利用中国地震科学台阵研究青藏高原东南缘地壳各向异性:第一期观测资料的剪切波分裂特征

doi:10.6038/cjg20151116

摘要
图/表
参考文献
相关文章 (15)

全文: PDF (8234 KB) HTML (1 KB)
输出: BibTeX | EndNote (RIS)

摘要中国地震科学台阵第一期(2011-2013年)布设在南北地震带南段,本研究利用中国地震科学台阵布设在云南及相邻地区的部分流动台站记录到的2011年6月至2013年3月的数字地震波形资料,开展地壳各向异性分析.本文使用剪切波分裂系统分析方法(SAM方法),获得了研究区内67个台站的剪切波分裂参数.研究结果表明,受到云南及周边地区复杂的构造、应力环境和纵横交错的断裂分布的影响,该地区快剪切波偏振方向(PAZ)整体上显示出NNE向和NE向的优势取向,但在空间分布上比较复杂,虽然大部分台站的PAZ与构造应力场方向一致,但部分断裂附近台站的PAZ受到断裂的影响.结果显示,本研究区内不同区域的PAZ有一定差异性.本研究划分了5个子区,西部3个不同区域的PAZ从北到南分别为NNW向、近N-S向和NE向,有顺时针旋转的趋势,而东部的2个区域PAZ分别为NEE向和NNW向.研究证实,青藏东南缘地区的地壳各向异性空间分布虽然非常复杂,但大体上与区域内的主压应力的方向和断裂分布相关.

	服务

	把本文推荐给朋友
	加入我的书架
	加入引用管理器
	E-mail Alert
	RSS
	作者相关文章
	太龄雪
	高原
	刘庚
	肖卓

关键词 ：青藏高原东南缘, 地壳各向异性, 剪切波分裂, 快剪切波偏振方向(PAZ), 慢剪切波时间延迟(δt), 主压应力, 中国地震科学台阵

Abstract：The southeastern margin of Tibetan Plateau has relatively complex tectonic movement and strong tectonic deformation, which grows deep fracture and shattered crust. In order to investigate the crustal deformation mechanism in this region, the study uses data obtained from temporary stations in the south part of North-South Seismic Belt set up under the project ChinArray Phase I from June 2011 to March 2013, to compute the seismic anisotropy applying Systematic Analysis Method of shear-wave splitting (SAM method).#br#SAM method is a comprehensive analysis technique for crustal shear-wave splitting, and it divides into three principal phases: calculation of cross-correlation function, time delay correction and polarization analysis check. Firstly, intercept two horizontal components of the waves, and rotate them to calculate the correlation function. When the correlation function reaches a maximum value, the corresponding rotation angle and time delay can be treated as the preliminary polarization of fast shear-wave (PAZ) and time delay of slow shear-wave (δt). Then, according to the preliminary result, do the time delay correction and polarization analysis check. When the polarization pattern is close to the linear after the time delay correction, the calculation results are acceptable and will be the final result.#br#We analyzed 826 data recorded from 67 stations of ChinArray. According to the regional distribution of stations, faults and the result of shear-wave splitting, we divided the study zone into 5 sub areas, A, B, C, D and E. Area A locates at northwest of the study region, including 21 stations. PAZ in this area are relatively complicated, which trend NW, NE, and NEE; area B is on the west of the study region, and also includes 21 stations, PAZ in this area strike to nearly N-S or NEE; area C locates at southwest of the study region, and includes 9 stations, PAZ of most stations are in direction of NE; area D is on the northeast of the study region, and contains 5 stations, PAZ in this area strike to NE or NW; area E locates at northeast of the study region, and includes 11 stations, PAZ of most stations are in direction of NNW. The PAZ in area A, B and C which locate at west of study region, are in direction of NNW, nearly N-S and NE from north to south, which show a trend of clockwise rotation. While D and E area at eastern part strike to NEE and NNW respectively, PAZ in area D may be influenced by the NE strike fault in the region, and PAZ in area E are consistent with the tectonic stress field, also may be affected by the mass faults strikes to N-S or NW. PAZ at most stations strike to the direction of NNE and NE, consistent with the direction of tectonic stress field, but at some stations near faults are affected by the strike of the faults. The result shows that PAZ is varied with the different areas.#br#Complex tectonics and crisscrossed distributions of faults results in complex PAZ spatial distribution. PAZ at most stations are consistent with the direction of tectonic compressive stress field, while at other stations, they are consistent with the direction of fault strike. This study finally obtained more regional distribution details than the early results such as Shi et al.(2006; 2012), who used the permanent stations. However, due to the complicated geological features, characteristics of shear-wave splitting in the crust in this region still need more data and studies to sustain and verify.

Key words： Southeastern margin of Tibet plateau Crustal seismic anisotropy Shear-wave splitting Polarization of fast shear-wave(PAZ) Slow shear-wave time delay(δt) Principal compressive stress China Seismic Array (ChinArray)

收稿日期: 2015-01-15

PACS:

P315

基金资助:国家自然科学基金(41174042)和地震行业科研专项(201008001,201308011)共同资助.

作者简介: 太龄雪,女,1982年生,中国地震局地震预测研究所助理研究员,从事地震各向异性研究.E-mail:tailingxue@163.com

链接本文:

http://www.geophy.cn/CN/10.6038/cjg20151116 或 http://www.geophy.cn/CN/Y2015/V58/I11/4079

Chang L J. 2006. Constraining the dynamic characteristics of lithosphere and asthenosphere in Mainland China and its adjacent regions using GPS, Quaternary fault slip rates and shear wave splitting data[Ph.D.Dissertation]. Beijing: Institute of Geophysics, China Earthquake Administration, 133.
Cochran E S, Li Y G, Vidale J E. 2006. Anisotropy in the shallow crust observed around the San Andress Fault before and after the 2004 M6.0 Parkfield earthquake. Bull. Seismol. Soc. Am., 96(4B): S364-S375.
Crampin S, Peacock S. 2005. A review of shear-wave splitting in the compliant crack-critical anisotropic Earth. Wave Motion, 41(1): 59-77.
Cui X F, Xie F R, Zhang H Y. 2006. Recent tectonic stress field zoning in Sichuan-Yunnan region and its dynamic interest. Acta Seismologica Sinica (in Chinese), 28(5): 451-461.
Gao Y, Wang P D, Zheng S H, et al. 1998. Temporal changes in shear-wave splitting at an isolated swarm of small earthquakes in 1992 near Dongfang, Hainan Island, southern China. Geophys. J. Inter., 135(1): 102-112.
Gao Y, Liang W, Ding X, et al. 2004. Variational characteristics of shear-wave splitting on the 2001 Shidian Earthquakes in Yunnan, China. Acta Seismologica Sinica (in Chinese), 26(6): 576-582.
Gao Y, Wu J, Fukao Y, et al. 2011. Shear-wave splitting in the crust in North China: stress, faults and tectonic implications. Geophys. J. Int., 187(2): 642-654.
Gao Y, Shi Y T, Wu J, et al. 2012. Shear-wave splitting in the crust: regional compressive stress from polarizations of fast shear-waves. Earthquake Science, 25(1): 35-45.
Gao Y, Zheng S H, Sun Y. 1995. Crustal crack anisotropy in Tangshan area. Acta Seismologica Sinica (in Chinese), 17(3): 283-293.
Li B J, Qin J Z, Qian X D. 2002. Shear-wave splitting of the aftershocks for the 1995 earthquake of Yunnan Wuding. Journal of Seismological Research (in Chinese), 25(2): 108-114.
Lu L Y, He Z Q, Ding Z F, et al. 2014. Azimuth anisotropy and velocity heterogeneity of Yunnan area based on seismic ambient noise. Chinese J. Geophys. (in Chinese), 57(3): 822-836.
Ma X Y. 1989. Lithospheric Dynamics Atlas of China. Beijing: China Cartographic Publishing House, 32-33.
Qian X D, Li B J, Qin J Z. 2002. Study on shear wave splitting for sequence of the aftershocks of Yao'an M_S6.5 Earthquake in Yunnan earthquake. Research in China (in Chinese), 18(2): 157-165.
Qian X D, Qin J Z, Liu L F. 2011. Study on recent tectonic stress field in Yunnan region. Seismology and Geology (in Chinese), 33(1): 91-106.
Shi Y T, Gao Y, Wu J, et al. 2006. Seismic anisotropy of the crust in Yunnan, China: Polarizations of fast shear-waves. Acta Seismologica Sinica (in Chinese), 28(6): 574-585.
Shi Y T, Gao Y, Zhao C P, et al. 2009. A study of seismic anisotropy of Wenchuan earthquake sequence. Chinese J. Geophys. (in Chinese), 50(2): 398-407.
Shi Y T, Gao Y, Su Y J, et al. 2012. Shear-wave splitting beneath Yunnan area of southwest China. Earthquake Science, 25(1): 25-34.
Sun C Q, Lei J S, Li C, et al. 2013. Crustal anisotropy beneath the Yunnan region and dynamic implications. Chinese J. Geophys. (in Chinese), 56(12): 4095-4105, doi: 10. 6038/cjg20131214.
Tai L X, Gao Y, Cao F J, et al. 2008. Shear-wave splitting before and after the 1999 Xiuyan earthquake in Liaoning, China. Acta Seismologica Sinica (in Chinese), 30(4): 340-354.
Tai L X, Gao Y, Ma G F, et al. 2011. Crustal anisotropy in north Taiwan from shear-wave splitting. Chinese J.Geophys.(in Chinese), 54(9): 2233-2242, doi: 10.3969/j.issn.0001-5733.2011.09.005.
Wang X L, Liu J, Zhang G M, et al. 2006. Study on shear-wave splitting in the aftershock region of the Yao'an earthquake in 2000. Acta Seismologica Sinica (in Chinese), 28(2): 119-131.
Wu C D, Qin J D, Huang F G. 2004. Shear wave splitting of aftershocks of M_s6.0 Yongsheng Earthquake. Journal of Seismological Research (in Chinese), 27(2): 140-145.
Wu J P, Ming Y H, Wang C Y. 2004. Source mechanism of small-to-moderate earthquakes and tectonic stress field in Yunnan province. Acta Seismologica Sinica (in Chinese), 26(5): 457-465.
Yang G H, Wang Q, Wang M, et al. 2003. Current horizontal crustal movement and deformation characteristics in Yunnan area. Journal of Geodesy and Geodynamics (in Chinese), 23(2): 7-14.
Zha X H, Lei J S. 2013. Crustal thickness and Poisson's ratio beneath the Yunnan region. Science China Earth Sciences, 56(4): 693-702, doi: 10.1007/s11430-013-4583-8.