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.