The Soufriere Crater Lake as a calorimeter

Abstract

IN 1971–72, 8 × 10⁷m³ of basaltic andesite lava were extruded into the summit crater of Soufriere volcano, St Vincent¹. The first half of the eruption took place entirely subaqueously and the second half almost entirely so and these facts have provided us with an unusual opportunity to carry out quantitative studies of several aspects of the eruption. Before the eruption the crater contained 7.5 × 10⁷m³ of water and the potential of this lake as a giant condenser of volcanic gases has already been demonstrated². We show here that by treating the crater lake as a giant calorimeter we can make reasonably accurate estimates of the rate at which heat was lost by the erupted lava and hence draw important conclusions about its mode of extrusion. The heat transfer data are consistent with the idea that the lava mass accumulated by the multiple extrusion of numerous small lava bodies¹ rather than by extrusion of a single domelike mass, as has been proposed by other workers^{3, 4}.