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http://hdl.handle.net/2122/10998
Authors: | Gresse, Marceau* Vandemeulebrouck, Jean* Byrdina, Svetlana* Chiodini, Giovanni* Revil, André* Johnson, Timothy C.* Ricci, Tullio* Vilardo, Giuseppe* Mangiacapra, Annarita* Lebourg, Thomas* Grangeon, Jacques* Bascou, Pascale* Metral, Laurent* |
Title: | Three-Dimensional Electrical Resistivity Tomography of the Solfatara Crater (Italy): Implication for the Multiphase Flow Structure of the Shallow Hydrothermal System | Journal: | Journal of Geophysical Research: Solid Earth | Series/Report no.: | /122 (2017) | Issue Date: | 27-Nov-2017 | DOI: | 10.1002/2017JB014389 | Keywords: | 3-D gas-dominated reservoir feeds the Bocca Grande fumarole at 164 degrees Celsius through a ~10 m thick The Fangaia mud pool and Pisciarelli fumarole are both conductive liquid-dominated plume |
Subject Classification: | 04.08. Volcanology | Abstract: | The Solfatara volcano is the main degassing area of the Campi Flegrei caldera, characterized by 60 years of unrest. Assessing such renewal activity is a challenging task because hydrothermal interactions with magmatic gases remain poorly understood. In this study, we decipher the complex structure of the shallow Solfatara hydrothermal system by performing the first 3-D, high-resolution, electrical resistivity tomography of the volcano. The 3-D resistivity model was obtained from the inversion of 43,432 resistance measurements performed on an area of ~0.68 km2. The proposed interpretation of the multiphase hydrothermal structures is based on the resistivity model, a high-resolution infrared surface temperature image, and 1,136 soil CO2 flux measurements. In addition, we realized 27 soil cation exchange capacity and pH measurements demonstrating a negligible contribution of surface conductivity to the shallow bulk electrical conductivity. Hence, we show that the resistivity changes are mainly controlled by fluid content and temperature. The high-resolution tomograms identify for the first time the structure of the gas-dominated reservoir at 60mdepth that feeds the Bocca Grande fumarole through a ~10mthick channel. In addition, the resistivity model reveals a channel-like conductive structure where the liquid produced by steam condensation around the main fumaroles flows down to the Fangaia area within a buried fault. The model delineates the emplacement of the main geological structures: Mount Olibano, Solfatara cryptodome, and tephra deposits. It also reveals the anatomy of the hydrothermal system, especially two liquid-dominated plumes, the Fangaia mud pool and the Pisciarelli fumarole, respectively. |
Appears in Collections: | Article published / in press |
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2017_Gresse_3D Electrical Resistivity Tomography of Solfatara.pdf | 19.36 MB | Adobe PDF | View/Open |
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