Ionospheric Precursor Associated to the 2012 Sumatra Earthquake Observed over the Taiwan-Philippines Region using GNSS-TEC

The seismo-ionospheric coupling relationship has been analyzed and investigated in this study. Geomagnetic activity, disturbance time (Dst) index, and Kp index were acquired from OMNIWeb Data Explorer. From March 1 to April 13, 2012. The total electron content was archived from the three GNSS-IGS station; PIMO station in Quezon City, Philippines, TWTF station at Taoyuan, Taiwan and TMNL station from Hsinchu, Taiwan from the measurement of the International Centre for Theoretical Physics (ICTP). In order to eliminate the influence of the geomagnetic storm, we used the sliding interquartile range method. This paper observed that variations exhibited positive ionospheric TEC anomalies on the 6th and 14th day before the Sumatra earthquake. We found that the observed positive TEC anomalies on the 6th and 14th day by three stations were most likely caused by the Sumatra earthquake after removing ionospheric abnormalities induced by magnetic storms. In other words, the obvious TEC anomalies observed may be considered precursors to this earthquake.