Electric potential anomaly induced by humid air convection within Piton de La Fournaise volcano, La Réunion Island

Abstract : Self potential (SP) anomalies over Piton de La Fournaise volcano (La Réunion Island) are generally interpreted as resulting from meteoritic water porous flow. However, there is no clear evidence that the subsurface is permanently saturated. Recently, a convective subsurface airflow has been evidenced within a quiescent cone at Piton de La Fournaise (Formica Leo). SP and thermal anomalies are reported on the unsaturated edifice and are seen to be correlated. It is proposed that the SP signal is generated by the movement of water films present on the porous matrix, induced by the intense humid airflow within Formica Leo. The structure of the cone, determined from electrical resistivity tomography (ERT), ground penetrating radar (GPR), microgravimetric and kinematic GPS data, is used to constrain a 3D numerical model of the air convection. The calculated temperature is then used to derive the related SP signal, the electrokinetic coupling coefficient being estimated from direct observations of the electrical resistivity of the soil. Extrapolating these results to the scale of the volcano, it is thus proposed that a cold humid airflow enters the flanks of the 400 m-high terminal dome, flows up along the sloped and stratified volcanic layers before exiting through the vertical fractures around the Dolomieu collapse. It is demonstrated that the SP anomalies catches the main features recovered over the entire volcano. This result strongly suggests that humid airflow may play a major role on the generation of SP anomalies at Piton de la Fournaise volcano, and perhaps in other unsaturated volcanic edifices.
Type de document :
Article dans une revue
Geothermics, Elsevier, 2017, 65, pp.81-98. 〈10.1016/j.geothermics.2016.01.003〉
Liste complète des métadonnées

Littérature citée [67 références]  Voir  Masquer  Télécharger

http://hal.univ-reunion.fr/hal-01376484
Contributeur : Fabrice Fontaine <>
Soumis le : mercredi 2 novembre 2016 - 10:55:19
Dernière modification le : mercredi 19 septembre 2018 - 01:35:49
Document(s) archivé(s) le : vendredi 3 février 2017 - 12:43:10

Fichier

2017-(38)-Piton-de-La-Fournais...
Fichiers produits par l'(les) auteur(s)

Identifiants

Citation

Raphaël Antoine, Anthony Finizola, Téodolina Lopez, David Baratoux, Michel Rabinowicz, et al.. Electric potential anomaly induced by humid air convection within Piton de La Fournaise volcano, La Réunion Island. Geothermics, Elsevier, 2017, 65, pp.81-98. 〈10.1016/j.geothermics.2016.01.003〉. 〈hal-01376484〉

Partager

Métriques

Consultations de la notice

554

Téléchargements de fichiers

3