Shear-wave splitting in the crust:Regional compressive stress from polarizations of fast shear-waves  

作　　者：Yuan Gao Yutao Shi Jing Wu Lingxue Tai 

机构地区：[1]Institute of Earthquake Science,China Earthquake Administration,Beijing 100036,China [2]Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Earthquake Science》2012年第1期35-45,共11页地震学报（英文版）

基　　金：supported by International Science and Technology Cooperation Program of China(2010DFB20190);National Natural Science Foundation of China(41040034 and 41174042);the support by basic research project of Institute of Earthquake Science,China Earthquake Administration(2009IES0211)

摘　　要：When propagating through anisotropic rocks in the crust, shear-waves split into faster and slower components with almost orthogonal polarizations. For nearly vertical propagation the polarization of fast shear- wave （PFS） is parallel to both the strike of the cracks and the direction of maximum horizontal stress, therefore it is possible to use PFS to study stress in the crust. This study discusses several examples in which PFS is applied to deduce the compressive stress in North China, Longmenshan fault zone of east edge of Tibetan plateau and Yunnan zone of southeast edge of Tibetan plateau, also discusses temporal variations of PFS orientations of 1999 Xiuyan earthquake sequences of northeastern China. The results are consistent to those of other independent traditional stress measurements. There is a bridge between crustal PFS and the crustal principal compressive stress although there are many unclear disturbance sources. This study suggests the PFS results could be used to deduce regional and in situ principal compressive stress in the crust only if there are enough seismic stations and enough data. At least, PFS is a useful choice in the zone where there are a large number of dense seismic stations.When propagating through anisotropic rocks in the crust, shear-waves split into faster and slower components with almost orthogonal polarizations. For nearly vertical propagation the polarization of fast shear- wave （PFS） is parallel to both the strike of the cracks and the direction of maximum horizontal stress, therefore it is possible to use PFS to study stress in the crust. This study discusses several examples in which PFS is applied to deduce the compressive stress in North China, Longmenshan fault zone of east edge of Tibetan plateau and Yunnan zone of southeast edge of Tibetan plateau, also discusses temporal variations of PFS orientations of 1999 Xiuyan earthquake sequences of northeastern China. The results are consistent to those of other independent traditional stress measurements. There is a bridge between crustal PFS and the crustal principal compressive stress although there are many unclear disturbance sources. This study suggests the PFS results could be used to deduce regional and in situ principal compressive stress in the crust only if there are enough seismic stations and enough data. At least, PFS is a useful choice in the zone where there are a large number of dense seismic stations.

关 键 词：polarization of fast shear-wave shear-wave splitting compressive stress in the crust seismic anisotropy 

分 类 号：P315.31[天文地球—地震学]