EOSC 114 Chapter Notes - Chapter Ch 6: Strombolian Eruption, Lava Dome, Pumice
22 Mar 2016
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Plinian erupion: blows ash and volcanic gases to great heights. Lahars: gravity pulled mass movement of muddy volcanic debris. Subducion zone volcanoes are explosive and dangerous (remember where subducion happens). Oxygen and silicon most abundant in earth"s crust. Rock types based on si and o (sio2) %s. o o. Plutonic rock: magma cools and solidiies below surface. 3 types of magna: basalt, andesite, rhyolite. o. Water content is controlling role and viscosity is secondary role in determining peaceful vs explosive type of erupion. In magma water is most abundant dissolved gas. It lowers meling point of rock which parially liqueies and moves upwards. As it moves up, pressure decreases, water dissolved in hot magma becomes gas and forms steam which makes erupions powerful. Rhyoliic magma: dissolved water content up to 6%. As steam form, they have hard ime geing out of high viscosity magma and have to burst their way out. Mainly formed from light-colored minerals last to crystallize.
