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Supervolcanoes. The term " supervolcano " implies an eruption of magnitude 8 on the Volcano Explosivity Index, meaning that more than 1,000 cubic kilometers (240 cubic miles) of magma (partially molten rock) are erupted. S3 IHE GE 2014/Chan ML. VEI Volcanic Explosivity Index.
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Supervolcanoes The term "supervolcano" implies an eruption of magnitude 8 on the Volcano Explosivity Index, meaning that more than 1,000 cubic kilometers (240 cubic miles) of magma (partially molten rock) are erupted. S3 IHE GE 2014/Chan ML
VEIVolcanicExplosivityIndex http://volcanoes.usgs.gov/Imgs/Jpg/Photoglossary/VEIfigure.jpg
The Volcanic Explosivity Index- how big is a super-eruption ? VEI- 5 Plinian, Mt St Helens VEI 3 Vulcanian Montserrat VEI 1 Hawaiian
Indonesia: Lake Toba • USA: Yellowstone National Park • USA: Long Valley – California • New Zealand: Lake Taupo • USA: Valles Caldera – New Mexico • Japan: Aira Where are the Supervolcanoes?
The most recent such event on Earth occurred 74,000 years ago at the Toba Caldera in Sumatra, Indonesia.Which one will be next? http://www.youtube.com/watch?v=6GAxVSMwVYg&feature=related
Supervolcano ! http://www.youtube.com/watch?v=RRg3JUHCfhQ
There is a higher % of gas in the magma • The magma comes from the Mantle (not subduction) • A large volume of magma was ready to erupt • Lava is more viscous • Increase in frequency of earthquakes may open fractures just above the chamber • Eruptions occur simultaneously from a ring of vents. Why are supervolcano eruptions so big ? http://www.cotf.edu/ete/movies/caldera.mov
Possible Impacts • Regional effects: • falling ash would cover the surrounding states: Montana, Idaho and Wyoming • Thousands of death, homelessness, • Towns and cities would be instantly wiped out • Great impact to the economy • Calderas would be formed • Global effects: • changes to global climate • Devastation of world agriculture, disruption of food supplies • Mass starvation • Threat to millions of people around the world
E.g., Yellowstone, WY, 1 m.y. Supervolcanoes and calderas ! • Caldera - created from large, explosive eruptions of felsic pyroclastic material. The caldera is created when the roof of the magma chamber collapses. • Can be 10’s km’s across • Different from a crater
Which type of volcano would you rather live beside and why? Cinder cone Stratovolcano(composite) Shield volcano Supervolcano