Modelling glaciovolcanic caves and chimneys

A fifth of Earth's volcanoes are covered by snow and/or ice and many have active geothermal systems that interact with the overlying ice. These glaciovolcanic interactions can melt voids into glaciers, and are subject to controls exerted by ice dynamics and geothermal heat output. Glaciovolcanic voids have been observed to form prior to volcanic eruptions, which raised concerns when such features were discovered within Job Glacier in the Mount Meager Volcanic Complex, British Columbia, Canada. In this thesis I model the formation, evolution, and steady state existence of glaciovolcanic voids, using analytical and numerical models. Steady state void geometries are derived, and numerical model results suggest that the square of glaciovolcanic void height scales linearly with geothermal heat flux, and inversely with the n-th power of glacier thickness, where n is the ice flow law exponent. Finally, the established relationships between glaciological and geothermal parameters are applied to the glaciovolcanic voids within Job Glacier, suggesting 0.5-5 MW subglacial geothermal heat sources.