Experiments and Modelling of Seismoelectrics in the Ultrasonic Range: A Comparison With Electrokinetic Theory

Abstract : Acoustical wave propagation in a fluid-filled porous media creates electromagnetic (EM) disturbances through a physical process referred in the literature as seismoelectric (SE) conversion. Two EM fields result from this conversion, one accompanies the seismic wave in the form of a transient electric field and the other is generated at interfaces and propagates independently with an electromagnetic wave behaviour. The latter has an arguably high potential of application in near-surface exploration, possibly comparable to other indirect EM methods. In what follows, an experimental setup conceived to measure both SE fields mentioned above was employed in the study of a porous saturated homogeneous medium with (1) and without (2) a thin layer inside. It was seen that measuring absolute potentials is more efficient for detecting the EM-wave generated at interfaces than using electric fields estimated from measured potential differences. Using a numerical code and an experimental source, the measured data was compared with the modelling showing there is a fair agreement between experiments and electrokinetic theory. Our results are promissing and open the path for a more in depth investigation of the SE conversion phenomena and its relation with physical properties.