The underlying model for defect parameters in materials of geophysical interest and Seismic Electric Signals

Abstract. Here, we investigate whether the bulk or the shear is the appropriate modulus for the defect parameters in different materials by focusing on those of geophysical interest. We show that the self-diffusion process and just also the bulk modulus should be related to defect parameters. It is this interrelation which accounts for the emission of electric signals before fracture, and is thus in accordance with the physical basis of the Seismic Electric Signal prior to earthquakes in Greece.