Thermal observations of degassing open conduits and fumaroles at Stromboli and Vulcano using remotely sensed data

For volcanoes characterised by activity from open degassing conduits and fumarole fields, thermal data from remote sensing instruments can provide an integrated data set capable of measuring various volcanic system parameters (e.g., magma depth, thermal flux and vent areas) and of mapping the distribution of vents and other thermal features. At Stromboli such thermal data define a persistent vent system aligned along a SE-NE tectonic line, fed by a shallow (< 1 km deep) magma chamber. Total thermal losses from the conduit between the magma surface and vent are ~ 4 MW for high-temperature degassing vents, and ~ 14 MW for all vents within the crater terrace. At Vulcano, heat from a < 4 km deep magma body drives a hydrothermal system feeding a 400–470 m2 exhalative area. Consistent thermal flux measurements at Vulcano (38.6 ± 2 W m−2) between 1985 and 1995 are validated by detailed ground measurements. Time series constructed from repeated satellite and aircraft over-passes are capable of monitoring fluctuations in activity. At Stromboli, a time-series constructed for 1985 to 1995 distinguishes phases of intense explosive, lava pond and effusive activity. At Vulcano, a steady level of activity is identified over the same period. The good agreement with ground data suggests that the techniques presented here could be used at other volcanoes characterised by open conduit or fumarolic activity, either when no other data sources are available, or as a reliable supplement to more traditional data sources (e.g., seismic and chemical analyses).