文摘
To quantitatively study the relationship between earthquakes and ionospheric total electron content (TEC) anomalies, 24 5.0鈥?lt;鈥塎s鈥?lt;鈥?.0 earthquakes in China from 2003 to 2013 were selected and the global ionosphere maps from the International GNSS Service 20 days before and after each earthquake were analyzed. Significant negative and positive total electron content anomalies were observed; the averages of the absolute anomalies before the earthquakes were higher than after the earthquakes. The anomalies were not all negative or positive 5 days before the earthquakes and were not continuous. Anomalous areas were found close to the epicenters in all the earthquakes at the time of the earthquake, showing vortex distributions. The absolute Dst and Kp indexes of the 7.0鈥?lt;鈥塎s鈥?lt;鈥?.0 earthquakes were more than 50 nT and 4, respectively, in the 20 days period before most of the earthquakes. Our study confirms the premise that extreme solar and geomagnetic activities may lead to earthquakes. This study also showed that the negative and positive TEC anomalies during Ms鈥?gt;鈥?.0 earthquakes are not continuous and regular. The TEC anomalies were not proportional to the earthquake magnitudes and all the anomalies on the day of the earthquake at the epicenters were not significantly higher or lower than on other days. Keywords Statistical analysis Seismo-ionospheric anomalies GPS TEC Ms鈥?gt;鈥?.0 earthquakes Sliding quartiles