An Integrated Modeling Approach for Analyzing the Deformation Style of Active Volcanoes: Somma-Vesuvius Case Study

The deformation style of active volcanoes can provide insight into the structural evolution of their edifices, volcanic activity and associated hazards. The Somma-Vesuvius volcano is considered one of the most dangerous on the planet due to its proximity to the megacity of Naples (Southern Italy). Thus, understanding its deformation style and corresponding long-term structural evolution are critical aspects for risk reduction. Although a large amount of data has already been collected about Somma-Vesuvius, the deformation style affecting its volcanic edifice is still debated. Therefore, we devised an integrated approach to clarify the current state of deformation of this volcano. In particular, we combined analog experiments and finite element (FE) modeling to constrain the current deformation style affecting Somma-Vesuvius and determine the physical parameters controlling its structural evolution. The analog models were built at a scale of 1:100,000 using sand mixtures (brittle analog) and polydimethylsiloxane (ductile analog). The FE models were implemented by considering a three-dimensional time-dependent fluid-dynamic approach performed at both the analog model scale (1:100,000) and actual volcano scale (1:1). We obtained an FE model and a corresponding analog one that faithfully reproduced the observed deformation velocity patterns revealed by differential interferometric synthetic aperture radar (DInSAR) and GPS measurements at Somma-Vesuvius. Overall, our results support the hypothesis that a combined gravitational spreading-sagging process governs the deformation style of Somma-Vesuvius.