- 學位論文
從BATS及TAIGER測站記錄探討台灣地殼非均向性
Crustal seismic anisotropy observed beneath BATS and TAIGER broadband stations in Taiwan
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摘要
地殼的地震非均向性與沖積層理或大地應力所造成的地質線性構造有關。我們由分析台灣寬頻地震觀測網(BATS)及TAIGER計畫在台灣佈設寬頻測站所收集的波形記錄，研究台灣地區地殼的地震非均向性，並據以探討其與區域地體構造活動的關係。 空間上全島呈現幾種不同的非均向性型態：在變形前緣以西，快方向約略呈東西走向，與由最大水平壓應力軸方向所造成的裂隙方向相符。中央山脈以及海岸山脈量到的快方向大都與山脈走向平行，與斷層、葉理、節理、裂隙等微構造，甚至與高度變質區的礦物重結晶排列方向一致。中央山脈變質岩區所觀測的快方向較凌亂，這是因為在變質岩區岩體較破碎，易產生許多干擾波相所致，故分離時間並沒有因變質度變高而遞增。我們利用分離時間以及P波以及S波的走時差比值定義分離程度，並由分離程度的分析，我們發現台灣地區的非均向性強度主要集中於淺層的15 km以內。 與前人所做的台灣地區上地幔非均向性參數比較，發現地殼與地幔的剪力波分離時間差距過大，前人在中央山脈地區的上地幔觀測，分離時間可達2.4秒，但本研究所求得之最大分離時間為0.14秒，顯示地殼非均向性參數影響上地幔非均向性參數有限。
並列摘要
We examine broadband seismic waveforms recorded at both BATS and TAIGER stations deployed island-wide to investigate the crustal seismic anisotropy of Taiwan. Take advantage of the waveform cross-correlation method, we analyze the shear-wave splitting to extract anisotropic parameters, including the polarization of leading S wave and the split time (dt) between fast- and slow-S waves. The general patterns show EW fast direction to the west of the deformation front, which can be accounted for with aligned cracks induced by ambient tectonic stress. Beneath the Central Range and Longitudinal Valley to the east, the dominant fast directions are subparallel to the mountain strike, which agrees well with the lineation of foliations, fractures, and/or aligned minerals in these highly deformed regions. Many of the direct S waves observed in the Central Range were contaminated with later phases due to prevailing scatters beneath the Central Range that is composed of metamorphic rocks. Measurements along 3 EW trend linear arrays help further delineate the spatial variation of crustal anisotropy across the Central Range. We further estimate the normalized
參考文獻
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延伸閱讀
- 景國恩、許書琴、孔冠傑、陳芊如、趙荃敏（2013）。台灣地區動態座標框架立之先期研究－台灣現今之地殼變形模式。國土測繪與空間資訊，1(2)，17-35。https://www.airitilibrary.com/Article/Detail?DocID=P20130301007-201307-201603020035-201603020035-17-35
- 廖哲緯（2008）。台灣地區BATS地震矩張量震源解的品質評估及其在地震地體構造上的應用〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU.2008.01603
- Chang, C. P., Chen, K. S., Wang, C. T., Yen, J. Y., Chang, T. Y., & Lin, C. W. (2004). 應用雷達差分干涉技術觀測台灣區域性地殼變形. Terrestrial, Atmospheric and Oceanic Sciences, 15(3), 523-543. https://www.airitilibrary.com/Article/Detail?DocID=10170839-200409-15-3-523-543-a
- 陳力維（2014）。On the Near-surface Seismic Anisotropy of Taiwan〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU.2014.01845
- Chen, H. K., Sroda, P., Wu, F., Wang, C. Y., & Kuo, Y. W. (2013). Seismic Anisotropy of the Upper Crust in the Mountain Ranges of Taiwan from the TAIGER Explosion Experiment. Terrestrial, Atmospheric and Oceanic Sciences, 24(6), 963-970. https://doi.org/10.3319/TAO.2013.07.30.01(T)