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Unformatted text preview: o add water (later, water makes it explosive) Volcanic rocks Dark Intermediate Light - basalt - andesite - rhyolite - low silica - int. silica - high silica - low viscosity - int. viscosity - high viscosity - low in gas - can be high in gas - mostly lava flow - mostly ash silica-SiO2 viscosity-stickiness/ease of flow -to get an explosive eruption need high viscosity and gas (H2O vapor) high viscosity and no gas = no explosive eruption low viscosity with gas = no explosive eruption low viscosity and no gas = no explosive eruption - most explosive volcanoes are located at subduction zones (because their magma has water vapor in it, and tend to have a higher viscosity)...
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This note was uploaded on 08/30/2010 for the course GEOL 105 taught by Professor Kohut during the Spring '08 term at University of Delaware.
- Spring '08