The Solfatara Magmatic-Hydrothermal System Geochemistry, Geothermometry and Geobarometry of Fumarolic Fluids

Solfatara volcano is situated close to the center of the Campi Flegrei caldera which, in the past, has alternatively experienced phases of resurgence and subsidence, traditionally indicated with the term bradyseism. Ludovico Sicardi (1895-1987) was an Italian scientist, who carried out pioneering studies on the Solfatara and other Italian volcanoes (Vesuvius, Stromboli, Vulcano, Panarea, Salina, and Etna), developing innovative instruments and methods to sample and analyze volcanic gases (Calabrese et al. 2020). He wrote several papers on the Solfatara of Pozzuoli, one of which, in Italian, was published on the Bulletin Volcanologique in 1956. In that paper, he noted that among the numerous craters of the Campi Flegrei, on the Gulf of Naples, that of the Solfatara of Pozzuoli is the only one that has probably preserved an uninterrupted fumarolic activity for at least two millennia. In 1538, a few kilometers away, a new volcanic vent opened and created its edifice in 48 hours. It is known as Monte Nuovo and reaches an elevation of 140 m, but the only remnant of that eruptive episode of such a short duration are some weak fumarolic emissions. The fumaroles of the Solfatara of Pozzuoli, on the other hand, reveal a truly unusual persistence, even if the thermal level of the exhalation is not excessive, since the alternation of different phases of activity is quite common in volcanic centers (Sicardi 1956).