Temperature and Area Constraints of the South Volund Volcano on IO from the NIMS and SSI instruments during the Galileo G1 OrbitAnalysis of data from darkside and eclipse observations of Io by the NIMS and SSI instruments show that the South Volund hot spot is a manifestation of high temperature active silicate volcanism. The NIMS data are fitted with a two temperature model (developed from modelling terrestrial lavas) which yields a better fit to the data than a single temperature fit.