利用莫霍面Ps震相研究中国东北地区地壳各向异性

摘要

利用中国东北地区布设的65套宽频带数字地震仪2009年6月-2011年6月记录的远震事件,用时间域最大熵谱反褶积方法提取接收函数,并用改进的剪切波分裂分析方法对该区地壳介质各向异性参数进行研究,获得了该区地壳介质各向异性图像.结果表明,该区地壳介质各向异性快波偏振方向大致为北西向,快慢波时间延迟在0.15-0.3s之间；但有7个台站下方地壳各向异性快波方向表现为北东向,可能与当地复杂构造有关.该区地壳各向异性快波偏振方向与主压应力场方向近乎垂直,与板块移动方向基本一致,与SKS/SKKS各向异性快波方向也基本一致.推断本研究区地壳介质各向异性反映了该区的主张应力方向,且主要各向异性来源于中下地壳,暗示了壳幔垂直变形的一致性.%Using teleseismic events recorded by 65 broad-band digital seismic stations during June 2009 to June 2011 in Northeast China,we calculated receiver functions by conducting maximum entropy deconvolution in time domain,and obtained the crustal anisotropy parameters by using the improved shearwave splitting analysis.The result shows that in Northeast China,the dominant direction of fast wave polarity is approximately in NW-SE in this region,and the time delay between the fast and slow waves is 0.15-0.3 seconds.But the fast wave polarity direction is in NE-SW beneath other 7 stations,possibly due to the effect of local complex structure.Through a comparison study we find that the polarization direction of the fast wave is nearly perpendicular to the direction of principal compressive stress,and is approximately the same as the direction of the Eurasian plate movement and the result of SKS/SKKS analysis.It can be concluded that our result has revealed the tensile stress and the anisotropy may come from the middle and lower part of the crust in this region.