Seismo-Ionospheric Variations during Strong Earthquakes Based on the Example of the 2010 Earthquake in Chile

Seismo-ionospheric variations during the strong earthquake on February 27, 2010 in Chile have been considered. An analysis of the ionospheric state has been performed using measurements based on a GPS satellite navigation system. The results of processing have shown that the decrease in the electron concentration on February 24, 2010 relative to the preceding day was from 24 to 35%. It has also been noted that, 3 days prior to the seismic event, a substantial drop in the rate of change of in the total electron content was observed near the epicenter zone for 1.5 h. It has been shown that, directly before the earthquake, instantaneous variations in the rate of change in the electron content by an order of value that exceeds normal background behavior was observed.