We investigate effects of realistic Earth's lithospheric structures on measurements of SKS seismic waves birefringence, which could be perturbed by different factors. We present SKS measurements recorded in four different tectonic settings. For each case, a realistic lithospheric structure is assumed and synthetic SKS splitting measurements are compared with the field observations. Our results show that (a) in a simple case, where anisotropy is aligned in both the lithospheric mantle and the asthenosphere, the SKS measurements can be safely interpreted as dominantly related to asthenospheric mantle flow; (b) in case of multilayer anisotropy in the lithospheric mantle, SKS measurement can correspond to a combination of the different fast‐axis orientations and intensities of the anisotropic layers, dominated by the layer with stronger anisotropy; (c) across orogens, where highly anisotropic (≥10%) crustal sections are present, a relevant percent (30–40%) of SKS measurement can be explained by crustal contributions, with additional challenge related to the different direction of retrieved and expected symmetry axis; and finally, (d) in subduction zones, even in the absence of mantle corner flow, subducted crust materials can interplay with the overriding plate to generate an interpretable SKS observation. We conclude that complex crustal and/or lithospheric anisotropy can lead to erroneous SKS splitting parameters interpretations in terms of mantle deformations. We show in particular that complex crustal anisotropy can produce both important time delay and back azimuthal pattern. We also confirm that SKS splitting parameters do not allow to identify the presence of more than two anisotropic layers in the mantle.

中文翻译：

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真实地球情况下岩石圈和软流圈的各向异性建模：对SKS测量影响的关键评估

我们研究了现实的地球岩石圈结构对SKS地震波双折射测量的影响，这可能会受到不同因素的干扰。我们介绍了在四种不同构造环境中记录的SKS测量值。对于每种情况，均假设为现实的岩石圈结构，并将合成的SKS分裂测量结果与现场观测结果进行比较。我们的结果表明：（a）在岩石圈地幔和软流圈都各向异性排列的简单情况下，可以安全地将SKS测量值解释为与软流圈地幔流起主要关系；（b）在岩石圈地幔中存在多层各向异性的情况下，SKS测量可以对应于各向异性层的不同快轴方向和强度的组合，以各向异性较强的层为主；（c）在整个造山带中，存在着高度各向异性（≥10％）的地壳断面，可以用地壳贡献来解释相关百分比（30％至40％）的SKS测量值，另外的挑战与取回和预期的不同方向有关对称轴 最后，（d）在俯冲带中，即使没有地幔角流，俯冲的地壳物质也可以与上覆板相互作用，产生可解释的SKS观测结果。我们得出的结论是，复杂的地壳和/或岩石圈各向异性可能会导致地幔变形方面的SKS分裂参数解释错误。我们特别表明，复杂的地壳各向异性既可以产生重要的时间延迟，又可以产生反向方位角模式。