<P> A supervolcano is a large volcano that has had an eruption of magnitude 8, which is the largest value on the Volcanic Explosivity Index (VEI). This means the volume of deposits for that eruption is greater than 1,000 cubic kilometers (240 cubic miles). A supervolcanic eruption may be a single short - term event or a massive outpouring of lava lasting up to millions of years . </P> <P> Supervolcanoes occur when magma in the mantle rises into the crust but is unable to break through it and pressure builds in a large and growing magma pool until the crust is unable to contain the pressure . This can occur at hotspots (for example, Yellowstone Caldera) or at subduction zones (for example, Toba). Another setting for the eruption of very large amounts of volcanic material is in large igneous provinces, which can cover huge areas with lava and volcanic ash, causing long - lasting climate change (such as the triggering of a small ice age), which can threaten species with extinction . The Oruanui eruption of New Zealand's Taupo Volcano (about 26,500 years ago) was the world's most recent super eruption at a VEI - 8 eruption . </P> <P> The origin of the term "supervolcano" is linked to an early 20th - century scientific debate about the geological history and features of the Three Sisters volcanic region of Oregon in the United States . In 1925, Edwin T. Hodge suggested that a very large volcano, which he named Mount Multnomah, had existed in that region . He believed that several peaks in the Three Sisters area are the remnants of Mount Multnomah after it had been largely destroyed by violent volcanic explosions, similar to Mount Mazama . In 1948, the possible existence of Mount Multnomah was ignored by volcanologist Howel Williams in his book The Ancient Volcanoes of Oregon . The book was reviewed in 1949 by another volcanologist, F.M. Byers Jr . In the review, Byers refers to Mount Multnomah as a supervolcano . Although Hodge's suggestion that Mount Multnomah is a supervolcano was rejected long ago, the term supervolcano was popularised by the BBC popular science television program Horizon in 2000 to refer to eruptions that produce extremely large amounts of ejecta . </P> <P> The term megacaldera is sometimes used for caldera supervolcanoes, such as the Blake River Megacaldera Complex in the Abitibi greenstone belt of Ontario and Quebec, Canada . Eruptions that rate VEI 8 are termed "super eruptions ." Though there is no well - defined minimum explosive size for a "supervolcano", there are at least two types of volcanic eruptions that have been identified as supervolcanoes: large igneous provinces and massive eruptions . </P>

What are the super volcanoes in the world