First laboratory measurements of seismo-magnetic conversions in fluid-filled Fontainebleau sand

• Published in: Geophysical research letters Vol. 33; no. 1; pp. L01302 - n/a
• Main Authors: Bordes, C., Jouniaux, L., Dietrich, M., Pozzi, J.-P., Garambois, S.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 16.01.2006; Blackwell Publishing Ltd
• Subjects: Earth Sciences; Earth, ocean, space; Environmental Sciences; Exact sciences and technology; Exploration Geophysics; Geophysics; Global Changes; Hydrogeophysics; Hydrology; Magnetic and electrical methods; Physics; Sciences of the Universe; Seismic methods; experimental studies; magnetic field; magnetometers; decoupling; pore fluid; Laboratory measurement; vibration; coupling; sand; induction; Wave propagation; noise; accelerometers; Electric dipole; Propagation mode; porous media; seismic waves; seismoelectromagnetic; rock physics; seismoelectric; electric; seismomagnetic; magnetic; electrokinetic
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2005GL024582

Seismic wave propagation in fluid‐filled porous materials induces electromagnetic effects due to small relative pore‐fluid motions. In order to detect the seismo‐magnetic couplings theoretically predicted by Pride (1994), we have designed a small‐scale experiment in a low‐noise underground laboratory which presents exceptional electromagnetic shielding conditions. Our experiment included accelerometers, electric dipoles and induction magnetometers to characterize the seismo‐electromagnetic propagation phenomena. To assess the electrokinetic origin of the measured electric and magnetic fields, we compared records obtained in dry and fluid‐filled sand. Extra care has been taken to ensure the mechanical decoupling between the sand column and the magnetometers to avoid spurious vibrations of the magnetometers and misinterpretations of the recorded signals. Our results show that seismo‐electric and seismo‐magnetic signals are associated with different wave propagation modes, thus emphasizing the electrokinetic origin of these effects.