A supervolcano is any volcano capable of producing a volcanic eruption with an ejecta volume greater than 1,000 km3 (240 cu mi). This is thousands of times larger than normal volcanic eruptions.
Supervolcanoes can occur either when magma in the mantle rises into the crust from a hotspot but is unable to break through the crust, thus pressure builds in a large and growing magma pool until the crust is unable to contain the pressure (this is the case for the Yellowstone Caldera), but they can also form at convergent plate boundaries (for example, Toba).
Although there are only a handful of Quaternary supervolcanoes, supervolcanic eruptions typically cover huge areas with lava and volcanic ash and cause a long-lasting change to weather (such as the triggering of a small ice age) sufficient to threaten species with extinction.
http://en.wikipedia.org/wiki/Supervolcano
This “supervolcano” averages one of its eruptions every 600,000 years. It’s now been 640,000 years since the last one.
The Yellowstone Supervolcano: New Finding —”Potential to Erupt With 2,000 Times the Force of Mount St. Helens”
A new study by the University of Utah revealed that the hot molten rock beneath Yellowstone National Park is 2 ½ times larger than previously estimated, meaning the park’s supervolcano has the potential to erupt with a force about 2,000 times the size of Mount St. Helens. By measuring seismic waves from earthquakes, scientists were able to map the magma chamber underneath the Yellowstone caldera as 55 miles long, lead author Jamie Farrell of the University of Utah said after presenting his findings last week to the American Geophysical Union. The last Yellowstone eruption happened 640,000 years ago, according to the U.S. Geological Survey.
The chamber is 18 miles wide and runs at depths from 3 to 9 miles below the earth, he added. That means there is enough volcanic material below the surface to match the largest of the supervolcano’s three eruptions over the last 2.1 million years, Farrell said. The largest blast — the volcano’s first — was 2,000 times the size of the 1980 eruption of Mount St. Helens in Washington state. The USGS’ Yellowstone Volcano Observatory listed the park’s volcano alert level as “normal” for December.
Some scientists tracking earthquake swarms under Yellowstone have warned the caldera is overdue to erupt. Farrell dismissed that notion, saying there isn’t enough data to estimate the timing of the next eruption. “We do believe there will be another eruption, we just don’t know when.” A large earthquake at Yellowstone is much more likely than a volcano eruption, Farrell added. The 7.5-magnitude Hebgen Lake earthquake killed 28 people there in 1959.
Some 640,000 years ago there was a colossal cauldron of magma, a supervolcano, that exploded with such violence that it left an ash layer almost ten feet deep a thousand miles away in eastern Nebraska killing all plant life and covering almost all of the United States west of the Mississippi. Modern geological surveys have shown that this supervolcano erupts catastrophically every 600,000 years. The land that supervolcano is trapped in was called by Blackfoot Indians ‘the land of evil spirits’ -what we know today as Yellowstone National Park.
See much more at the link ...
You better move....after you go to bed...
Last caldera forming eruption was a minor one that formed west thumb caldera in Yellowstone lake “174,000” years before present.
A minor eruption.
Probably one of several that precede a large eruption.
Yawn... Yellowstone is always moving. The whole basin breaths, so what’s the big deal about a 3.x?
Nothing.
If the Yellowstone super volcano blows, say good bye to the US and large parts of the world as the cloud of ash could seriously affect climate around the world.
To make it more scarier it should be called megavolcano.
Ping-a-ling