預測地震之發生對防災科技而言相當關鍵。根據多年來之研究，位於板塊邊界花東縱谷之池上斷層有機會成為探討斷層潛移與地震活動關聯性研究之最適場所。為瞭解地下流體與潛變間之關聯性，九十六與九十七年度已於錦園場址進行了一系列調查(地形分析、地表調查、電阻探測、鑽孔岩心)、監測以及人為擾動(抽注水)之水力-力學偶合試驗。根據活動變形帶中孔隙壓力變化觀測結果，活動變形帶的孔隙水壓變化明顯較劇烈，推測此一異常現象可能與材料受壓產生超額孔隙水壓有關。除此之外，根據重複性微水試驗，池上斷層錦園場址附近活動變形帶之水力傳導特性具有高度空間變異性以及隨時間變化而變化之趨勢。本年度計畫將重覆性微水試驗改成氣壓式進行，並增加試驗頻率，以進一步瞭解斷層潛變對水力特性之影響。同時，本研究將增設雨量計以及四組高精度地表傾斜計，以長期自動監測水力-力學偶合效應分析所需之資訊。最後，利用彈性孔隙介質理論，綜合解釋觀測物理量之變化，以瞭解孔隙水壓以及有效應力對斷層潛變行為影響所扮演之角色，並模擬池上斷層潛變行為。預期本研究成果對於池上斷層潛變行為之瞭解將產生重要貢獻。 ; Increasing the abilities for predicting earthquake is important for earthquake hazard mitigation. The long-term monitoring in Chihshang active fault provides a good opportunity to look inside the relationships between surface creeping behaviors and earthquakes. Some interesting phenomena do reveal the mystery between surface creep of the Chihshang active fault and earthquakes. To better understand the role of fluids in the creeping of Chihchang fault, subsurface geophysical investigation, in-situ hydraulic tests and long-term pore water pressure, and deformation monitoring were conducted in 2007. Pore pressure variation in the active deformation zone of Chihshang fault was monitored in hydraulic observation wells and Casagrande type piezometers. In the active deformation zone, significant fluctuation of the pore pressure was observed. Besides, high spatial and temporal variability of hydraulic properties was observed utilizing a repeated slug test. In addition, surface titling and ground water table in the observation wells were monitored during pumping and injection tests during 2007 in the Chinyuan site. The surface tilting is well correlated to the pore pressure variation caused by pumping and injecting. Long term monitoring of the surface titling, pore pressure and rainfall (natural disturbance) is valuable to further characterize the geology and hydrogeology condition of the tested site. The hydro-mechanical response induced by rainfall can help us to identify the hydro-mechanical behavior of the active deformation zone near Chinyuan site. These data, together with the hydro-mechanical model, are essential to explore the mechanisms of surface creeping of the Chihshang fault. This research proposed a long-term monitoring plan for exploring the hydro-mechanical behavior of Chihshang active fault in Chinyuan site. The influence of the creeping fault on the hydraulic properties of sediments can be evaluated by repeated slug tests. Automatically recording the required rainfall, surface tilting, and pore pressure is proposed. Rain gage and four high resolution tiltmeters will be installed in Chinyuan site to measure rainfall and the small variation of the surface tilting. Numerical method will be utilized to explore the role of pore pressure, as well as the role of effective stress, on the surface deformation observed in Chinyuan site. It is anticipated that the results from the proposed study will largely enhance the ability for interpreting the relation between earthquake and creep phenomenon of an active fault. ; 研究期間 9808 ~ 9907
