A Study Of Seismo-Ionospheric GPS TEC Anomalies Over Epicenters Of Strong Earthquakes

Among natural disasters to human beings, an earthquake is on top of the list which causes the most serious life and property loss. Due to the complexity of earthquake, it is difficult to accurately yield the three key elements of the earthquake prediction at present. It is known that the earthquake prediction is a worldwide issue. The precursory study is essential approaches for earthquake predictions. In recent years, a study of seismo-ionospheric anomalies offers a new way for the earthquake prediction. Signatures and mechanisms of the observed anomalies might provide important information to the three elements of earthquake prediction. In this thesis, 405 earthquakes, including worldwide Ms≥7.0 earthquakes and regional Ms≥6.0 earthquakes occurred in China, Taiwan, Indonesia, Japan, and west coat of America, from Jan. 1999 to Oct. 2007 are examined. Data extracted from the IGS (International GPS Service) are used to analyze anomalies of the ionospheric total electron content (TEC) appearing over the epicenters of the both global and regional earthquakes. The data including and excluding magnetic storms and earthquakes located in various depths, latitudes, and longitudes have been statistically investigated for understanding anomalies associated with the three elements.Results of the global 151 Ms≥7.0 earthquakes show that ionospheric TECs instead of increasing significantly decrease day 1-5 before the earthquakes.Meanwhile, appearances of the anomalies associated with the 405 Ms≥6.0 earthquakes occurred in China, Taiwan, Indonesia, Japan, and west coat of America are found to be generally similar except the anomalies appearing either day 1-6 or 1-5 before the earthquakes. The overall results demonstrate that the earthquake location, depth, latitude, and longitude, might play important roles for the appearance of the seismo-ionospheric anomalies.