Supervolcanoes

SUPERVOLCANOESThe 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

VEIVolcanic

Explosivity Index

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 3VulcanianMontserrat

VEI 1 Hawaiian

VEI 6 Ultra-Plinian Mt Pinatubo

VEI 8 Imagine 100 Pinatubos erupting at the same time

Indonesia: Lake TobaUSA: Yellowstone National ParkUSA: Long Valley – CaliforniaNew Zealand: Lake TaupoUSA: Valles Caldera – New MexicoJapan: 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

http://www.youtube.com/watch?v=RRg3JUHCfhQ

Supervolcano !

Huge caldera, so big it could only be seen from space

There is a higher % of gas in the magmaThe magma comes from the Mantle (not subduction)A large volume of magma was ready to eruptLava is more viscousIncrease in frequency of earthquakes may open

fractures just above the chamberEruptions occur simultaneously from a ring of vents.

Why are supervolcano eruptions so big ?

http://www.cotf.edu/ete/movies/caldera.mov

earthmountainview.com

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

Possible Impacts

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 acrossDifferent from a crater

Supervolcanoes and

calderas !

E.g., Yellowstone, WY, 1 m.y.

Which type of volcano would you rather live beside and why?

Cinder coneStratovolcano(composite)Shield volcanoSupervolcano