由表面波資料探討台灣及鄰近區域之地殼速度側向變化

Lateral Variations of Crust under the Taiwan Region from Surface Wave

翁偉哲(Wei-Jhe Weng)

指導教授 ： 余貴坤 ； 顏宏元

國立中央大學/地球科學學院/地球物理研究所/碩士(2006年)

摘要

利用週期5~40秒的表面波頻散資料研究台灣及鄰近區域地殼速度構造，一共採用114個地震220筆地震資料來研究。
初步的群速頻散曲線可發現台灣存在南北向的側向變化，以0.47∘Ⅹ 0.47∘的網格做分區，利用純路徑法求出每個區塊的區域化群速，繪製出台灣及鄰近區域的群速分佈圖，在分區逆推出地下的S波速度，S波速度構造淺層的部分與群速的分佈類似，淺層沉積盆地分部與布蓋重力異常高低區分佈相當一致，有明顯的側向變化，與區域的變質度岩性組成有關。
由垂直剖面可看出台灣東部板塊碰撞的影像，台灣西部北港高區的形貌也相當清楚。由同緯度的垂直剖面，台灣可能存在的速度不連續面，分別在10公里與20公里，由台灣海峽向西部麓山帶變深。

關鍵字

雷利波 ； 台灣地區 ； 側向變化

並列摘要

This study is use BATS date calculate the three dimensional shear wave velocity structure of the crust under the Taiwan region. First use PMF to get group velocity dispersion of fundamental mode Rayleigh waves. Then, block inversion method was applied to get regionalized group velocity for each block of the research area. Then, surface wave inversion method was applied to invert the shear wave velocity of the each block from regionalized the group velocity. Finally, the shear wave velocity structure of each block is combined to form the three dimensional shear wave velocity structure of the crust under the Taiwan region. The result shows the velocity structure of Taiwan area has significant lateral heterogeneity. The velocity structure shows exist horizontal velocity discontinuity about 10 km and 20 km. Velocity discontinuity has a trend of eastward thickness.

並列關鍵字

Rayleigh wave ； Dispersion ； Taiwan area

參考文獻

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