FAST TRACK PAPER: Seismic tomography of crustal P and S across Eurasia
FAST TRACK PAPER: Seismic tomography of crustal P and S across Eurasia
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DOI：
10.1111/j.1365-246x.2009.04109.x
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发表时间：
2009-04
影响因子：
2.8
通讯作者：
L. Steck;W. Phillips;K. Mackey;M. Begnaud;R. Stead;C. Rowe
中科院分区：
文献类型：
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作者：
L. Steck;W. Phillips;K. Mackey;M. Begnaud;R. Stead;C. Rowe
摘要 在本文中，我们提出了欧亚大陆区域 Pg 和 Sg 相位的反演结果，以探索其在了解上地壳速度结构方面的用途。从首先到达的压缩波和剪切波对速度结构的走时进行层析反演已在从实验室台式到整个地球的所有长度尺度上取得了巨大成功，而后来到达的相位的反演则受到更多限制。我们的反演是使用阻尼、平滑的 LSQR 实现来执行的，该实现可以求解站点和事件项以及沿着源和接收器之间的大圆路径的速度。结果与已发表的欧亚大陆上地壳速度大体一致，其中克拉通地区的速度主要较高。一般来说，但并非总是如此，在造山带和伸展区域以及深层沉积盆地中观察到较低的速度。来自当地和区域研究的 VP/VS 的现场比较与我们分辨率较高的研究中观察到的 Pg 与 Sg 速度的比率进行了很好的比较。分辨率是通过使用棋盘测试来确定的，这表明在数据密度较高的区域，我们可以将特征分辨率降低到至少 2°，在更广泛的区域上可能达到 4°。 Sg 的均方根残余减少量约为 25%，Pg 的残余减少量约为 30%。
SUMMARY In this paper, we present inversion results for regional Pg and Sg phases for the Eurasian continent to explore its use for understanding upper crustal velocity structure. Tomographic inversion of traveltimes from first arriving compressional and shear waves for velocity structure has been applied with great success at all length scales, ranging from the laboratory benchtop to the entire Earth, while inversion of later arriving phases has been much more limited. Our inversion is performed using a damped, smoothed LSQR implementation that solves for site and event terms as well as for velocity along great circle paths between the source and receiver. Results are broadly consistent with published upper crustal velocities for Eurasia, with predominantly high velocities in cratonic regions. Generally, but not always, lower velocities are observed in orogenic and extensional areas and in deep sedimentary basins. A spotcomparison of VP/VS from local and regional studies compares well with the ratio of observed Pg to Sg velocities from our study where resolution is high. Resolution is determined through the use of checkerboard tests, and these suggest that in regions where data density is high we can resolve features down to at least 2 ◦ , with 4 ◦ possible over broader areas. rms residual reductions are on the order of 25 per cent for Sg and 30 per cent for Pg.