台灣東部成功地區於2003年12月10日發生地震矩規模6.8之地震，為1951年來最強烈的一次。本研究選定安通溫泉區內之吉祥溫泉農莊之D1監測井，及安通溫泉飯店之地下水溶解氣體監測井(原為工研院500米探勘井)，作為觀測地震前兆之監測井。監測井距離2003年成功地震震央24公里處，鄰近池上斷層，為現今歐亞板塊及菲律賓海板塊之交界處。
　　安通溫泉地質構造是由含破碎裂隙玄武岩所組成，被泥岩包圍。地震前岩體膨脹產生新裂隙，地下水補注到新裂隙的速度遠低於新裂隙產生的速度，引起溶解於地下水中的氡氣逸出水相至新裂隙中的氣相，可解釋震前水氡濃度的異常下降。本研究自2011年1月起同步監測溶解在地下水中的水氡及甲烷氣體。觀測到地下水水氡及甲烷之濃度同步變化及數據進一步佐證水氡逸出水相的物理機制。

The 2003 Chengkung earthquake of magnitude (MW) 6.8 on December 10, 2003 was the strongest earthquake near the Chengkung area in eastern Taiwan since 1951. The Antung radon-monitoring station was located 24 km from the epicenter.
The Antung hot spring is situated in a basaltic fractured block inside mudstone. Under such geological conditions, we made a hypothesis that the dilation of rock masses was produced at a rate faster than the recharge rate of pore water and gas saturation developed in rock cracks preceding the earthquake. In-situ radon volatilization into the gas phase may explain the groundwater radon anomalous decrease precursory to earthquakes. Since January 2011, we started to monitor groundwater-dissolved radon and methane. The mechanism of in-situ radon volatilization has been corroborated by the simultaneous concentration changes in groundwater-dissolved radon, methane, and ethane observed during the above time period.

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