Mechanisms of magmatic degassing and eruption triggering at Alaska volcanoes: experimental controls and natural system analogues

Abstract

Understanding the magmatic processes that drive volcanic eruptions is integral to monitoring volcanic unrest and mitigating the hazards that these systems pose on local communities, infrastructure, aviation, and maritime traffic. Variations in eruption style likely result from the complex interplay between bulk magma viscosity, magma ascent rate, and the efficiency of magma degassing/outgassing. The main goals of this dissertation will be to investigate parameters that influence eruption style and triggering through direct comparison of high pressure-temperature decompression experiments to natural system analogues, including well-studied systems in eastern California and a remote volcanic system in Alaska. The results of this study can be used to aid in more precise modeling of volcanic systems and assist in monitoring active volcanoes in Alaska, California, and worldwide. This thesis investigates eruption triggering dynamics by: 1) determining the extent to which crystals of varying size and shape influence degassing and outgassing kinetics in hydrous intermediate magmas from a purely experimental approach, 2) applying these results to analogue silicic lava domes in eastern California to investigate porosity-permeability relationships in some well-studied natural systems and use these results to form a first order model for post emplacement gas flux for these lava domes, and 3) investigating how magma mixing can trigger eruptions at Gareloi volcano, a frequently active yet poorly understood volcano in the western Aleutians, Alaska.