Bounds on Anisotropic Velocity Heterogeneity from Surface Waves and Body Phases

我们要求研究太平洋下上地幔的横向非均质性和各向异性，使用一种直接反演地球结构的三分量基波和高模面波和体相波形的技术。我们将集中在西太平洋、北太平洋和西北太平洋海盆开展前期工作，积累GDSN和WWSSN网络的数据。我们对横穿该地区的波形的初步观测表明，上地幔各向异性和不均一性是简单的年龄相关模型难以解释的，包括夏威夷西北部隆起和沙茨基隆起下方的大片异常快速速度。对“正常”路径极化各向异性的初步估计表明，SH速度到处都比SV速度快，至少在低速区底部是这样。用合成数据进行的实验表明，我们的技术能够解决各向异性随深度的分布和LID/各向异性之间的权衡。

We request for studies of the lateral heterogeneity and anisotropy of the upper-mantle beneath the Pacific Ocean, using a technique which inverts three-component fundamental and higher-mode surface-wave and body-phase waveforms directly for earth structure. We will concentrate our initial work on the western, northern, and northwestern Pacific Ocean basin, accumulating data from the GDSN and WWSSN networks. Our initial observations of waveforms traversing this region show substantial evidence for upper-mantle anisotropy and heterogeneity not easily explained by simple age-dependent models, including a large area of anomalous fast velocities beneath the northwestern Hawaiian Swell and the Shatsky Rise. Preliminary estimates of polarization anisotropy for "normal" paths indicate that SH velocities are everywhere faster than SV velocities at least to the bottom of the low-velocity zone. Experiments with synthetic data demonstrate the ability of our technique to resolve the distribution of anisotropy with depth and the lid/anisotropy tradeoff.