EOSC 114 Lecture Notes - Lecture 12: Vesicular Texture, Vulcanian Eruption, Strombolian Eruption

• School: UBC
• Department: Earth and Ocean Sciences
• Course: EOSC 114
• Professor: Brett Gilley

Document Summary

Volume change driven by bubbles is the key. Bubbles escape with low viscosity, cannot escape in high viscosity. 2. bubbles expand as the magma rises (lower p) Depends on amount of bubbles, rate of rise, bubble retention. Viscosity and gas content are very important in determining the eruption style. As magma rises-->pressure decreases-->bubbles begin to form. Pressure rises inside the bubbles until the strength of the liquid magma is overcome-- Density plays the least important role in explosivity. Bubbles grow with difficulty in highly viscous magma, therefore high viscosity promotes high explosivity. External water adds to explosivity because of the rapid heating of water. Describes the size of an explosive volcanic eruption. Mainly depends on total volume erupted explosively. 1 unit increase= 10 times more volume erupted. Angle of repose (30 to 40 degrees) Usually erupt for a few years then never again. Lava erupts from fissure, runs down gentle slopes, cooling.