Seismic-ionospheric effects in F2-layer of an ionosphere in time of heliogeophysical disturbances

We studied properties of traveling ionospheric disturbances of the electron density (horizontal dimensions are 1-3 thousand km, excess over the background is 15-30 %) that were formed in the F2-layer 10-15 hours prior to disastrous earthquakes in quiet and disturbed conditions. Inhomogeneities move horizontally with transonic speed at over 10000 km in the trajectories oriented approximately along the great-circle arc passing through the corresponding epicenter. The self-descriptiveness of the investigation depended on spatial-temporal differences of the ionosphere dynamics typical of disturbed conditions and the dynamics of seismogene quasideterministic macroscale ionospheric inhomogeneities, which are stable in form and velocity of travel and have random instants of onset.