Study of Ionospheric Perturbations during Strong Seismic Activity by Correlation Analysis Method

In this study, we report the variation in foF2 (critical frequency of F2 layer) parameter by correlation method at the time of strong seismic event. Ionosonde data installed at different locations were used for analysis purpose of four cases of earthquakes. Considering two ionosonde recorders, where one ionosonde is in the earthquake preparation zone and the other is out side of it. By correlation analysis method Karl's Pearson coefficients have been calculated. Results of the study showed the anomaly in the Karl's Pearson coefficient related to foF2 parameter, few days before the seismic activity. This fact can be regarded as precursory phenomena. The changes in the F-layer density may be interpreted as a result of associated seismic electric field generated by internal gravity waves. It may be due to the inflow of energy from the earth and then propagated upward which perturb the F-region of ionosphere. Hence, EB drift in the ionospheric region get changed. This study may be beneficial for prediction of earthquake.