Soil radon concentration and effective stress variation at Mt. Etna (Sicily) in the period January 2003-April 2005

In this study we discuss the relationship between the in-soil radon concentration and the effective stress variation at Mt. Etna volcano in the period January 2003-April 2005. The acquired radon concentration trend was compared with the one obtained by the b-value variation analysis in the frequency-magnitude relationship for earthquakes that occurred at Mt. Etna volcano (Sicily) during the investigation period. The b-value calculated using both the maximum likelihood and the least square methods shows a similar trend and, in particular, an increase starting a few months before the 7th September 2004 eruption and a decrease during the following 9 months. A similar trend was recorded during 2003 when a recharging magma phase of the volcano occurred. Results obtained by studying the b-value trend and the comparison with in-soil radon concentration are also discussed. (C) 2008 Elsevier Ltd. All rights reserved.