Supervolcanoes
Supervolcanoes or mega volcanoes produce monstrous explosions, far larger than Mt. St. Helens or Mt. Vesuvius or even Krakatau.Geologists have developed a scale to describe the size of a volcanic explosion; this is called the Volcanic Explosivity Index ( VEI).The index ranges from zero to 8. The table is taken from National Museum of Natural History — Smithsonian Institution Table 1.1: A table of VEI | VEI | Volume(km3) | Example | | 0 | Very Small | Masaya (Nicuargua),1570 | | 1 | >0.00001 | Poas (Costa Rica),1991 | | 2 | >0.001 | Ruapehu (New Zealand),1971 | | 3 | >0.01 | Nevado del Ruiz( Columbia), 1985 | | 4 | >0. 1 | Pelee (West Indies), 1902 | | 5 | >1 | Mount St. Helens(U.S.), 1980 | | 6 | >10 | Krakatau( Indonesia) 1883 | | 7 | >100 | Tambora( Indonesia) ,1815 | | 8 | >1000 | Toba (Sumatra) 73,500 years ago |
There have been many mega volcanoes during earth's history, but none during historical times. Some of the of the largest have occurred at Yellowstone in Wyoming,USA. There hasn’t been a monster explosion here for at least 600,000 years, but there is plenty of seismic and volcanic activity. In 1959 there was a powerful earthquake (7.8 on the Richter scale) a little west of the park. There followed landslides and abnormal behavior in geysers within the park.
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