摘要 本論文利用全球定位系統(Global Positioning System, GPS)地面接收機觀測電離層全電子含量(Total Electron Content, TEC)，統計分析1999-2008年全球143筆規模(M) ≥ 7.0地震期間電離層全電子含量的變化，並進一步探討不同的震源機制(focal mechanism)之異常現象。結果顯示震前7-5日期間電離層電子濃度異常減少的機會增大。此外，異常減少之現象以逆斷層與走向斷層地震最為顯著。 Abstract In this paper, we utilize the ground based GPS receivers to measure the total electron content (TEC), and statistically analyse the ionospheic TEC variations during the periods of 143 Magnitude ≥ 7.0 earthquakes occurred between 1999 and 2008. Furthermore, we explore the anomalous phenomena of the different focal mechanisms. The results show that the probability of anomalous decrease of ionospheric electron density could lift 7-5 days before the earthquake. In addition, the phenomenon of ionospheric decreased anomaly is most significant to the reverse fault and the strike-slip fault earthquake.
