淺部地層波速測勘方法測試與比較–以臺灣為例

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Title:	淺部地層波速測勘方法測試與比較–以臺灣為例
Authors:	賴翔威;Lai, Hsiang-Wei
Contributors:	地球科學學系
Keywords:	頻散曲線;速度構造;空間自相關法;多頻道表面波震測;折射震測;Dispersion Curve;Velocity Structure;SPAC;MASW;Seismic Reflection Method
Date:	2024-08-19
Issue Date:	2024-10-09 15:39:42 (UTC+8)
Publisher:	國立中央大學
Abstract:	本篇研究嘗試使用空間自相關法（Spatial Autocorrelation Method, SPAC 法）、多頻道表面波震測法（Multichannel Analysis of Surface Waves, MASW 法）、折射震測（Seismic Refraction Method）三種方法進行分析，並與本研究團隊先前使用的頻率波數法（Frequency–Wavenumber Method, FK 法）所得的頻散曲線，以及國家地震工程研究中心（National Center for Research on Earthquake Engineering, NCREE）開放的懸盪式速度井測（PS logging）資料進行比較。由於主動式測量（PS logging、MASW 法、折射震測）與被動式測量（SPAC 法、FK 法）之間的限制，微地動陣列與主動式 MASW 法對於深度的解析能力差距很大，某些測站的微地動陣列測深甚至超過 MASW 法的十倍。因此對使用上述兩種方法得到的頻散曲線做了測試，嘗試將頻散解析頻率接近或重疊（overlap）的頻散曲線結合，用以擴展頻散曲線的解析頻寬。在使用頻散曲線計算速度構造時需格外小心，因為在底部S波波速上升過快的情況下，可能會出現速度構造低估的問題。這是由於量測到的相速度存在上限，無法對頻散曲線做出超出此結果的解釋。對於使用 MASW 量測資料進行折射分析的成果含有較多誤差，但由於方法本身幾乎只能獲得簡單兩層的速度模型，PS logging 則是連續的速度資訊。除了折射震測的結果有較多誤差，SPAC 法與 MASW 法各自都在非極端場址條件（山腳下、高山氣象站及速度變化劇烈區域）均取得了良好結果。希望本研究能成為未來速度構造測量的參考資料。 ;This study analyzed three methods: the Spatial Autocorrelation Method (SPAC), the Multichannel Analysis of Surface Waves (MASW), and the Seismic Refraction Method. The results will be compared with the dispersion curves from the Frequency–Wavenumber Method (F-K Method) used in our laboratory and open PS logging data from the National Center for Research on Earthquake Engineering (NCREE). I also tested the dispersion curves obtained using SPAC and MASW methods and attempted to combine those with similar or overlapping frequencies ranges. However, caution is needed when using dispersion curves to calculate velocity structures due to the occasional underestimation. This underestimation is caused by the upper limit of the measured phase velocity, which limits our interpretation. The MASW refraction analysis results contained significant errors, mainly because the method can usually only obtain a simple two-layer model, and downhole measurements rarely start directly from the surface (at a depth of ≤ 2m), making it difficult to determine which method’s results are more accurate or to discuss potential improvements. Despite the errors in the seismic refraction results, the SPAC and MASW methods produced good results under non-extreme site conditions (such as at the foot of mountains, alpine meteorological stations, and areas with rapid velocity changes). This study aims to serve as a reference for future velocity structure assessments.
Appears in Collections:	[Graduate Institute of Geophysics] Electronic Thesis & Dissertation

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