The term supervolcano was first used in a TV documentary to describe eruptions of more than 1,000 cubic kilometres of magma. Such volcanoesare devastating, but very rare. The last one happened at Toba in Sumatra, Indonesia, 74,000 years ago.
The active volcanic system at Yellowstone National Park has resulted in super-eruptions – the most recent happened 640,000 years ago. Yellowstone’s volcanism is powered by magma rising from ahotspot. The relatively thick continental crust causes large amounts of magma to build up underground.