Automated multimode phase speed measurements for high-resolution regional-scale tomography: application to North America
Automated multimode phase speed measurements for high-resolution regional-scale tomography: application to North America
复制标题
用于高分辨率区域尺度断层扫描的自动多模相位速度测量：在北美的应用
DOI：
10.1111/j.1365-246x.2010.04814.x
复制
发表时间：
2010
影响因子：
2.8
通讯作者：
G. Ekström
中科院分区：
文献类型：
--
作者：
K. Yoshizawa;G. Ekström
发展了一种从单一地震记录获得多模式相速度测量的全自动方法，并将其应用于北美三分量长周期地震记录的大数据集，构建了大陆尺度的高分辨率相速度图。我们的相速度估计方法是基于Yoshizawa和Kennett使用全局搜索方法(邻域算法)进行的完全非线性波形反演。整个波形拟合和估计相速度的评估过程已经完全自动化，采用了几个经验的定量措施，评估了波形拟合的质量和每个模式在选定的时间窗口中的相对贡献。测量的相速数据经过自动筛选以进行质量控制，包括对其可靠性的阈值评估以及异常值的检测和去除。这一新的自动化方法已被应用于北美台站记录的大型数据集，包括美国阵列公司最新的可移动台站。利用过去8年中记录的长周期三分量地震记录，我们成功地反演了大量的区域面波路径，其中包括20000多条基模瑞利波路径和10000多条高阶瑞利波路径以及基模乐夫波路径。区域距离的consistentresultsoftheautomatedmeasurementproceduresuggestthatthemethodworkswell，使我们能够对北美地区的多模式相速度进行高分辨率测绘。自动波形分析的结果还表明，单一地震记录的高模相速测量存在一些固有的局限性，特别是在短周期范围内，主要是由于高模到达的重叠以及振型分支之间的耦合。尽管在高模色散测量中存在这样的固有困难，但自动化方法使我们能够构建可靠的多模相速度图。目前的射线路径数据集严重偏向北美西半部，导致整个大陆的水平分辨率不统一。这个问题将通过美国阵列空间站未来的迁移来解决，以覆盖美国中部和东部。这种新的自动化方法可以成为高分辨率绘制区域三维横波结构(包括可能的各向异性)的有用工具。
SUMMARY A fully automated method for obtaining multimode phase speed measurements from a single seismogram has been developed and applied to a large data set of three-component longperiod seismograms in North America, constructing high-resolution phase speed maps on a continental scale. The method of our phase speed estimation is based on a fully non-linear waveform inversion by Yoshizawa & Kennett working with a global search method (the Neighbourhood Algorithm). The entire process of waveform fitting and the evaluation of the estimated phase speed have been fully automated employing several empirical quantitative measures, assessing the quality of waveform fit and the relative contributions of each mode in a chosen time window. The measured phase speed data undergo automatic screening for quality control, comprising the threshold evaluation of their reliability and outlier detection and removal. This new automated method has been applied to a large data set recorded at North American stations, including the latest transportable stations of USArray. Using long-period three-component seismograms recorded during the past eight years, we have successfully retrieved large numbers of regional surface wave paths, including over 20000 paths for the fundamental-mode Rayleigh waves over a wide range of frequencies, and over 10000 paths for the higher mode Rayleigh as well as the fundamental-mode Love waves. The consistentresultsoftheautomatedmeasurementproceduresuggestthatthemethodworkswell at regional distances, allowing us to perform a high-resolution mapping of multimode phase speeds in North America. The results of the automated waveform analysis also indicate some intrinsic limitations in the higher mode phase speed measurements from a single seismogram particularly in the short period range, mainly due to the overlapping of higher mode arrivals as well as coupling between mode branches. Despite such an innate difficulty in the higher mode dispersion measurements, the automated method allows us to construct reliable multimode phase speed maps. The current data set of ray paths is significantly biased towards the western half of North America, resulting in non-uniform horizontal resolution across the continent. This issue will be resolved by the future migration of the USArray stations to cover the central and eastern United States. The new automated method can be a useful tool for high-resolution mapping of regional 3-D shear wave structure including possible anisotropy.
影响因子：
2.8
作者：
N. Takeuchi
通讯作者：
N. Takeuchi
H.264编码器DCT的硬件实现及其评估
DOI：
--
发表时间：
2009
期刊：
影响因子：
--
作者：
Choong Geun Lee;V. G. Moshnyaga and K. Hashimoto;宮田康治
通讯作者：
宮田康治