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Geochemistry, Geophysics, Geosystems

The active portion of the Campi Flegrei caldera structure imaged by 3-D inversion of gravity data

Authors

  • Paolo Capuano,

    Corresponding author
    1. Dipartimento di Fisica “E. R. Caianiello,”, Università degli Studi di Salerno, Fisciano, Salerno, Italy
    2. Istituto Nazionale di Geofisica e Vulcanologia—Osservatorio Vesuviano, Napoli, Italy
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  • Guido Russo,

    1. Dipartimento di Fisica, Università degli Studi di Napoli Federico II, Napoli, Italy
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  • Lucia Civetta,

    1. Istituto Nazionale di Geofisica e Vulcanologia—Osservatorio Vesuviano, Napoli, Italy
    2. Dipartimento di Scienze della Terra, dell'Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Napoli, Italy
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  • Giovanni Orsi,

    1. Istituto Nazionale di Geofisica e Vulcanologia—Osservatorio Vesuviano, Napoli, Italy
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  • Massimo D'Antonio,

    1. Istituto Nazionale di Geofisica e Vulcanologia—Osservatorio Vesuviano, Napoli, Italy
    2. Dipartimento di Scienze della Terra, dell'Ambiente e delle Risorse, Università degli Studi di Napoli Federico II, Napoli, Italy
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  • Roberto Moretti

    1. Istituto Nazionale di Geofisica e Vulcanologia—Osservatorio Vesuviano, Napoli, Italy
    2. Dipartimento di Ingegneria Civile, Design, Edilizia e Ambiente, Seconda Università degli Studi di Napoli, Aversa, Italy
    3. Department of Geology, St. Mary's University, Halifax, Nova Scotia, Canada
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Abstract

[1] We present an improved density model and a new structural map of the Neapolitan Yellow Tuff caldera, the active portion of the nested Campi Flegrei caldera. The model was built using a new 3-D inversion of the available high-precision gravity data, and a new digital terrain and marine model. The inversion procedure, based on a variable-depth lumped assembling of the subsurface gravity distribution via cell aggregation, gives better defined insights into the internal caldera architecture, that well agree with the available geological, geophysical, and geochemical data. The adopted 3-D gravity method is highly efficient for characterizing the shallow caldera structure (down to 3 km depth) and defining features related to regional or volcano tectonic lineaments and dynamics. In particular, the resulting density distribution highlights a pronounced density low in correspondence of the central portion of the caldera with a detail not available till now. The joint interpretation of the available data suggests a subsurface structural setting that supports a piecemeal collapse of the caldera, and allows the identification of its headwall. Positive gravity anomalies localize dense intrusions (presently covered by late volcanic deposits) along the caldera marginal faults, and the main structural lineaments both bordering the resurgent block and cutting the caldera floor. These results allow us to both refine the current geological-structural framework and propose a new structural map that highlights the caldera boundary and its internal setting. This map is useful to interpret the phenomena occurring during unrest, and to improve both short-term and long-term volcanic hazards assessment.

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