Gresse M., Vandemeulebrouck J., Byrdina Svetlana, Chiodini G., Revil A., Johnson T. C., Ricci T., Vilardo G., Mangiacapra A., Lebourg T., Grangeon J., Bascou P., Metral L. (2017). Three-dimensional electrical resistivity tomography of the Solfatara crater (Italy) : implication for the multiphase flow structure of the shallow hydrothermal system. Journal of Geophysical Research : Solid Earth, 122 (11), p. 8749-8768. ISSN 2169-9313.
Titre du document
Three-dimensional electrical resistivity tomography of the Solfatara crater (Italy) : implication for the multiphase flow structure of the shallow hydrothermal system
Année de publication
2017
Auteurs
Gresse M., Vandemeulebrouck J., Byrdina Svetlana, Chiodini G., Revil A., Johnson T. C., Ricci T., Vilardo G., Mangiacapra A., Lebourg T., Grangeon J., Bascou P., Metral L.
Source
Journal of Geophysical Research : Solid Earth, 2017,
122 (11), p. 8749-8768 ISSN 2169-9313
The Solfatara volcano is the main degassing area of the Campi Flegrei caldera, characterized by 60years 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 0.68km(2). 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 60m depth that feeds the Bocca Grande fumarole through a 10m thick 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.
Plan de classement
Hydrologie [062]
;
Géophysique interne [066]
Description Géographique
ITALIE
Localisation
Fonds IRD [F B010071938]
Identifiant IRD
fdi:010071938
