Variations of foF2 prior to earthquakes

Earthquakes are a kind of rapid and huge energy release process of the Earth's internal energy. The changes associated to this energy release affect the atmosphere and ionosphere around the earthquake zone. In this study, the ionospheric foF2 can be used to analyze the change in the foF2 before and during earthquakes. The earthquakes in Sumatra in 2007 and in Italy in 2002 were chosen in this analysis. The raw data taken from ionosondes were used to measure the virtual height of the foF2. The comparison analysis of the foF2 was done by observing the values before and during the earthquakes on various dates and times when the earthquakes occurred. The results show that an earthquake does affect the ionospheric value of the foF2, where the foF2 value is lower than the ordinary daily value. The value decreases two hours before the earthquake and remains at a low level of 2.7 MHz during the earthquake. This has been shown by an analysis that was conducted at different times, dates and locations.