A 3D geothermal simulation applied to the Lacco Ameno (Ischia island, Italy) faults system.

Although the faults geometry is generally approximate by 2-D models, when considering fluids circulation in porous media is fundamental to have instead a 3-D view of the area under study, to better evaluate the non-uniform behavior of the circulation and the inhomogeneous distribution of the possible correlated seismogenetic structures. Our research was aimed at studying the Ischia Island faults systems, and particularly the Lacco-Ameno system affected by volcanic gas emissions, mainly CO₂ and H₂O, coming from depth. We have modeled the flux of these magmatic fluids via the 3_D geothermal simulator TOUGH2 code, able to consider non-isothermal flows of multi-component (water and carbon dioxide), multiphase (gas and liquid) fluids, in porous and fractured media. Based on the measured flux of these two components at the surface, and assigning different permeability values between the fault and the host zone, we have estimate, via a 3-D Voronoi tessellation, the magnitude of the released energy by the deep source (H₂O and CO₂ enthalpy injected at depth) and the distribution of the pressure and temperature along the fault-zone, which could be correlated with the not uniform earthquakes location distribution.