EARTHSC 1G03 Lecture 10: 1GO3 lecture 10 volcanoes F13.pdf
29 Oct 2014
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Liquefaction transformation of saturated sediment or soil to liquid when ground shaking causes particles to lose contact. Liquefaction of soil in niigata, japan caused earthquake- resistant buildings to fall over. Begin to slow and rise as they "touch bottom" Water pulls back from shorelines before tsunami arrives. Date-time: sunday dec. 26, 2004 at 07:58:53 am local time. Date-time: monday march 28, 2005 at 11:09:36 am local time. Shield volcano low silica content low viscosity, runny lava placid eruptions rhyolite / andesite basalt. Violent eruptions (left) result from gas bildup due to stiff, viscous, high-silica magmas - rhyolitic. Cone shape results from debris that falls out near vent of volcano. Composite volcano high silica content stiff, viscous lava highly explosive. Shield volcano low silica content low viscosity, runny lava placid eruptions rhyolite / andesite. Gas content and magma viscosity important controls on eruption style: More placid eruptions (right) occur in low viscosity, silica-poor magmas, such as basalt.
