Radioactivity outbursts from geophysical events

Radon and radon daughters anomalies, referred to as geophysical events, are usually studied in order to understand the mechanisms involved in the subsoil geochemistry. In fact, the concentration fluctuations of those elements are used to evaluate the evolution of volcanic systems or seismic zones. Results concerning long- and short-lived radon and thoron decay products, concentrations in fumaroles, or accompanying an eruptive plume, have been useful in determining volumes of magma undergoing degassing; anomalies of radon in soil and ground water have also proved useful in seismic studies. Those anomalous behaviours are generally observed as increases in the radioactivity levels of the studied systems, producing radioactivity outbursts from the Earth to the human environment. In this paper, an analysis of the contribution to the local radioactivity level produced from anomalous outbursts due to eruptive events is made. (author). 20 refs, 1 tab