  It is postulated that the preseismic electric signals (SES) are generated by
the piezoelectric mechanism applied on small rock grains - blocks during their
stress load until fracturing. Specifically, the square electric train pulses
are generated by the combination of a stress increase phase which generates a
positive piezostimulated polarized current pulse (PSPC) followed, in a short
time, by the stress decrease phase at fracturing level which generates a
negative piezostimulated depolarized current pulse (PSDC). Moreover, it is
shown that the SES signals are closely related to the tidally triggered
lithospheric stress maxima - minima. Examples of SES signals are presented in
relation to the tidally triggered lithospheric oscillation (k2, S2, M1) of T =
12hours / 14 days, while some comments are made as far as it concerns their use
in short-term earthquake prediction.
