Supervolcanoes: Not a Threat For 2012

The geological record holds clues that throughout Earth's 4.5-billion-year lifetime massive supervolcanoes, far larger than Mount St. Helens or Mount Pinatubo, have erupted. However, despite the claims of those who fear 2012, there’s no evidence that such a supereruption is imminent.

What exactly is a "supervolcano" or a "supereruption?" Both terms are fairly new and favored by the media more than scientists, but geologists have begun to use them in recent years to refer to explosive volcanic eruptions that eject about ten thousand times the quantity of magma and ash that Mount St. Helens, one of the most explosive eruptions in recent years, expelled.

It’s hard to comprehend an eruption of that scope, but Earth’s surface has preserved distinctive clues of many massive supereruptions. Expansive layers of ash blanket large portions of many continents. And huge hollowed-out calderas – craters that can be as big as 60 miles (100 km) across left when a volcano collapses after emptying its entire magma chamber at once – serve as visceral reminders of past supereruptions in Indonesia, New Zealand, the United States, and Chile.

The eruption of these prehistoric supervolcanoes has affected massive areas. The magma flow of Mount Toba in Sumutra, which erupted some 74,000 years ago in what was likely the largest eruption that has ever occurred, released a staggering 700 cubic miles (2,800 cubic km) of magma and left a thick layer of ash over all of South Asia. For comparison, the quantity of magma erupted from Indonesia’s Mount Krakatau in 1883, one of the largest eruptions in recorded history, was about 3 cubic miles (12 cubic km).