Atmospheric dispersion of natural gases at Vulcano island

Various computational scenarios are analyzed for the evaluation of volcanic CO2 and SO2 concentrations in the air over the island of Vulcano (Aeolian Archipelago, north of Sicily). Simulations were done using a 3D mesoscale meteorological model for complex terrain. Local wind depends on differences in land heating and cooling and on island topography. Row model outputs were used by a Lagrangian particle model to simulate dispersion of gases emitted from crater fumaroles. Both models were able to reproduce observations. Simulation of the fumarolic gas dispersion at Vulcano were performed for selected summertime conditions, when more than 10,000 tourists reside in the area of Vulcano Porto. In the inhabited area NW of the cone, the highest concentrations of gases occur near sunrise, due to nocturnal stratification and downslope breezes from the volcano. Present gas emission rates from crater fumaroles do not pose any hazard for humans. An SO2 output rate two orders of magnitude higher with respect to a considered case of 30 tons per day may pose an hazard.