  The present paper deals with reliability of a gradient of atmospheric
electric field potential as an indicator of seismic activity increase. With
this in view, records of atmospheric electric field potential gradients of
Caucasus region for 1953-1992 with respect to periods before average and large
earthquakes, which took place in the same time interval, were considered. It is
worth to pay attention to the fact that the avalanche-like unstable model of
fault formation based on theoretical model of self-generated
seismo-electromagnetic oscillations of LAI system explains convincingly
spectral succession of electromagnetic emission frequency of the periods
preceding earthquakes.
