近來有證據顯示大地震前會有超低頻電磁波釋放至地表進而干擾大氣離子濃度，而隨著全球衛星導航系統技術的發展，高採樣率GPS 應用於大氣與地震關聯現象測量也愈趨成熟。本研究以20 HzGPS 資料觀察2010 年3 月4 日高雄甲仙大地震（ML 6.4）前十四天的訊號變化情形以分析電離層濃度在地震前的異常跡象，同時也將地震時的GPS 位移訊號與測震儀資料做比對。研究結果發現在地震前三天開始低解析度的GPS 載波相位變化情形反映出較低的全電子含量，而當訊號解析度提升之後由於雜訊的增加使變化情形不顯著，將高頻訊號分離出後發現在此次地震前無明顯變化特徵。而GPS 測量結果與同震位移測震儀成果相似率極高，測量之頻譜特徵除在極低頻（< 0.002 Hz）的部分GPS 有較多雜訊外，對於主震頻率的位移測量均能獲得相近的成果，證實以高採樣率GPS 作強地動位移量測之可行性，並且提供了不受強地動儀響應干擾之真實運動模式。

There is evidence shows large earthquakes will release ultra-low frequency electromagnetic wave to the surface and thus disturb the concentration of ion within atmosphere recently. With the development of global navigation satellite system (GNSS) technology, applications of using high-rate GPS signal in atmospheric perturbation detecting and coseismic displacement measuring are also increased. In this study, 20 Hz GPS data was used to observe the signal variations of ionosphere concentration prior to 14 days of Kaohsiung Jiaxian earthquake (ML 6.4), March 4th, 2010, to analyze the possible abnormal signs. GPS displacement data with kinematic filter technique is used to compare with seismograph data. Results showed that three days before the earthquake ruptured a lower value of total electron content (TEC) in low-data-resolution carrier phase variations have found. After the data resolution is enhanced, there is no significant change under such circumstances due to the increasing of signal to noise ratio. After extracting the high-frequency signals, we found that there is no significant change prior to the earthquake. On the other hand, the GPS filtered displacement signal and signal of seismograph are highly similar except the GPS has more noise in very low frequency part (< 0.002 Hz). The measurements of data from main frequency of earthquake are very similar to each other within this study, which proved the feasibility of using high-rate GPS for strong motion displacement measurement, and provides the true ground motion without interference from the instrument response of seismograph.

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