ERTH 2415 Lecture 10: ERTH 2415 - CLASS 10
7 Oct 2016
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Erth 2415 class 10: eruptive style and landforms i. Volcanoes are a mechanism by which earth expels internal heat quickly. The most important mechanism that causes solid rock to melt is the mechanism that decreases pressure (p). Most important mechanism: decrease pressure (p: decompression melting. Phase changes from solid to liquid accompanied by volume expansion. Volcanic eruption step-by-step: hot, solid rock from asthenosphere rises closer to the surface. Decrease in pressure causes rocks to melt partially (decompression melting) Fractures create pathways through which more hot material rises. More rocks liquefy: volatiles gradually come out of the melt. Gas bubbles push magma upwards: magma fragments. When bubbles > 75% magma volume powerful gas jet expels magma in the atmosphere. There are two eruptive styles: peaceful vs explosive. There is a relationship between tectonic environment, magma composition, and eruptive style. Eruption type there are 6 types of eruptions a volcano can change eruption type through time.
