EAR 105 Lecture Notes - Lecture 11: Andesite, Air Hockey, North American Plate
17 Oct 2016
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Document Summary
Volcanic gases - expelled vapor and aerosols. Pyroclastic debris - fragments blown out of a volcano. Lava flows - molten rock that moves over the ground. Philippines had a big eruption in the 90s, associated with subduction zone. Builds the surface of the sea floor. Magma pokes through the continent > part of africa pulling away from the main continent. The yellowstone hot spot burned a track into the overriding north american plate. The shape of the volcano says something about the kind of lava. The volcano shape is controlled by the properties of the lava. The properties of the lava are controlled by the chemistry. Viscosity (resistance to flow) = think of honey, not water. Basaltic lava has low viscosity and can flow long distances. Andesitic lava is too viscous to flow far and tends to break up as it flows. Felsic lava is so viscous that it may pile up in a dome-shaped mass.
