Fig. 2. Conceptual model depicting the release of magmatic fluids from the shallow magmatic source (red) toward the hydrothermal system (yellow) below the Solfatara volcanic crater, where these fluids mix with meteoric liquid (i.e., groundwater from rain; modified from Chiodini et al. [2015], used with permission). PTE (pressurized finite triaxial ellipsoid) and PS (pressurized oblate spheroid) are the deformation sources active at Campi Flegrei at least since 1980 [Amoruso et al., 2014].