Our simulations revealed that TEC disturbances above
the epicenter, caused by various seismogenic sources are
in satisfactory qualitative agreement with experimental data
of GPS TEC measurements. It was shown that small-scale
IGWs were able to produce disturbances of the zonal electric field over the epicentral area. However the amplitude of these disturbances does not reproduce the observedlocal TEC deviations. Simulation results for small-scale
IGWs demonstrate that the local positive effect in TEC
over the epicentral area is related to the growth of the ratio
n(O)/n(N2). When the penetration of the vertical electric
field from the atmosphere into the ionosphere is selected as
the seismogenic source, the positive disturbance in TEC is
formed as a result of the action of the additional eastward
electric field.