ERTH 2415 Lecture Notes - Lecture 10: Volcanic Plateau, Shield Volcano, Lava Dome
26 Apr 2016
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Document Summary
Most important mechanism: decrease pressure (p: decompression melting increase temperature (to increase water content. Phase change from solid to liquid accompanied by volume expansion. Hot, solid rock from asthenosphere rises closer to the surface. Decreaseinpressurecausesrocks to melt partiallydecompression melting: increase in volume induces fractures. More rocks liquefy: volatiles gradually come out of the melt. Gas bubbles push magma upward: magma fragments. Powerful gas jet expels magma in the atmosphere. Peaceful vs explosive: relation between: tectonic environment, magma composition, eruptive style. Caution: a volcano can change eruption type through time: relation between: eruptive style, eruption type, magma composition, volcanic landform. Factors controlling volcanism and volcanic landforms: viscosity2. Viscosity low/medium magma viscosity: volatiles low/medium volatile content, volume of magma small to large volume. Ectonic environments: divergent zone hot spot: magma composition: basaltic. Low viscosity: lava flows like water: low volatile content: volatiles escape easily, small volume landform: lava plateau.
