使用震源機制逆推台灣地區應力分區狀況; Using Focal Mechanism to Invert the Stress Fields in the Taiwan Region

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题名:	使用震源機制逆推台灣地區應力分區狀況;Using Focal Mechanism to Invert the Stress Fields in the Taiwan Region
作者:	呂玉菀;Yu-Wan Lu
贡献者:	地球物理研究所
关键词:	應力分區;應力;震源機制;台灣;Taiwan;focal mechanism;stress
日期:	2004-06-30
上传时间:	2009-09-22 09:54:42 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本研究收集台灣地區震源機制解資料，進行大地應力逆推計算，企求劃分合理的應力均質區及探討各均質區的應力狀況。研究中蒐集品質較高的CMT法與波形逆推法所得的震源機制解為資料，分別利用Gephart逆推方法與Michael逆推方法求得各移動視窗的應力逆推結果，再依照各視窗所得結果進行均質區的圈劃，並加以適當的調整，以得到各個合理的應力均質區域。若兩種逆推方法所得差別較大，也使用Angelier逆推方法加以比較。進行移動視窗逆推分析時，將資料分為規模大於3者及規模大於4者兩組，分別進行分析及劃分應力均質區。結果發現，使用兩種資料分類，皆可將研究區域劃分為9-10個分區。由於資料量的大小差異，導致分區的範圍略有不同，但兩種分類所得的分區結果卻相近。各個分區細節皆有不同，但是大部分區域之最大主應力方位，皆符合菲律賓海板塊向西北擠壓歐亞板塊的方向。台東縱谷東側可以被劃分為一個完整的應力均質分區，而台灣西半部的最大主應力軸方位，由南較成東西向，越往北有順時針向北偏轉的效果產生。在宜蘭分區，因沖繩海槽的影響，其最大主應力軸呈現東北—西南走向的正斷層或橫移斷層的機制。 The purpose of this study is to find out the stress condition in different homogenous stress zones in the Taiwan region, by method of stress inversion using focal mechanism data. Numerous focal mechanism data have been collected from various literatures. The methodology of stress inversion was the orientation of principal stress axes with the 95% confidence regions estimated by the Gephart method and Michael method. If there is a discrepancy between the results of the two methods, the Angelier method was used for comparison. Our study area includes the whole island and extends to 30 km offshore. The range of hypocenter depth is 0 to 30 km. High quality focal mechanism data obtained from the centroid moment tensor and waveform inversion algorithm within this zone were collected . Two dataset were retrieved from the focal mechanism database, group one is those with magnitude greater than 3 and group two greater than 4 for more consistent data. The Taiwan region was firstly divided into 9 or 10 homogenous zones by adopting a criteria of misfit less than 6 degrees in the stress inversion scheme. The results in each homogenous area show that great majority of principle stress directions are consistent with the collision between the Philippine Sea Plate and the Eurasian Plate for the whole study zone. The eastern side of the Longitudinal Valley can be considered as a homogeneity of stress field. On the other hand, in Western Taiwan, the direction of most principal stress changes clockwise from E-W in the South to N in the North. In I-Lan, near the Okinawa Trough, transtensional faulting mechanism and more NE-WS maximum horizontal stress direction were found.
显示于类别:	[地球物理研究所] 博碩士論文

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