Hydrothermal system dynamics at Pisciarelli fumarole field (Campi Flegrei): insights from geophysical and numerical modelling

The Pisciarelli fumarolic-hydrothermal area (Campi Flegrei caldera, Southern Italy), together with the adjacent Solfatara maar-diatreme, is a critical site due to the recent increase in volcanic activity. This includes very high CO2 fluxes (exceeding 600 tons/day), continuous morphological changes and frequent seismic events. This study aims to reconstruct the architecture and fluid dynamics of the Pisciarelli fumarole field by integrating geophysical imaging and thermo-fluid dynamic numerical modelling. A detailed 3D petrophysical model was developed from electrical resistivity, time-domain induced polarization and self-potential data, and was further constrained by existing volcanological and geochemical information. Thermodynamic simulations of a hot H2O-CO2 mixture circulating in the shallow hydrothermal system of Pisciarelli were carried out using the TOUGH2 numerical code with the EOS2 module. This modelling approach enabled detailed characterization of the system’s current dynamics, including temperature distribution, gas pressure, gas saturation levels, and fluid flow pathways. The results emphasize the pivotal role of the main fault system in controlling fluid accumulation and migration, which in turn drives the intense degassing activity observed at Pisciarelli. These findings provide new insights into the physical state of the Pisciarelli-Solfatara hydrothermal complex and contribute to assessing the potential for sudden explosive hydrothermal events under current conditions.