GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 1.3 165 MULTIPHYSICS FINITE ELEMENT MODELLING OF SOLFATARA HYDROTHERMAL SYSTEM R. Castaldo 1 , A. Barone 1 , G. Chiodini 2 , G. Gola 3 , G. Solaro 1 , P. Tizzani 1 1 National Research Council (CNR), Institute for the Electromagnetic Sensing of the Environment (IREA), Naples, Italy 2 National Institute of Geophysics and Volcanology (INGV), Bologna, Italy 3 National Research Council (CNR), Institute for Geosciences and Earth Resources (IGG), Pisa, Italy In volcanic environments, fluids play a key role in controlling and governing the evolution of magmatic processes and eruptions. The high permeable volcanic rocks are readily infiltrated by meteoric water that may encounter fluids rising up from deep magma feeding systems, thus developing shallow hydrothermal systems. The reliable imaging of fluid storages and the accurate tracking of their movements within the crust are therefore critical in evaluating the nature and likelihood of future natural/man-induced earthquake or volcanic activity and their relative hazard monitoring and assessment. In Campi Flegrei caldera, the Solfatara crater was formed at ~4.2 ka during the third epoch of caldera activity. It is a 0.5 ×0.6 km sub-rectangular depression, whose geometry is controlled by N40-50W and N50E trending fault systems. Nowadays, this crater is characterized by intense diffuse degassing and fumarolic emissions; specifically, a series of small uplift episodes and seismic swarms mainly occurred at Solfatara from 1984 to 2006, during the subsidence of whole caldera. These earthquakes are likely to be associated with a buried cavity filled with a water-vapour mixture at poor gas-volume fractions. In this scenario, we built up a 2D model by using the geological and geophysical data and fluid reservoir parameters (Fig. 1). This information is used within a multiphysics Finite Element Model that allows for a description of time-dependent mixed conductive/convective thermal model. The model time evolution starts 4.2 ka: we first perform the preliminary stationary conductive thermal model Fig. 1 - (a) DEM of Campi Flegrei caldera with the location of AA’ model trace. (b) Geometry and triangular mesh of the FE model. The segments represent the domains limits and the considered fractures. (c) Conductive/convective thermal model results after 4.2 ka. The natural seismicity occurred between 2005 and 2020 is superimposed.