'Supervolcano' forming near New Zealand, Feb. 13, 2013 (stuff.co.nz) A "supervolcano" forming deep below the Earth's crust north of New Zealand, will have the power to destroy the world, but scientists are urging people not to worry - it could be 100 million years away. The study has found that deep beneath the Pacific Ocean, near Samoa, two or more continent-sized piles of rock were colliding as they moved at the bottom of Earth's thick mantle and atop the thicker core. High resolution seismic imaging showed an ongoing collision between the piles of rock was merging in a "spongy blob of partly molten rock" underneath the volcanically active hotspot.
Wikiedia: 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, U.S.A. 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 left after Mount Multnomah 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 volcano scientist, 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. That program introduced the subject of large-scale volcanic eruptions to the general public.
Volcanologists and geologists do not refer to "supervolcanoes" in their scientific work, since this is a blanket term that can be applied to a number of different geological conditions. Since 2000, however, the term has been used by professionals when presenting to the public. 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".