ICE MELT RATES IN LIQUID-FILLED CAVITIES DURING SUBGLACIAL EXPLOSIVE ERUPTIONS
Calculations of heat flux from ice cavity liquid water to the melting ice surface indicate that up to 0.6 MW m-2 can be obtained for single phase free convection. Our model of boiling two-phase free convection in subglacial cavities indicates that heat fluxes in the range 3-5 MW m-2 can be obtained in the vent region of the cavity and may be increased further by momentum transfer from the eruption jet. Rapid heat transfer to water from fragmented magma is needed to sustain these heat fluxes. Such heat fluxes approach those required to explain jökulhlaup flow rates and rapid ice penetration by melting in the Gjálp 1996 eruption.