Extracting quantitative dynamics from 222Rn gaseous emissions of mud volcanoes

In this work we explore the inner time dynamics of Rn-222 gaseous emissions of a bubbling mud volcano located in northern Apennines (Italy). In order to discriminate shallow environmental effects, barometric and temperature series have been also monitored and compared with Rn-222 data. The Lomb periodogram and the Higuchi techniques have been applied to characterize the time dynamics of the experimental time series. No significant periodicity has been identified and the power spectrum is characterised by a monotonic decrease with frequency f which follows a typical power law (proportional tof(-alpha)). Our findings suggest to consider the Rn-222 time series as a realization of an antipersistent stochastic process. This indicates that the dynamics underlying Radon emissions from bubbling mud volcanoes is complex and that a relatively large number of unknown factors control the process. This result discourages the use of bubbling gaseous emissions for the monitoring of geodynamic processes. Copyright (C) 2003 John Wiley Sons, Ltd.