THE SELF-POTENTIAL METHOD: DID THE UGLY DUCKLING OFENVIRONMENTAL GEOPHYSICS TURN INTO A BEAUTIFUL SWAN?

摘要

The self-potential method consists in measuring passively the electrical potential responseassociated with in situ polarization mechanisms occurring in the Earth. The two main mechanisms ofpolarization are the redox contribution (with applications concerning contaminant plumes and orebodies) and the streaming potential associated with ground water flow. Discovered in the first part of theXIX Century, the self-potential method has been considered for a long period of time as a scientificcuriosity except in the prospection of ore bodies. Thanks to the work by researchers like Nourbehecht,Fitterman, Corwin, Sill, Ishido, Morgan, Aubert, Fournier, and others, a better understanding of theunderlying physics of the self-potential was reached during the eighties. Over the past 15 years, the self-potential method has been developed to the point where it can be considered as a powerful method innear surface geophysics to invert non-intrusively the pattern of ground water flow and the distribution ofthe redox potential in shallow contaminated aquifers. A short history of the self-potential method isgiven and recent quantitative developments and future trends will be discussed especially regarding theapplications of the self-potential method in hydrogeophysics. We will also discuss recent achievementson self-potential stochastic tomography and the joint inversion of self-potential signals with othergeophysical datasets. The ugly duckling of environmental geophysics has definitively turned into abeautiful swan that offers a unique sensitivity to underground phenomena.