Earth Sciences 2240F/G Lecture Notes - Lecture 8: Blow Torch, Stratovolcano, North American Plate
17 Dec 2017
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Document Summary
The largest eruptions come from giant resurgent calderas, which normal form over the tops of mantle plumes that pierce continents. Any magma erupts when it gets so close to surface the overlying pressure of the load of rock over it is less than the volatile pressure within it. The explosion will only be explosive if: the magma is highly viscous, the magma has a high content of exsolved volatiles, the cork or cap on the volcanic conduit suddenly ruptures. When magma reaches about 2km from the surface eruption is inevitable: at this point the pressure of overlying rock will become less than the pressure within the magma for most magma that has high silica/volatile composition. Plinian eruptions, named for a father/son pair that drew sketches of the eruption of. Mount vesuvius in 79ad, these eruptions go straight up. Eruptions that blow from the side aka the weakest area on the volcano are called pelean eruptions.
