: The electrical resistivity variation of ground before and during earthquakes occurs, and it was used for the prediction of earthquakes in Kamtchatka 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 and applied actual earthquake predictions (Varotsos et al. 1984) and it is called the VAN-method. Since they could not put forward a sound physical model for their method, it is still controversial and some opponents of this method (i.e. Geller 1986 etc.) reject its validity. The authors undertook an experimental study to make further contributions to the understanding of electric potential variations and electrical resistivity studies during deformation and fracturing processes of geomaterials, which ranges from crystals, gouge-like materials to rocks. Furthermore, the measurements of acoustic emissions together with electric potential measurements were also carried out in order to see the so-called seismic electric signals related to fracture occurrence and propagation. This article describes the outcomes of this experimental study to explain why such electric potential variations may occur during the deformation and fracturing of geomaterials. On the basis of these outcomes, the authors discuss their possible implications in geo-mechanics, geo-science and geo-engineering.
1 INTRODUCTION
Sobolev (1975) was first to point out the existence of electrical resistivity variation of ground before and during earthquakes and he used it for the prediction of earthquakes in Kamtchatka. 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 and applied actual earthquake predictions (Varotsos et al. 1984) further elaborated this method. This method is called VAN-method. This method assumes that seismic electric signals (SES) precede before main shocks. The amplitude of these signals and locations of observation stations are used to predict the location, magnitude and time of earthquakes. Since they could not put forward a sound physical model for these signals during the fracturing process of rocks, it is still controversial and some opponents of this method (i.e. Geller 1986 etc.) reject the validity of their method.
