This study is concerned with the electric potential induced by deformation, fracturing and sliding of non-piezoelectric geomaterials. In experiments, the acoustic emissions together with electric potential measurements were also measured in order to see how the so-called seismic electric signals are associated with new fracture occurrence and propagation and sliding in case of existing discontinuities. The outcomes of this experimental study may explain why such electric potential variations may occur during the fracturing and sliding of non-piezoelectric geomaterials. On the basis of these outcomes, their possible implications in geo-engineering and geo-science are discussed.
Ce travail concerne 1e potentiel electrique produit par la deformation, 1a fracture ou le glissement du materiel geologique non-piezoelectrique. Aux experimentations, on a mesure 1es emissions acoustiques avec le potentiel electrique afın de constater la relation entre les phenomènes de glissement ou de formation et de propagation de nouvelles fractures le long des discontinuites existantes. Les resultats de ce travail experimental expliquent pourquoi de telles variations de potentiel electrique se produisent durant le glissement ou la fracture du materiel non- piezoelectrique. Sur la base de ces resultats, on a discute de leurs eventuelles implications dans les domaines de 1a geologie et de 1a geo-ingenierie.
Diese Studie befasst sich mit dem elektrischen Potential das durch die Deformation, Bruchbildung und Gleiten von nicht-piezoelektrischen Geomaterialien induziert wird. In Experimenten wurden die akustischen Emissionen zusammen mit elektrischen Potentialmessungen gemessen, um zu sehen, wie die so genannten seismischen elektrischen Signale mit neuer Bruchbildung und Ausbreitung sowie Gleiten im Falle von vorhandenen Diskontinuitaten verbunden sind. Die Ergebnisse dieser experimentellen Untersuchungen könnten erklaren warum elektrische Potential Schwankungen wahrend der Bruchbildung und dem Gleiten von nicht-piezoelektrischen Geomaterialien entstehen. Auf der Basis dieser Ergebnisse, wurden ihre möglichen Implikationen in Geoingenieurwissenschaften behandelt.
Introduction The electrical resistivity variation of ground before and during earthquakes occurs, and it was used for the prediction of earthquakes in Kamchatka by Sobolev (1975). He and his co-workers used some set-ups aligned in the directions of NS and EW to measure electric potential and electrical resistivity of ground. Varotsos and his co-workers also applied this technique to actual earthquake predictions (Varotsos & Alexopolous, 1984). Although this method is widely known as the VAN-method, Sobolev and his-co-workers or earlier researchers probably deserve the credit for this method. Since a sound physical model for this method could not be put forward by Sobolev and his followers so far, it is still controversial and some opponents of this method reject its validity. The electric potential of geomaterials is always considered to be due to piezoelectric substances contained in rocks. The authors undertook an experimental study for understanding the mechanism of electric potential variations and electrical resistivity changes during deformation and seepage processes of various geomaterials, which ranged from crystals, gouge-like materials to rocks in their previous reports (Aydan et al. 2001, 2002 and Aydan & Daido 2002). This study is a further contribution to the understanding of the electric potential induced by deformation, fracturing and sliding of non-piezoelectric geomaterials.