3D Audio-Magnetotelluric Imaging of the Aeolian Islands for Geothermal Resource Assessment

The Aeolian Archipelago (southern Italy) hosts several active volcanic islands characterised by widespread hydrothermal manifestations and represents a strategic natural laboratory for assessing geothermal resources in insular volcanic settings. In such environments, Audio-Magnetotelluric (AMT) surveys are particularly effective for imaging shallow geothermal systems, as electrical resistivity is highly sensitive to fluid content, temperature, and hydrothermal alteration. Moreover, AMT data provide key constraints on major structural discontinuities that control fluid circulation at depth.This study presents the results of a large-scale geophysical investigation conducted across the islands of Lipari, Salina, Vulcano, and Panarea, with the aim of providing a geophysically constrained assessment of geothermal resources at the scale of the entire archipelago. The focus is on the application of three-dimensional AMT resistivity imaging, which allows detailed characterization of subsurface electrical properties and offers insights into hydrothermal alteration patterns, fluid pathways, and the structural framework relevant for geothermal exploration.The resulting 3D resistivity models reveal marked lateral and vertical variability in subsurface electrical structure among the investigated islands. These differences reflect contrasting degrees of geothermal system development, variations in fluid circulation regimes, and the role of island-specific structural controls. Rather than indicating a uniform geothermal architecture across the Aeolian Archipelago, the models highlight distinct resistivity patterns and geothermal signatures for each island, emphasizing the heterogeneity of volcanic and hydrothermal processes at the regional scale.Overall, this study demonstrates the effectiveness of AMT resistivity imaging in discriminating between different geothermal settings and in identifying structural controls on fluid circulation in complex volcanic island environments. The results provide a robust geophysical contribution to the construction of an archipelago-scale inventory of geothermal resources and establish a solid basis for future integration with geological, geochemical, and complementary geophysical datasets. This integrated approach is essential for informed evaluation and modelling of sustainable geothermal exploitation scenarios in the Aeolian Islands