Changes in fof2 parameter in the ionosphere at mid and low latitude before earthquake

Abstract

This paper investigates the ionospheric variations before and after  earthquakes which  occurred in mid and low  latitude during 2011-2014. A running   median of the fof2 and associated inter- quartile range (IQR), upper bound (UB) and lower bound (LB) are employed as a reference for identifying abnormal signals during all four earthquakes. Our results reveal anomalous reductions and enhancements in the fof2 within 7 days before and after the earthquakes. The analysis during very quiet geomagnetic conditions is displayed to be a useful indicator of a forthcoming earthquake. A possible mechanism accountable for ionospheric anomalies associated with these   earthquakes is discussed.