| 上地幔各向异性分析中地壳的影响 |
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| 引用本文： | 阮爱国,王椿镛,李清河,臧宏.上地幔各向异性分析中地壳的影响[J].地球物理学报,2004,47(3):441-448. |
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| 作者姓名： | 阮爱国 王椿镛 李清河 臧宏 |
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| 作者单位： | 1.国家海洋局第二海洋研究所和海底科学重点实验室，杭州 310012 2 中国地震局地质研究所博士后流动站，北京 100029 3 中国地震局地球物理研究所，北京 100081 4 江苏省地震局，南京 210014 |
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| 基金项目： | 国家重点基础研究发展规划项目 (95 - 1 3 - 0 2 - 0 3)，国家自然科学基金项目 (40 0 740 1 0 ) |
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| 摘 要： | 应用伪谱法研究了地壳各向异性对上地幔各向异性分析的影响. 用几种不同情况下的两层各向异性模型，模拟了全波场，着重分析了不同深度观测点上的剪切波分裂特征. 结果表明，当地壳为各向同性或其各向异性主轴与上地幔重合或相互垂直时，在地壳观测到的快、慢剪切波的偏振方向保持了上地幔中的偏振方向；重合时，快、慢波走时延迟增大；垂直时，走时延迟减小. 当地壳的各向异性主轴与上地幔成一般夹角时，其粒子运动轨迹变得十分复杂，不能直观地识别上地幔各向异性中的快波方向，对走时延迟也有一定的影响. 将常用的两种分析方法应用于对模拟结果的反演，发现当地壳各向异性与上地幔各向异性方向为一般夹角时，反演结果会出现较大的误差或误判. 进而提出解决这一问题的方法，一是综合多种方法的结果；二是由拟合残差或相关系数等值线作进一步的确定.
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| 关 键 词： | 地壳影响 上地幔各向异性 伪谱法 数值模拟 |
| 文章编号： | 0001-5733(2004)03-0441-08 |
| 收稿时间： | 2003-5-17 |
| 修稿时间： | 2003-12-16 |
Effect of the crust on the analysis of the upper mantle anisotropy |
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| RUAN Ai Guo , WANG Chun Yong LI Qing He ZANG Hong Second Institute of Oceanography & Key Lab of Submarine Geosciences,State Oceanic Administration,Hangzhou ,China Post Doctor Work Station of Institute of Geology,China Seismological Bureau,Beijing ,China Institute of Geophysics,China Seismological Bureau,Beijing ,China Seismological Bureau of Jiangsu Province,Nanjing ,China.Effect of the crust on the analysis of the upper mantle anisotropy[J].Chinese Journal of Geophysics,2004,47(3):441-448. |
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| Authors: | RUAN Ai Guo WANG Chun Yong LI Qing He ZANG Hong Second Institute of Oceanography & Key Lab of Submarine Geosciences State Oceanic Administration Hangzhou China Post Doctor Work Station of Institute of Geology China Seismological Bureau Beijing China Institute of Geophysics China Seismological Bureau Beijing China Seismological Bureau of Jiangsu Province Nanjing China |
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| Institution: | 1.Second Institute of Oceanography & Key Lab of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China 2 Post Doctor Work Station of Institute of Geology, China Seismological Bureau, Beijing 100029, China 3 Institute of Geophysics, China Seismological Bureau, Beijing 100081, China 4 Seismological Bureau of Jiangsu Province, Nanjing 210014, China |
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| Abstract: | The pseudo spectrum method is used to simulate the crust effect on the analysis of the upper mantle anisotropy. A model of two layer anisotropy media is used to simulate the crust and the upper mantle respectively, and elastic wave fields are calculated in four coupling conditions between the two layers. The characteristics of split shear waves at various depths are analyzed in detail. The results show when the crust is isotropic or its anisotropic orientations are parallel to or perpendicular to that of the upper mantle, the fast or slow directions observed in the crust keep the same as that in the upper mantle. The time delay increases when they are parallel to each other or decreases when they are perpendicular to each other. But in other conditions the motion of particles in the crust becomes complicated and the fast direction of the upper mantle is difficult to be directly picked out and the time delay is also changed due to the effect of the crust anisotropy. Furthermore, two popular approaches are used to inverse the anisotropy parameters from simulated results. It is found that when the angle between the anisotropy orientations of the crust and the upper mantle is neither parallel nor perpendicular, the inversed fast direction of the upper mantle maybe is incorrect. It is suggested that in such case one can use several different inversion techniques together and refer to the contours of residual or cross correlation for further determination of anisotropy parameters of the upper mantle. |
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| Keywords: | Effect of crust Upper mantle anisotropy Pseudo-spectrum Numerical simulation |
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