Developments in real-time radon monitoring at Stromboli volcano

We present the results of one year of continuous radon monitoring at Stromboli volcano collected at two automated real-time stations. These were deployed on the NE flank (at 520 m a.s.l.) and within the summit area (900 m a.s.l.). Higher daily emissions at the lower station approached 4,200 Bq/m3, with bulk averages around 1,800 (±980) Bq/m3; whereas the summit station reached peak values of 23,000 Bq/m3 and bulk averages of 12,500 Bq/m3 (±4,000). Negative correlations are observed between radon emissions, soil temperature and, to a lesser extent, atmospheric pressure. In contrast, increases in radon concentrations were observed during periods of higher rainfall conditions. Therefore, trends in radon concentrations may be decoupled from those of other geochemical parameters (CO2 fluxes and CO2/SO2 plume ratios) during periods of heavy to moderate rainfalls. Multiple Linear Regression statistics (including the effects of soil temperature, atmospheric pressure and tidal forces) led us to compute the residuals given by the difference of measured and calculated 222Rn concentrations. The cross-check between the daily measured radon activities and the absolute variations in radon residuals, for the data collected at the summit station, give us the opportunity to suggest a methodological approach that can be used in the attempt of predicting some major changes in volcanic activity.

► We report one year of radon monitoring at Stromboli volcano during 2008–2009.
► Radon data were filtered for environmental parameters by Multiple Linear Regression.
► Our goal was focussed in predicting some major changes in volcanic activity.
► The proposed methodology may improve geochemical monitoring and volcano surveillance.