3D ultra-high resolution seismic imaging of shallow Solfatara crater in Campi Flegrei (Italy): New insights on deep hydrothermal fluid circulation processes.

ABSTRACT: Seismic tomography can be used to image the spatial variation of rock properties within complex geological media such as volcanoes. Solfatara is a volcano located within the Campi Flegrei, a still active caldera, so it is of major importance to characterize its level of activity and potential danger. In this light, a 3D tomographic high-resolution P-wave velocity image of the shallow central part of Solfatara crater is obtained using first arrival times and a multiscale approach. The retrieved images, integrated with the resistivity section and temperature and the CO₂ flux measurements, define the following characteristics: 1. A depth-dependent P-wave velocity layer down to 14?m, with V_p?2 degassing; 2. An intermediate layer, deepening towards the mineralized liquid-saturated area (Fangaia), interpreted as permeable deposits saturated with condensed water; 3. A deep, confined high velocity anomaly associated with a CO ₂ reservoir. These features are expression of an area located between the Fangaia, water saturated and replenished from deep aquifers, and the main fumaroles, superficial relief of the deep rising CO₂ flux. Therefore, the changes in the outgassing rate greatly affect the shallow hydrothermal system, which can be used as a "mirror" of fluid migration processes occurring at depth.

SUBMITTER: De Landro G 

PROVIDER: S-EPMC5469761 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature