International Science Community Association Research Journal of Recent Sciences 2277 - 2502 1 1 2012 January 2 Study of Ionospheric Perturbations during Strong Seismic Activity by Correlation Analysis Method 2 9 EN Gwal A.K. 1 Space Science Laboratory, Department of Physics Barkatullah University Bhopal-462026, INDIA Jain SantoshKumar 2 Panda Gopal 3 Gujar Y.S. 4 Raghuwanshi S. 5 S.K. Vijay 6 > Research Paper 2011 10 6 2012 January 2 Present paper deals the variation in NmF2 (Maximum electron density of F2 layer) parameter by correlation technique at the time of strong seismic activity. We used Ionosonde data which installed at different locations for analysis purpose. We used two ionosonde receivers, where one is in the earthquake preparation zone and the other is out side of it. By correlation technique we calculate Auto Correlation Coefficient and Cross-Correlation Coefficient. Results of the study showed the anomaly in Correlation Coefficients related to NmF2 parameter few days before the seismic event. This fact can be regarded as precursory phenomena. The anomaly 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. This study may be beneficial for prediction of earthquake. Copyright@ International Science Community Association