喬凌雲Chiao, Ling-Yun臺灣大學:海洋研究所方慧圓Fang, Hui-YuanHui-YuanFang2010-05-062018-06-282010-05-062018-06-282009U0001-1208200914185300http://ntur.lib.ntu.edu.tw//handle/246246/181247摘要 我們利用周遭雜訊法研究沖繩海槽淺部岩圈，因為此法不受地震與測站之間時空幾何分布的限制，只在乎測站之間分布的位置。我們計算由BATS、F-net和IES-OBS提供之共19個寬頻地震記錄站所記錄垂直方向上之長時間連續記錄的交互相關函數，得到測站間表面波傳遞的格林函數。把所有天數資料的疊加訊號與每20天疊加一次的訊號做相關係數的計算，挑選出較好品質的格林函數重新疊加，以不同的頻段(10~50秒之間)對其做窄頻濾波並計算其群速度值。利用得到的頻散曲線以三種不同的逆推的方法得到此區的層析成像、模型解析矩陣與模型變異數，並且比較其不同。最後我們佈放虛擬的海底地震儀，觀察其解析函數以及模型變異的空間變化，來探討如何佈放可使我們最能有效的描繪波速構造。Abstract We use ambient noise technique(ANT) to study the shallow lithosphere of Okinawa Trough, because ANT would not be limited by the distribution of earthquakes and stations. It depends only critically on the geometrical spread of stations. Vertical-component time-series recorded from 19 broad-band stations have been correlated with one another to yield estimated Green’s functions. We sort out data if the coefficient correlation between all-stacked and per 20 days-stacked record that are over an a prior assigned threshold. We then stack again to get higher quality Green’s function. We filter them by a narrow band that is concentrated within 10 to 50 s period to compute the group velocity maps in order to execute the tomography, and obtain the inverse model, the model resolution, and the model covariance matrix by three ways of inversion. In the end, we discuss the ideal pattern of OBSs deployment enhance our understanding of the Okinawa Trough.目錄次試委員會審定書..................................................................................................................................I文摘要.....................................................................................................................................................II文摘要....................................................................................................................................................III錄.............................................................................................................................................................IV目錄........................................................................................................................................................VI目錄......................................................................................................................................................VIII一章 序論............................................................................................................................................1 1.1 簡介周遭雜訊法以及其與傳統地震學方法的優劣..................................................1 1.2 研究區域、目的與動機.......................................................................................................1二章 基本原理、資料與資料處理............................................................................................3 2.1 研究方法基本原理...............................................................................................................3 2.2 資料來源..................................................................................................................................5 2.3 資料處理..................................................................................................................................5 2.3.1 降低取樣率及移除儀器響應...........................................................................9 2.3.2 濾波、資料連接及切齊.....................................................................................9 2.3.3 正規化.......................................................................................................................9三章 資料篩選與逆推方法........................................................................................................13 3.1 資料篩選.................................................................................................................................13 3.1.1 三個波長的限制.................................................................................................13 3.1.2 利用相關係數挑選資料...................................................................................13 3.2 頻散分析.................................................................................................................................15 3.3 逆推方法.................................................................................................................................15 3.3.1 區域格點有限參數化.......................................................................................18 3.3.2 奇異值分解與設定門檻值.............................................................................18 3.3.3 傳統正則化..........................................................................................................21 3.3.4 捲積消制法..........................................................................................................23 3.3.5 多重尺度有限參數法........................................................................................24四章 逆推結果與虛擬海底地震儀佈放試驗........................................................................25 4.1 逆推結果..................................................................................................................................25 4.1.1 最適模型解...........................................................................................................25 4.1.2 層析成像、模型解析矩陣與模型變異數.................................................26 4.2 時空監控.................................................................................................................................37 4.3 虛擬海底地震儀佈放試驗...............................................................................................37 4.3.1 全面佈放...............................................................................................................37 4.3.2 部份佈放...............................................................................................................40五章 結論..........................................................................................................................................45考文獻..................................................................................................................................................46application/pdf7105454 bytesapplication/pdfen-US表面波層析成像沖繩海槽周遭雜訊法交互相關函數tomographyOkinawa Troughambient noise techniquecross-correlationthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/181247/1/ntu-98-R96241305-1.pdf