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Imaging of volcano-tectonic features and plumbing system of the Campi Flegrei caldera by magnetotelluric survey

Maria Giulia Di Giuseppe 1, Roberto Isaia 1,  Antonio Troiano 1, Claudio De Paola 1, Fabio Pagliara1

Abstract

Electromagnetic imaging can proficiently detect the volcano-tectonic features defining the structure of a Volcano. A magnetotelluric (MT) survey recently performed allowed to obtain a 3D tomography of the shallow and deep structure of the whole Campi Flegrei caldera (CFc). The resistivity image shows different anomalies at different scales resulting from the complex volcano-tectonic setting of the caldera, its plumbing system, the geothermal reservoirs, and the configuration of the plumbing and geothermal systems. The produced 3D resistivity imaging, dentified the electrical pattern of the investigated structure down to a depth of 20 km below sea level. Results have been interpreted considering the volcanological and petrological features available in the wide literature on the CFc. The electromagnetic reconstruction of the volcano's deep internal structure points out the configuration of the plumbing system and the main structures for the ascent of magma and magmatic fluids, at least below a large continental portion of the caldera. The preliminary obtained picture of the electrical resistivity distribution with depth suggests that the CF caldera plumbing system appears to be formed by distinct branches with a shallower geothermal system well developed below the Solfatara-Agnano area fed by a deeper source. The main fault system, acting as a preferential pathway for magmatic fluids, is also identified. Lateral variation of the anomaly also provide indication of the volcano tectonic features associated to the caldera collapse occurred at different scale. The resistivity model allows delineating major clues of the caldera's setting.