Physical mechanism of the electric field amplification in the mid-latitude ionosphere over active tectonic faults

The issue of seismo-ionospheric anomaly is noticeable increasingly. In this paper we use a model for the generation of the electric field in the ionosphere by an external current on the Earth´s surface to calculate the electric field in the ionosphere over the forthcoming earthquake preparation area. At the selected parameters the horizontal electric field in the ionosphere reaches ~10mV/m, while the magnitude of the vertical electric field disturbance on the Earth´s surface is limited by 100V/m. Then we discuss the influence of the anomalous electric field on the ionosphere characteristics. It leads to a perturbation in the critical frequency of F2 layer (foF2). We find the result is consistent with the observations.