Anisotropic Layering and Seismic Body Waves: Deformation Gradients, Initial S-Polarizations, and Converted-Wave Birefringence
Anisotropic Layering and Seismic Body Waves: Deformation Gradients, Initial S-Polarizations, and Converted-Wave Birefringence
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DOI：
10.1007/s00024-021-02755-6
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发表时间：
2021-05
影响因子：
2
通讯作者：
Xiaoran Chen;Jeffrey Park;V. Levin
中科院分区：
文献类型：
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作者：
Xiaoran Chen;Jeffrey Park;V. Levin
我们应用一种更新的计算机反射率合成地震记录算法来研究地震平面波在水平分层各向异性介质中传播的观测情景。基于商业软件包Matlab， ANIMATIVITY软件可以使用全弹性张量描述的各向异性模型或使用具有对称轴的弹性张量的通用符号来计算合成地震图。该算法使我们能够模拟具有高频分量的波传播，并在一步中考虑所有的透射和反射系数。我们用合成的P-S接收函数在层状各向异性介质中验证了ANIMATIVITY代码，并与传统的反射率代码进行了比较。对比各向异性急剧转变和渐变转变模型的合成rf，我们观察到渐变转变模型中的特征可能被误解为倾斜界面引起的。我们发现S-P接收函数有可能通过垂直分量上sp相位振幅的反向变化来约束深度的各向异性。我们得出结论，实际使用S接收函数来研究各向异性将取决于准确确定初始S波极化。剪切波分裂的动态模拟包括在分裂的SKS波之前的S-P转换波。
We apply an updated computer algorithm for reflectivity synthetic seismograms to examine observational scenarios for seismic plane-wave propagation through horizontally stratified anisotropic media. Based on the commercial software package Matlab, the ANIMATIVITY software can compute synthetic seismograms using anisotropic models described either by a full elastic tensor or using common notations for an elastic tensor with a symmetry axis. This algorithm enables us to simulate wave propagation with high frequency components and to consider all transmission and reflection coefficients in one step. We validate the ANIMATIVITY code with synthetic P–S receiver functions in layered anisotropic media, compared against legacy reflectivity codes. Contrasting synthetic RFs for models with either sharp or gradual anisotropy transitions, we observe features in the gradual-transition models that could be misconstrued as caused by dipping interfaces. We find that S–P receiver functions have the potential to constrain anisotropy at depth via the back-azimuth variation of Sp-phase amplitude on the vertical component. We conclude that practical use of S receiver functions to investigate anisotropy will depend on accurate determination of the initial S-wave polarization. The ANIMATIVITY simulations of shear-wave splitting include S–P converted waves that precede the split SKS wave.