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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Stochastic analysis of shear-wave splitting length scales
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Stochastic analysis of shear-wave splitting length scales

机译：剪切波分裂长度尺度的随机分析

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The coherence of azimuthal seismic anisotropy, as inferred from shear-wave splitting measurements, decreases with the relative distance between stations. Stochastic models of a two-dimensional vector field defined by a von Karma'n [T. von Karma'n, Progress in the statistical theory of turbulence, J. Mar. Res., 7 (1948) 252-264.] autocorrelation function with horizontal correlation length L provide a useful means to evaluate this heterogeneity and coherence lengths. We use the compilation of SKS splitting measurements by Fouch [M. Fouch, Upper mantle anisotropy database, accessed in 06/2006, http:H geophysics.asu.edu/anisotropy/upper/] and supplement it with additional studies, including automated measurements by Evans et al. [Evans, M.S., Kendall, J.-M., Willemann, R.J., 2006. Automated SKS splitting and upper-mantle anisotropy beneath Canadian seismic stations, Geophys. J. Int. 165, 931-942, Evans, M.S., Kendall, J.-M., Willemann, R.J. Automated splitting project database, Online at http://www.isc.ac.uk/SKS/, accessed 02/2006]. The correlation lengths of this dataset depend on the geologic setting in the continental regions: in young Phanerozoic orogens and magmatic zones L similar to 600 km, smaller than the smooth L similar to 1600 km patterns in tectonically more stable regions such as Phanerozoic platforms. Our interpretation is that the relatively large coherence underneath older crust reflects large-scale tectonic processes (e.g. continent-continent collisions) that are frozen into the tectosphere. In younger continental regions, smaller scale flow (e.g. slab anomaly induced) may predominantly affect anisotropy. In this view, remnant anisotropy is dominant in the old continents and deformation- induced anisotropy caused by recent asthenospheric flow is dominant in active continental regions and underneath oceanic plates. Auxiliary analysis of surface-wave anisotropy and combined mantle flow and anisotropic texture modeling is consistent with this suggestion. In continental regions, the further exploration of a stochastic description of seismic anisotropy may form a useful counterpart to deterministic for-ward modeling, particularly if we wish to. understand the origin of discrepancies in heterogeneity estimates based on different seismological data sets. (c) 2007 Elsevier B.V. All rights reserved.
机译：从剪切波分裂测量推断出，方位地震各向异性的相干性随着站之间的相对距离而减小。由von Karma'n定义的二维向量场的随机模型[T. von Karma'n，《湍流统计理论的进展》，J。Mar. Res。，7（1948）252-264。]具有水平相关长度L的自相关函数提供了一种有用的方法来评估这种异质性和相干长度。我们使用Fouch [M. Fouch，上地幔各向异性数据库，2006年6月访问，http：// H geophysics.asu.edu/anisotropy/upper/]，并通过其他研究加以补充，包括Evans等人的自动测量。 [Evans，M.S.，Kendall，J.-M.，Willemann，R.J.，2006年。加拿大地震台站Geophys下的自动SKS分裂和上地幔各向异性。 J.国际165，931-942，M.S。Evans，J.-M。Kendall，R.J。Willemann。自动化拆分项目数据库，在线，网址为http://www.isc.ac.uk/SKS/，访问时间：02/2006]。该数据集的相关长度取决于大陆地区的地质背景：在新生代造山带和岩浆带中，L类似于600 km，在构造上较稳定的区域（如Phanerozoic平台）中小于L类似于1600 km模式。我们的解释是，旧地壳下方相对较大的连贯性反映了被冻结到构造层中的大规模构造过程（例如大陆与大陆的碰撞）。在较年轻的大陆地区，较小尺度的水流（例如，引起平板异常）可能主要影响各向异性。按照这种观点，在旧大陆，残余各向异性是主要的，而在活跃的大陆区域和大洋板块下面，由新近的软流圈流动引起的由变形引起的各向异性是主要的。辅助分析面波各向异性以及组合的地幔流和各向异性纹理模型与该建议是一致的。在大陆地区，对地震各向异性的随机描述的进一步探索可能会与确定性正演模拟形成有用的对应关系，尤其是在我们愿意的情况下。了解基于不同地震数据集的非均质性估计中差异的起源。 （c）2007 Elsevier B.V.保留所有权利。

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