An active volcano on Jupiter’s satellite Io, at −19° lat., 255° W long. It lies in a volcanic complex about 500 km across, which includes lava flows and tablelands. It was active in 1979 March during the Voyager 1 encounter, but had ceased by the time Voyager 2 passed four months later. In 1996 it was seen by the Hubble Space Telescope to generate a plume over 400 km high in the course of a few tens of hours. Vaporized sulphur might be responsible for eruptions of this size, the heat being provided by an intrusion of molten silicate magma.