Seismic anisotropy in the crust in northeast margin of Tibetan Plateau and tectonic implication

doi:10.6038/cjg20151117

	Seismic anisotropy in the crust in northeast margin of Tibetan Plateau and tectonic implication
	Guo, GH; Zhang, Z; Cheng, JW; Dong, ZP; Yan, JP; Ma, YW; Guo, GH (reprint author), Key Lab Mech Disaster & Environm Western China, Lanzhou 730000, Peoples R China.
刊名	CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
	2015-11
卷号	58 期号:11 页码:4092-4105
关键词	Northeastern margin of Tibetan plateau Seismic anisotropy in the crust Shear-wave splitting Regional stress Local faulting
ISSN号	0001-5733
DOI	10.6038/cjg20151117
其他题名	青藏高原东北缘地壳各向异性的构造含义
文献子类	Article
英文摘要	The northeastern margin of Tibetan plateau is surrounded by the Alashan block to the north, the Tarim basin to the northwest, the Ordos block to the east, and Songpan-Garze terrane to the south. As the northern terminus of contiguous deformation, it records far field effects of collision and convergence occurring between the Indian and Eurasian, it is still in the stages of uplift and deformation, so it is an ideal region for studying the far field effects of collision and convergence between the India and Eurasian plate. Seismic anisotropy is one of the main specialities of the Earth, which can be interpreted with the Lattice Preferred Orientation (LPO) of minerals and shape Preferred Orientation of cracks or melts caused by tectonic stress. In this study, we use the seismic data recorded by the Gansu and Ningxia Province Seismic Network from Jan. 2001 to Oct. 2010. And seismic anisotropy is obtained by using the SAM technique. The average time delay and polarization are caused by the regional structure and stress field, whereas the residual values of the splitting parameters are considered to be related to local structures such as local faults. The residual polarization of fast shear-waves suggests the strike direction of local fault. The residual delay of slow shear-waves suggests the contribution extent induced by local fault. During our data process, we take the posterior choice on earthquakes with small epicenters that is a makeshift for the regions lacking earthquakes, but is useful to increase the credibility of the analysis for fast-wave polarization. The results show that the crustal seismic anisotropy in the northeastern margin of Tibetan vary in different tectonic blocks. There are the two average polarization of fast shear-waves, which are individually at NE47. 72 degrees +/- 21.83 degrees and 121.65 degrees +/- 22.07 degrees, and the average time delay of slow shear-waves is 2.63 +/- 1.03 ms . km(-1). The first dominant polarization of fast shear-waves is almost consistent with the regional principal compressive stress due to collision between Indian and Asian plate. The second predominant polarization direction of fast shear-waves is in the NWW direction which indicates the influence by the deep fault. The delay time of slow shearwaves increases from southweastern to north eastern in the study area. The residual polarization of fast shear-waves are almost consistent with the strike of local fault, and the residual delay indicates the contribution extent induced by the local faults that means which part has a higher effect. Compared with the upper mantle anisotropy results, crust-mantle anisotropy are different in Qilian-Hexi Corrider, while they have some consistence in the southeast of Gansu.
学科主题	Geochemistry & Geophysics
出版地	BEIJING
资助项目	国家自然科学基金项目 ; 中央高校基本科研业务费专项资金
项目编号	国家自然科学基金 ; 兰州大学中央高校基本科研业务费专项资金
语种	中文
CSCD记录号	CSCD:5579395
WOS记录号	WOS:000365695200017
资助机构	NSFC ; LZU
内容类型	期刊论文
源URL	[http://ir.lzu.edu.cn/handle/262010/178491]
专题	土木工程与力学学院_期刊论文
通讯作者	Guo, GH (reprint author), Key Lab Mech Disaster & Environm Western China, Lanzhou 730000, Peoples R China.
推荐引用方式 GB/T 7714	Guo, GH,Zhang, Z,Cheng, JW,et al. Seismic anisotropy in the crust in northeast margin of Tibetan Plateau and tectonic implication[J]. CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,2015,58(11):4092-4105.
APA	Guo, GH.,Zhang, Z.,Cheng, JW.,Dong, ZP.,Yan, JP.,...&Guo, GH .(2015).Seismic anisotropy in the crust in northeast margin of Tibetan Plateau and tectonic implication.CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION,58(11),4092-4105.
MLA	Guo, GH,et al."Seismic anisotropy in the crust in northeast margin of Tibetan Plateau and tectonic implication".CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION 58.11(2015):4092-4105.