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首都圈西北部地区地壳介质地震各向异性特征初步研究
引用本文:吴晶,高原,陈运泰,黄金莉.首都圈西北部地区地壳介质地震各向异性特征初步研究[J].地球物理学报,2007,50(1):209-220.
作者姓名:吴晶  高原  陈运泰  黄金莉
作者单位:1.中国地震局地震预测研究所,北京100036 2 中国地震局地球物理研究所,北京100081
基金项目:国家自然科学基金,国家发展和改革委员会资助项目
摘    要:本研究使用首都圈数字地震台网2002年01月~2003年12月的波形记录资料,采用SAM方法,进行了剪切波分裂的分析,得到首都圈西北部地区地壳介质地震各向异性的初步结果.根据对有3条以上可靠记录的14个台站的统计分析,得到首都圈西北部地区的剪切波分裂的统计平均结果为: 快剪切波平均偏振方向为NE699°±445°,慢剪切波平均时间延迟为444±293(ms/km).研究认为,NE699°±445°的快剪切波平均偏振方向暗示了该区域的水平主压应力方向,快剪切波偏振方向的第一优势取向揭示了NWW近E W方向的原地水平主压应力的构造意义,凸现了NWW向的张家口—蓬莱断陷带.通过快剪切波偏振方向,本研究进一步证实,位于活动断裂上的台站的快剪切波偏振方向的优势取向与断裂走向一致,认为南口—孙河断裂和夏垫断裂是两个活动断裂,而八宝山断裂可能是个并不太活跃的活动断裂.华北盆地里的快剪切波偏振方向显示出复杂的分布特征,对应了盆地凹陷区里许多断裂互相交汇造成区域主压应力场受到局部调整的复杂图像.研究还认为慢剪切波时间延迟急剧的梯度变化可能与地壳深部的温度变化有关联.

关 键 词:首都圈  地震各向异性  剪切波分裂  快剪切波偏振方向  慢剪切波时间延迟  活动断裂  
文章编号:0001-5733(2007)01-0209-12
收稿时间:2006-3-9
修稿时间:2006-03-09

Seismic anisotropy in the crust in northwestern capital area of China
WU Jing,GAO Yuan,CHEN Yun-Tai,HUANG Jin-Li.Seismic anisotropy in the crust in northwestern capital area of China[J].Chinese Journal of Geophysics,2007,50(1):209-220.
Authors:WU Jing  GAO Yuan  CHEN Yun-Tai  HUANG Jin-Li
Institution:1.Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China 2 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
Abstract:Seismic anisotropy is obtained in the crust in northwestern capital area by shear wave splitting analysis, using the SAM technique. The seismic data was recorded by the Capital Area Seismic Network from Jan. 2002 to Dec. 2003 The results at 14 stations in all, every of which has at least 3 records available, are statistically discussed in this paper. The statistical results show that the average polarization of fast shear waves is at NE699°±445° and the time delay of slow shear waves is 444±293 (ms/km). The average polarization of fast shear waves of NE699°±445° suggests the direction of maximum horizontal principal compressive stress in this area. The most predominant polarization direction of fast shear wave suggests the tectonic implication of horizontal principal compressive stress at the direction NWW or nearly E_to_W, which expose the Zhangjiakou Penglai depression fault zones with strike NWW. According to the polarization of fast shear wave, this study verifies that the predominant polarizations of fast shear wave at stations on active faults are consistent with fault strike. Possibly, both the Nankou Sunhe fault and Xiadian fault are two active faults while the Babaoshan fault is possibly a less active fault. The polarizations of fast shear wave in the North China Basin show the complexity, consistent with the complicated pattern of regional principal compressive stress varying locally, induced by many faults crossing in the depression zone within the basin. This study also suggests that the quick change of time delays of slow shear waves is possibly related to the temperature change in deep crust.
Keywords:Capital area  Seismic anisotropy  Shear-wave splitting  Polarization of fast shear-wave  Time delay  Active fault
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