Modeling the pre-earthquake electrostatic effect on the F region ionosphere

This paper presents the results of modeling the ionospheric effect of the seismogenic electrostatic field (SEF) seen at the earth's surface as a perturbation of the vertical atmospheric electrostatic field in the earthquake preparation zone. The SEF distribution at ionospheric altitudes is obtained as an analytical solution of the continuity equation for the electric current density. It is shown that at night, the horizontally large scale SEF can efficiently penetrate into the ionosphere and produce noticeable changes in the horizontal distribution of the F region electron density. The results suggest that the seismogenic electrostatic field could be a possible source for the ionospheric variations observed over Taiwan before the strong Chi Chi earthquake of September 21, 1999.