The grid search algorithm of tectonic stress tensor based on focal mechanism data and its application in the boundary zone of China, Vietnam and Laos

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• 作者：Yongge Wan ; Shuzhong Sheng ; Jichao Huang ; Xiang Li ; Xin Chen
• 关键词：stress tensor ; grid search ; focal mechanism ; uncertainty
• 刊名：Journal of Earth Science
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：27
• 期：5
• 页码：777-785
• 全文大小：1,385 KB
• 刊物主题：Earth Sciences, general; Geotechnical Engineering & Applied Earth Sciences; Biogeosciences; Geochemistry; Geology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1867-111X
• 卷排序：27

文摘

Stress field plays a key role in geodynamics. In this study, an algorithm to determine the stress tensor and its confidence range from focal mechanism data by using grid search method was proposed. The experiment uses artificial focal mechanism data which were generated by extensional, compression and strike-slip stress regime and different level of noise, shows that the precision of the estimated stress tensor based on this algorithm is greatly improved compared with traditional algorithms. This algorithm has three advantages: (1) The global optimal solution of the stress tensor is determined by fine grid search of 1º×1º×1º×0.01 and local minimum value is avoided; (2) precision of focal mechanism data can be considered, i.e., different weight of the focal mechanism data contributes differently to the process of determining stress tensor; (3) the confidence range of the determined stress tensor can be obtained by using F-test. We apply this algorithm in the boundary zone of China, Vietnam and Laos, and obtain the stress field with SSE-NNW compressive stress direction and NEE-SWW extensional stress direction. The stress ratio is 0.6, which shows that the eigen values of the stress tensor are nearly in arithmetic sequence. The stress field in this region is consistent with the left-lateral strike slip of the Dienbien-Lauangphrabang arc fault. The result will be helpful in studying the geological dynamic process in this region.