens of thousands of years.
However, despite the claims of those who fear 2012, there's no evidence that such a supereruption
A team of researchers headed by ETH-Zurich professor Carmen Sanchez-Valle has now identified a trigger for supereruptions
by determining the density of supervolcanic magma, using an X-ray beam at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.
2008: "Snake River (SR)-type" volcanism at the Yellowstone hotspot track: distinctive products from unusual, high-temperature silicic supereruptions
Short of a meteor impact, these supereruptions
are the worst environmental hazards our planet can face,' Gregg said.