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Unformatted text preview: * Lava fountains, no more than a couple hundred feet in the air *Can flow at high speeds (30mph)-The volcano Explosivity Index (VEI) ranks volcanoes by the amount of magma erupted *0-2 very small chambers, not very dangerous eruptions, basalt eruptions *7-8 very dangerous, Felsic eruptions (andesite and rhyolite) *VEI is related water content and viscosity, which are controlled by magma composition *VEI and eruption type correlate to magma composition, magma chamber depth, and time between eruptions -Calderas form when very large magma chambers empty and collapse *EX. Crater Lake, Oregon *Yellowstone National Park is an excellent example of a collapsed caldera *3 cycles of Yellowstone eruptions began 2.2 million years ago and ended 600,000 years ago. Magma is still present below the park at 15 km depth *The Yellowstone caldera continues to show tectonic and hydrothermal activity...
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This note was uploaded on 08/09/2011 for the course GEOS 1004 at Virginia Tech.