• volcanic degassing;
  • volcanic gases;
  • Etna

[1] The Total Volatile (TV) flux from Mount Etna volcano has been characterised for the first time, by summing the simultaneously-evaluated fluxes of the three main volcanogenic volatiles: H2O, CO2 and SO2. SO2 flux was determined by routine DOAS traverse measurements, while H2O and CO2 were evaluated by scaling MultiGAS-sensed H2O/SO2 and CO2/SO2 plume ratios to the UV-sensed SO2 flux. The time-averaged TV flux from Etna is evaluated at ∼21,000 t·day−1, with a large fraction accounted for by H2O (∼13,000 t·day−1). H2O dominates (≥70%) the volatile budget during syn-eruptive degassing, while CO2 and H2O contribute equally to the TV flux during passive degassing. The CO2 flux was observed to be particularly high prior to the 2006 eruption, suggesting that this parameter is a good candidate for eruption prediction at basaltic volcanoes.