台灣地形海拔落差大、構造活動發達、地質脆弱，以及颱風與梅雨季帶來的大量降雨，使台灣頻繁發生坡地災害，並對人民的生命財產造成嚴重的損失，因此對不穩定邊坡進行有效監測及預警以減少坡地災害帶來之損失至關重要。本研究將使用環境噪訊互相關(ANCA)及水平垂直頻譜比法(HVSR)兩種被動式地球物理方法進行邊坡監測，前者計算出的速度變化率(dv/v)可用來推測各時段地質材料物理性質的狀態及變化，後者計算的 HVSR頻譜，可用來得到地層各時段共振頻率(主頻)的特徵及變化以推估邊坡地層界面的狀態及變化。本研究以嘉義縣竹崎鄉中心崙大規模崩塌潛勢區為例，包含五座地震測站，並使用資料品質最佳的CHL4測站為主要分析對象，以2024年全年及2025年上半年為主要探討時段，討論降雨與地下水位變化對邊坡地質材料物理性質的影響。
ANCA結果顯示，中心崙邊坡之速度變化率(dv/v)呈現明顯季節規律，乾季dv/v維持於0%附近，雨季則轉為負值，反映含水量增加導致波速下降之現象。雨季期間降雨事件的dv/v與最大日雨量(r=-0.591)相對於累積降雨量(r=-0.464)負相關性更高，顯示單次降雨強度相較累積雨量更能主導dv/v。另一方面HVSR分析顯示，中心崙邊坡CHL4測站處主要存在五個主頻，各主頻對應不同深度地層界面，並對降雨事件呈現相異特徵，深層主頻(f1)全年穩定，次深主頻(f2)隨降雨事件峰值微幅增加，中層主頻(f3、f4)多於雨季出現並於降雨事件時峰值明顯增加，反映飽和/非飽和介面變化。透過CHL4測站 HVSR曲線反演建立一維速度模型，確認f1、f2分別對應約71.5m與26.6m深之速度介面，與鄰近鑽井岩性介面結果接近。此外本研究探討2024年對中心崙邊坡造成崩塌的凱米颱風極端降雨事件，dv/v二十四小時移動平均下降至全年最低 -1.21%，HVSR f3、f4峰值不增反降，兩者可能共同指向邊坡地層整體飽和且地下水位接近地表之現象。於凱米颱風造成崩塌事件前，dv/v於十六小時前快速下降，f1於三小時前出現異常峰值上升，兩方法展現不同特徵崩塌前兆。ANCA與HVSR於乾季、雨季及極端降雨事件中觀測結果相互呼應，兩者用於邊坡監測具有互補性，dv/v反映地層整體波速變化趨勢，HVSR判識各深度界面的響應特徵，兩者結合能有效反映邊坡地質材料物理性質時序變化，具有成為邊坡監測與預警工具之潛力。

Taiwan's frequent landslides, driven by steep terrain, active tectonics, fragile geology, and heavy typhoon and Mei-yu rainfall, highlight the need for effective slope monitoring. This study applies Ambient Noise Correlation Analysis (ANCA) and Horizontal-to-Vertical Spectral Ratio (HVSR) at the Jhongsinlun large-scale landslide susceptibility zone, Chiayi County, using CHL4 station data from 2024 and the first half of 2025 to investigate how rainfall and groundwater fluctuations affect slope material properties.
ANCA reveals a clear seasonal pattern in dv/v: near 0% in the dry season, turning negative in the wet season. Wet-season dv/v correlates more strongly with maximum daily rainfall (r = −0.591) than cumulative rainfall (r = −0.464), suggesting intensity dominates velocity reduction. HVSR identifies five dominant peaks at CHL4: f1 (deepest) is stable year-round; f2 increases slightly during rainfall; f3 and f4 emerge in the wet season and amplify during events, reflecting saturated/unsaturated interface dynamics. Inversion confirms f1 and f2 correspond to interfaces at ~71.5 m and ~26.6 m depth, consistent with nearby borehole stratigraphy.
During Typhoon Gaemi, the 24-hour moving average dv/v reached an annual minimum of −1.21% while f3/f4 amplitudes anomalously decreased, jointly indicating near-complete saturation. Before the triggered landslide, dv/v declined rapidly 16 hours prior and f1 showed anomalous amplitude increase 3 hours prior, capturing precursory signals from complementary perspectives. ANCA and HVSR together provide mutually consistent, complementary observations, demonstrating their potential as integrated tools for slope monitoring and early warning.

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