SHALLOW CONDUCTIVE-COMPONENT OF HEAT-FLOW NEAR NOVARUPTA DOME, KATMAI, ALASKA

An investigation of the shallow conductive heat flow from one of the half dozen thermal areas in the vicinity of Novarupta Dome suggests that convective heat transport by hydrothermal fluids is the dominant mode of heat transfer in the shallow subsurface within the thermal areas. The thermal observations are used to qualitatively characterize the state of the hydrothermal system at depth. We conclude that there is no shallow (100-200 m), laterally extensive heat source beneath the vent region but rather that the source of the heat emanating from the thermal areas is the cooling conduit that supplied magma to the surface during the 1912 eruption. This heat is transported to the surface by vapor flow along high permeability pathways associated with the margins of the 1912 vent. The thermal observations are also used to place a lower bound on the characteristic diameter of the conduit of 50 meters.