Pre-seismic ionospheric anomalies of the 2013 Mw = 7.7 Pakistan earthquake from GPS and COSMIC observations

Abstract

The seismo-ionospheric anomalies may provide some insights about the earthquake. However, pre-seismic ionospheric anomalies are still challenging. In this paper, seismo-ionospheric anomalies are investigated before the September 24, 2013 (Mw = 7.7) Awaran (Pakistan) earthquake from GPS TEC (Total Electron Content) and COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) data. The TEC data are showing anomalies on September 21, 2013. The abnormality detected in the temporal data is about 10 TECU beyond the 30-day running median. The percentage deviation of the TEC anomaly on September 21, is 30% above the upper confidence interval. The anomalies prevail 5° in Latitude and 10° in Longitude over the epicenter. The spatial and temporal data of TEC showed anomalies in TEC from UT = 08 to UT = 12. In addition, the enhancement on September 21, 2013 is also very significant in COSMIC data. The results of COSMIC completely agreed with GPS TEC anomalies on September 21, 2013. The percentage deviation of the peak plasma frequency on September 21 is 5% of the normal distribution. The storm indices are quiet before and after the earthquake. The pre-sesimic ionospheric anomalies are most probably associated with the 2013 Mw = 7.7 Awaran (Pakistan) earthquake.