大部份的山崩災害常與地表崩積土層或地下岩層的水飽和率有密切的聯結，且降雨也是個影響山崩災害的重要因素。藉由地球物理方法中的地電阻影像法，在長時間且穩定的監測中可以更了解現地的土壤或岩石隨時間變化的過程，並結合Archie’s Law以連結材料的電阻率與含水量之關係。 因此本研究利用時序地電阻影像法於台灣宜蘭太平山蘭台地區的山崩潛勢區域進行監測，並呈現地下材料的相對水飽和度隨時間的改變。本地電阻影像法測量使用一全自動的遠端地電阻量測系統(R2MS)，並採用非傳統的混編陣列每日定時蒐集電阻資料，本研究據此分析了自2019年至2021年於宜蘭太平山蘭台地區的監測資料。透過長期且穩定的地電阻監測，觀察到降雨事件對於地下電阻率結構的改變。結合岩心資料與電性結構進一步將電阻率影像進行分區，並對每個區域之電阻率取其中位數來代表該區域電阻率變化趨勢，細化在不同時間、空間尺度的地下電阻率結構探討。 對於不同的地質材料雨水滲透至地下需要的時間也不同，對應時段的降雨不會立即造成地底深處的電阻率改變，因此本研究將降雨劃分為數段雨場以利分析並挑選出四個示範案例。這些案例之電阻率剖面隨降雨的變化可能與本研究區域的相對水飽和度變化有關，並且暗示著降雨入滲的過程。本研究也觀察到伴隨滑動事件出現的電阻率上升和下降層位。由此可知，高頻率施測的時序地電阻影像法能提供豐富的地下資訊，期望未來能在山崩預警系統中扮演重要的角色。;Water saturation in the bedrock or colluvium is highly related to most landslide hazards, and rainfall is likely a crucial factor. The dynamic processes of onsite rock/soil mechanics could be revealed via monitoring using the electrical resistivity tomography (ERT) technique and Archie’s law. This study aims to demonstrate water saturation changes over time using time-lapse electrical resistivity images, providing a powerful method for monitoring landslide events. A fully automatic remote resistivity monitoring system was deployed to acquire hourly electrical resistivity data using a nontraditional hybrid array in the Lantai area of Ilan Taiping Mountain in Northeast Taiwan from 2019 to 2021. Six subzones in the borehole ERT images and a drill core were combined to examine the resistivity variations on temporal and spatial scales, as well as possible pathways of the groundwater. Two representative cases of inverted electrical resistivity images varying with precipitation may be correlated with water saturation changes in the studied hillslope, implying the process of rainfall infiltration. The electrical-resistivity-decreased and increased layers are also observed to be accompanying with sliding events. Accordingly, we suggest that high-frequency time-lapse ERT monitoring could play a crucial role in landslide alerts.
