HR: 1340h
AN: H23C-1510    [Abstracts]
TI: Detection and Localization of Hydromechanical Disturbances in a Sandbox using the Self-potential Method
AU: * Crespy, A
EM: crespy@cerege.fr
AF: CNRS-CEREGE, Universite Aix Marseille III, Europole de l'Arbois BP 80, Aix en Provence, 13545, France
AU: Revil, A
EM: arevil@mines.edu
AF: Colorado School of Mines, Green Center, dept of Geophysics 1500 Illinois street, Golden, CO 80401, United States
AU: Linde, N
EM: linde@aug.ig.erdw.ethz.ch
AF: Swiss Federal Institute of Technology, Institute of Geophysics HPP O 2 Schafmattstr. 30, Zurich, 8093, Switzerland
AU: Byrdina, S
EM: lana@ipgp.jussieu.fr
AF: IPGP, 4 Place Jussieu, Paris, 75252, France
AU: Jardani, A
EM: Abderrahim.Jardani@univ-rouen.fr
AF: Département de Géologie et Laboratoire M2C (Rouen), Universite de Rouen Bât.IRESE A Place Emile Blondel, Mont-Saint-Aignan, 76821, France
AU: Boleve, A
EM: boleve@cerege.fr
AF: SOBESOL, Savoie Technolac BP 230, Le Bourget du Lac, 73370, France
AU: Henry, P
EM: henry@cdf.u-3mrs.fr
AF: Collège de France-Chaire geodynamique, Europôle de l'Arbois Bat Le Trocadéro - Aile Sud BP 80, Aix en Provence, 13545, France
AB: The self-potential response during hydromechanical disturbance of water-infiltrated porous material was investigated in the laboratory. Foursandbox experiments were performed to understand the electrokinetic response associated with the injection of a pulse of water and the abstraction of a small volume of pore water. The resulting self-potential signals are measured using 32 Ag/AgCl very sensitive and non-polarising medical electrodes. The injected/abstracted volumes of water are responsible for hydro-mechanical disturbances. In turn, these disturbances generate dipolar electrical anomalies of electrokinetic nature with a distinct electrical signature and an amplitude of few V. The source function is a product of a dipolar Green's function and a source intensity function that depends solely on the product between the streaming potential coupling coefficient of the sand and the pore fluid overpressure with respect to the hydrostatic pressure. Numerical modeling is performed to solve the coupled hydro-mechanical problem and to determine the distribution of the resulting streaming potential in the course of the experiments. We use 2D and 3D algorithms based on the intercorrelation method and wavelet analysis of potential fields to show that the source corresponds to a vertical dipole. These methods are also used to localize the position of the source of the hydromechanical disturbance from the self-potential collected at the top surface of the tank. Applications concern the detection and localization of fracturing in active volcanoes.
DE: 0370 Volcanic effects (8409)
DE: 1835 Hydrogeophysics
SC: Hydrology [H]
MN: 2007 Fall Meeting