Investigation of relation between the variation of some ionospheric parameters with earthquakes for magnitude M > 5.0

In this study, relationship betwen ionospheric F2 region critical frequency (foF2) data were taken from 6 iosonda stations located in that area with 24 earthquakes M > 5.0 and D > 40km (M = magnitude, D = depth) occurred in Japan between 1975 and 2011 were studied statistically. Correlation, Standard Deviation (SD), Interquartile Range (IQR) and Fluctuation Analysis (FA) were applied on the data. In order to make a correct interpretation of perturbations causing changes in ionosphere, obtained results were compared with variations of some indices (F10.7, USGS, Dst, Kp, Ap) showing the activities of Solar and geomagnetic storms. For all earthquakes at the variations occured in critical frequency, Although there is no direct connection between the depth and the magnitude of the earthquake, the distance from the station to the center of the earthquake was observed to be significant. However for similar-magnitude earthquakes, it can be expressed that variations on the shallow earthquakes is the greater. It seen that besides position of the earthquakecenter and stations, tectonic plates on the area occured earthquakes were effective. On earthquakes occured movement of tectonic plates on that region and eastern regions of Japan, while impacts and variations are more, on the west regions they are very small. In many of the earthquakes, on the stations near the earthquake center, variations depending on the Solar and geomagnetic activities are less severity compared to those away. On the days occured perturbations in foF2, besides depending on the Solar and geomagnetic activities, especially when these activities were low/quiet, variations thought to be due to the activity were seen. In some earthquakes, there are significant diffreneces between stations that provide data for earthquakes. Results of statistical analysis for each earthquakes show consistency in general despite some contradictions about their days. However, important differences exist for some earthquakes data. While Fluctuation Analysis doesn?t show variations connected to the Solar and geomagnetic activities so much, other analysis exhibit results associated with these activities.