Monte-Carlo inversion for a global shear-velocity model of the crust and upper mantle
Monte-Carlo inversion for a global shear-velocity model of the crust and upper mantle
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DOI：
10.1046/j.1365-246x.2002.01742.x
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发表时间：
2002-10
影响因子：
2.8
通讯作者：
N. Shapiro;M. Ritzwoller
中科院分区：
文献类型：
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作者：
N. Shapiro;M. Ritzwoller
总结我们描述了一种方法来反演面波频散数据的剪切速度模型在地壳和上地幔的不确定性。反演是一个多步骤的过程，约束的先验信息，最终在马尔可夫链蒙特-卡罗采样的模型空间，以产生一个合奏的可接受的模型在每个空间节点。该模型是径向各向异性的最上层地幔的平均深度约为200公里，是各向同性的其他地方。该方法应用于一个2 × 2的网格上，对基模表面波群速度和相速度（瑞利群速度，16 - 200 s;洛夫群速度，16 - 150 s;瑞利和洛夫相速度，40 - 150 s）的大型数据集进行全局计算。集合的中间（中值模型）定义了估计的模型，模型走廊的半宽度提供了不确定性估计。通过不确定性估计，可以确定该模型的稳健特征，这些特征通常只持续到250公里的深度。我们将出现在可接受模型集合的每个成员中的特征称为“持久性”。持续的特征包括大洋岩石圈和软流圈随年龄变化的更清晰的图像，大陆根，上地幔的伸展构造特征，俯冲岩石圈的浅部，以及径向各向异性的分辨率提高。特别是，我们没有发现令人信服的证据，“负各向异性”（vsv >v sh）在世界岩石圈的任何地方。
SUMMARY We describe a method to invert surface wave dispersion data for a model of shear velocities with uncertainties in the crust and uppermost mantle. The inversion is a multistep process, constrained by a priori information, that culminates in a Markov-chain Monte-Carlo sampling of model space to yield an ensemble of acceptable models at each spatial node. The model is radially anisotropic in the uppermost mantle to an average depth of about 200 km and is isotropic elsewhere. The method is applied on a 2 ◦ × 2 ◦ grid globally to a large data set of fundamental mode surface wave group and phase velocities (Rayleigh group velocity, 16‐200 s; Love group velocity, 16‐150 s; Rayleigh and Love phase velocity, 40‐150 s). The middle of the ensemble (Median Model) defines the estimated model and the half-width of the corridor of models provides the uncertainty estimate. Uncertainty estimates allow the identification of the robust features of the model which, typically, persist only to depths of ∼250 km. We refer to the features that appear in every member of the ensemble of acceptable models as ‘persistent’. Persistent features include sharper images of the variation of oceanic lithosphere and asthenosphere with age, continental roots, extensional tectonic features in the upper mantle, the shallow parts of subducted lithosphere, and improved resolution of radial anisotropy. In particular, we find no compelling evidence for ‘negative anisotropy’ (vsv >v sh) anywhere in the world’s lithosphere.