GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.3 GNGTS 2023 Thermo-poroelastic modelling of Solfatara crater through Finite Element method A. Barone 1 , G. Gola 2 , A. Pepe 1 , P. Tizzani 1 , R. Castaldo 1 1 National Research Council (CNR), Institute for the Electromagnetic Sensing of the Environment (IREA), Naples, Italy 2 National Research Council (CNR), Institute for Geosciences and Earth Resources (IGG), Torino, Italy In volcanic framework, the presence of fluids and their possible migration in the crust can affect the evolution of magmatic processes and eruptions occurrence. Meteoric water can for instance infiltrate the high permeable volcanic rocks and develop shallow hydrothermal systems; therefore, descending meteoric water may encounter fluids rising up from deep magma feeding systems. The reliable imaging of fluid storages and accurate tracking of their movements within the crust turn out to be crucial for the evaluation of the seismic and volcanic activity. In this scenario, Campi Flegrei caldera is an interesting example of fluids interaction of different nature, especially at Solfatara crater, where the occurrence of diffuse degassing, high temperatures and bradyseism phenomenon highlight its complexity as a volcanic system. The Solfatara crater was formed at about 4.2 ka (Smith et al. 2011) during the third epoch of the activity of Campi Flegrei caldera. It consists of a 0.5 × 0.6 km sub-rectangular depression, whose geometry is controlled by N40-50W and N50E trending fault systems (Costa et al., 2022). Nowadays, intense diffuse degassing and fumarolic emissions characterize the Solfatara crater, and a series of small uplift episodes and seismic swarms have occurred in this area, particularly from 1984 to 2006 when the whole caldera subsided. Specifically, these earthquakes are likely to be associated with a buried cavity filled with a water-vapour mixture at poor gas-volume fractions. In this framework, we propose a multi-physics study of Solfatara volcanic system by integrating 2D thermodynamic and poro-elastic model results. The first model is performed by considering the available geological and geophysical information, such as the main structural elements, crustal parameters (e.g., density, porosity, thermal conductivity, heat capacity, permeability) and the initial temperature distribution in terms of conductive regime (Castaldo et al., 2019). This information is merged into a multi-physics Finite Element Model through the use of COMSOL Multiphysics software that allows the simulation of the crustal thermal regime beneath the Solfatara crater by performing a time-dependent convective thermal model in porous media. At the same time, we simulate the fluids circulation in accordance with the Darcy’s Law by considering the bi-phasic water properties (i.e., liquid and