Investigation of Ionospheric Anomalies in Relation to Earthquakes during High and Low Solar Activity Periods in Years 2002 and 2021

Abstract

The interaction between lithosphere and atmosphere allows us to recognize the effects of tectonic activity on the ionosphere layer. This indicates that TEC (Total Electron Content) anomalies in the ionosphere can be a precursor to earthquakes. Within the scope of this study, ionosphere changes in pre- and post- earthquake time series of two earthquakes with magnitudes of 7.9 Mw at solar maximum times which is in solar cycle 23, 2002 and 8.2 Mw at solar minimum times which is in solar cycle 25, 2021 were investigated. TEC changes in ionosphere were calculated using GPS (Global Positioning System) data of IGS (International GNSS Service) stations located within and outside the earthquake preparation area. Anomaly values in TEC changes were computed by applying the moving median method based on the interquartile range to time series. To determine whether the anomalies were caused by space weather conditions, the indices of solar activity (F10.7), geomagnetic storm (Kp), geomagnetic field (B) and disturbance storm time (Dst) were evaluated, and correlation coefficients (?) between them and TEC anomalies were calculated. As a result of the study, it was observed that TEC values and anomalies in the earthquake which occurred during the solar maximum time were quite higher than those in the earthquake which took place during the solar minimum time. TEC anomalies which happened independently of space weather conditions prior to earthquakes were accepted as earthquake precursors.