A statistical investigation of pre-earthquake ionospheric TEC anomalies

:Previous researches show that the total electron content (TEC) in the ionospheric exhibits anomalous disturbances a few days or hours prior to earthquakes. The paper used TEC data from Internet GPS Service (IGS), and examined 50 earthquakes of magnitude Ms ≥ 7.0 during 2007–2009 worldwide. The result shows significant anomalous increases and decreases about 7 days prior to 94% of the earthquakes.