Water-rock interactions during seismic an volcanic activity recorded at Mount Etna by continuous roundwater monitoring

摘要

In this paper we present and discuss geochemical monitoring data for the Acqua Difesa water well on the Southern slopes of Etna volcano, which were gathered by the Geochemical Monitoring System II (GMS II) prototype. This automatic monitoring station provides, every ten minutes, data recording of groundwater temperature, electrical conductivity, pH, redox potential, dissolved CO_2, atmospheric pressure and air temperature. An automatic sampler collects, every 3 days, 2 bottles of water, acidified and not, for subsequent laboratory analyses (including B, NH_4, Fe_(tot) and dissolved CO_2). During the period investigated (March to September 2000) recurrent paroxysmal eruptions occurred at the South-East crater (SEC) of Etna. The Acqua Difesa GMS II station recorded a few geochemical anomalies whose relationships with either volcanic or/and seismic activity are evaluated. We find a possible correlation between the greatest geochemical anomalies, in April 2000, and the most powerful lava fountains episodes at the SEC. Although preliminary, the results open new perspectives to understand better the response of etnean aquifers to volcanic crises. Further continuous monitoring at this and other remote sites on Etna's flank should help us to characterise the dynamics of water-gas-rock interactions associated with volcano-tectonic processes.