Ground geochemical observations for Earthquake and Volcano investigations: the example of the Geochemical Monitoring Network of Tuscany

As a part of a seismic prevention/prediction pilot project, the Regional Government of Tuscany, Italy, has financially supported the setup of a monitoring network (the Geochemistry Network of Tuscany, thereinafter GNT) for studying possible geochemical precursors to seismic activity (Cioni et al., 2007). The GNT is operating since late 2002, and currently consists of six continuous automatic stations installed in the areas of highest seismic risk of Tuscany: Garfagnana, Lunigiana, Mugello, Upper Tiber Valley and Mt. Amiata (Fig. 1). Together with other monitoring networks of Tuscany (i.e. seismic, accelerometric and geodetic networks), the GNT is officially recognized by the Regional Government of Tuscany (Law n. 58 of 16 October 2009) as a "reference tool for the analysis and research on seismic risk". Based on this research, CO2 comes out as the most efficient tracer of the chemical-physical processes occurring at depth, possibly associated to the energy release and/or the permeability variations induced by seismogenic processes. The statistical processing of CO2 continuous signal emerges as a powerful and essential tool to ensure a reliable identification of anomalies, and to possibly increase the confidence in the use of geochemical precursors of earthquakes.