Multidisciplinary studies of diffuse soil CO2 flux, gas permeability, self-potential, soil temperature highlight the structural architecture of Fondi di Baia craters (Campi Flegrei caldera, Italy)

We present in this paper the results of a geophysical and geochemical survey of self potential, diffuse soil CO2 flux, soil temperature and gas permeability carried out in the Fondi di Baia craters on the western sector of Campi Flegrei caldera, one of the most hazardous active volcano in Italy. Work was aimed at highlighting the small-scale volcano-tectonic structures of this Holocene edifice and at evaluating its state of fracturing, in order to ascertain possible volcanic hazard for future vent reopening. The central sector of Campi Flegrei (Solfatara volcano-Pisciarelli) is indeed the one most affected by ground deformation and intense hightemperature fumarolic activity, nevertheless it cannot be ruled out a future vent opening along the western collapsed margin of the caldera, where Fondi di Baia craters are located. Our results show that the Fondi di Baia craters are characterized by a medium-high release of hydrothermal fluids through fractures that mimic the main volcano-tectonic structures of this portion of the caldera. Moreover, results indicate that, in case of a future volcanic reactivation, these previous structures could as well be possible paths for magma ascent. We provide a first estimate of the total flux of CO2 from Fondi di Baia diffuse degassing structure, quantified in 10.06 ± 1.07 t*d-1.