GNGTS 2015 - Atti del 34° Convegno Nazionale

170 GNGTS 2015 S essione 1.3 Mercalli G.; 1883: Vulcani e fenomeni vulcanici in Italia. Milano, (rist. anast., Bologna 1981), 374 pp. Perrey A.; 1846: Memoire des tremblements de terre ressentis pendant les années 1845 et 1846. Mémoires de l’Acadèmie des sciences, arts et belles-lettres de Dijon, années 1845-1846, partie des sciences, 393-479. Perrey A.; 1848: Mémoire sur les tremblements de terre de la péninsule italique. Académie Royale de Belgique, Mémoires couronnées et mémoires des savants étrangers, 22, Bruxelles, 144 pp. Pondrelli S., Morelli A., Ekstrom G., Mazza S., Boschi E., Dziewonski A.M.; 2002: European–Mediterranean regionalcentroid-moment tensors: 1997–2000. Phys. Earth Planet. Inter., 130, 71–101. Reuther C. D., Eisbacher G. H.; 1985: Pantelleria rift-crustal extension in a convergent intraplate setting. Geol. Rund., 74, 585–597. Riccò A.; 1891: Tremblements de terre, soulèlevement et eruption sous-marine à Pantelleria. Comptes rendues, 23 novembre; fasc. 21, p. 753. Rigano R., Arena L., Barbano M.S., Antichi B., Azzaro R.; 1998: Sismicità e zonazione sismogenetica in Sicilia occidentale. 17 National meeting Gruppo Nazionale Geofisica della Terra Solida, abstracts, 161-162. Rovida A., Camassi R., Gasperini P., Stucchi M. (ed); 2011: CPTI11, the 2011 version of the Parametric Catalogue of Italian Earthquakes, Milano, Bologna, http://emidius.mi.ingv.it/CPTI. Washington H. S.; 1909: Submarine Eruptions 1831 and 1891 near Pantelleria, Am. J. Sci., IV, 27,131-150. Wiemer S.; 2001: A software package to analyze seismicity: ZMAP. Seism. Res. Letters, 72 (3), 373-382. Magma degassing, heating and deformation at Campi Flegrei caldera G. Chiodini 1 , F. Quareni 1 , S. Caliro 2 , C. Cardellini 3 , A.R. Mangiacapra 2 , Z. Petrillo 2 1 1 INGV, Sezione di Bologna, Italy 2 INGV, Sezione di Napoli, Italy 3 Dipartimento di Fisica e Geologia, Università di Perugia, Italy Introduction. One of the most problematic issues of modern volcanology is the trigger mechanism of unrests at calderas (Newhall and Dzurisin, 1988; Lowenstern et al. , 2006; Acocella et al., 2015). Here we focus on Campi Flegrei caldera (CFc) which has recently given clear signs of potential re-awaking (Chiodini et al. , 2012). In its history, CFc alternated phases of uplift followed by subsidence periods over a range of different timescales (Rosi et al. , 1983; Di Vito et al. , 1999; Orsi et al. , 2004; Morhange et al. , 2006). There are evidences of decades-long inflation prior to the last magmatic eruption, the AD 1538 Monte Nuovo eruption as described in Dvorak and Mastrolorenzo (1991). The Monte Nuovo eruption was followed by a general subsidence which lasted to the early 50s when inflation resumed and culminated into two major uplift, accompanied by an intense seismic activity (“bradyseism”), in 1969-1972 and in 1982-1984, with a total vertical displacement of 3.8±0.2m (Del Gaudio et al. , 2010, and references therein). Since 1985, a slow subsiding phase, interrupted only by few minor uplifts, affected CFc until 2005 when a new inflation phase started, with an accelerating trend in the next following years. A maximum vertical displacement of about 31 cm has been attained in August 2015, according to the measurements referred in http://www.ov.ingv.it/ov/it/bollettini. This current inflation is accompanied by a weak seismicity, by a strong increase in the fumarolic activity, and by remarkable compositional variations of the fumaroles of Solfatara, the most active zone of CFc (Chiodini et al. , 2012, 2015 and references therein). At Solfatara, thirty years of compositional data of the main fumarolic vent are made available for investigate the causes of the processes controlling the unrest. This long and detailed time series of geochemical data related to hydrothermal fluids released by a caldera is practically unique at global scale. Surprising correlations among the fluid compositions and the geophysical signals, as well as the results of physical numerical modelling, indicate that the ongoing unrest is controlled by repeated injections of magmatic fluids into the hydrothermal system of CFc. The process is