Integrated geophysical, geochemical and modelling constraints on the geothermal system of Pantelleria Island (Italy): results from the PANTA REI project

Pantelleria Island represents one of the most promising yet poorly constrained geothermal targets in the Mediterranean volcanic domain, characterized by high geothermal gradients, widespread hydrothermal manifestations, and a complex volcano-tectonic setting. The Pantelleria islAnd geotheRmal ExploratIon (PANTA REI) project, in the framework of the INGV–MUR project Pianeta Dinamico, aimed to provide a comprehensive reassessment of the geothermal system of Pantelleria through an integrated, multidisciplinary approach combining geophysical imaging, structural and seismic analyses, geochemical investigations, and numerical modelling.

The integrated interpretation of magnetotelluric, gravity and magnetic data provided a coherent geophysical model of the shallow crust of Pantelleria, resolving key contrasts in electrical resistivity and density, as well as thermal constraints, and highlighting the main volcano-tectonic structures of the island. Geophysical modelling enabled the identification of two shallow geothermal reservoirs in the central–southern sector of the island, structurally controlled by caldera-related faults and resurgent blocks.

To further constrain this geophysical model, seismic, geodetic and structural investigations were strengthened through the deployment of temporary seismic stations and GNSS receivers. Seismic noise analysis allowed the definition of the first 1D shear-wave velocity model of Pantelleria Island, enabling an improved relocation of the recorded seismicity. The resulting earthquake distribution is characterized by low background activity and shows spatial consistency with the main volcano-tectonic structures, while GNSS measurements confirm a long-term subsidence trend affecting the central sector of the island.

High-resolution geochemical datasets, together with surface temperature measurements, were integrated within a GIS environment to support the spatial interpretation of hydrothermal manifestations and fluid circulation patterns. The distribution of fumarolic and hydrothermal emission areas coupled  with the defined structural pattern show as fluids circulating mainly along faults and fracture systems of the caldera.

The resulting multidisciplinary dataset was integrated into an updated conceptual model of the Pantelleria geothermal system, which provided the basis for steady-state numerical simulations of fluid circulation and heat transport. Numerical modelling, performed using TOUGH2 and constrained by a petrophysical model derived from geophysical results, provides robust quantitative constraints on the geothermal potential of the island and supports the evaluation of small- to medium-scale exploitation scenarios consistent with the natural state of the system.