Seismic Surface Waves and Crustal and Upper Mantle Structure (Paper 7R0967)
Seismic Surface Waves and Crustal and Upper Mantle Structure (Paper 7R0967)
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DOI：
10.1029/rg016i001p00001
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发表时间：
1978-02
期刊：
影响因子：
--
通讯作者：
R. Kovach
中科院分区：
文献类型：
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作者：
R. Kovach
地震面波数据已被用于推断各种传播路径上的地球结构的细节。测量面波频散的实验方法包括傅里叶相位法、时间相关法、带通滤波法、群延迟时间法和各种数字“移动窗口”技术。对于不同的构造区，如地盾、东亚大陆台地、裂谷、海洋和山脉，面波数据表现出不同的观测特征。用于从色散测量确定速度模型的反演过程利用试错过程或相速度和群速度相对于模型参数的偏导数的应用与线性反演理论相结合。观测到的面波资料强调，地壳和上地幔结构存在明显的横向变化，大陆和海洋本身也是不均匀的。屏蔽区具有最高值的剪切波速度与深度和一个相对较弱的地幔低速带。另一方面，裂谷区剪切速度低得多，低速带非常明显。在海洋之下，覆盖低速区的盖层厚度不一，随着海底年龄的增加而增厚。170-200公里以上的平均速度在海洋下比在大陆下小。海洋路径上传播的面波衰减比大陆路径，但详细的区域研究缺乏。
Seismic surface wave data have been used to infer details of earth structure over various propagation paths. Experimental methods for measuring surface wave dispersion include the Fourier phase method, the time correlation method, the band-pass filtering method, the group delay time method, and various digital ‘moving window’ techniques. Surface wave data exhibit distinctive observational characteristics for different tectonic provinces such as shields, aseismic continental platforms, rifts, oceans, and mountains. Inversion procedures used to determine velocity models from dispersion measurements utilize trial and error procedures or application of partial derivatives of phase and group velocity with respect to model parameters combined with linear inverse theory. The observed surface wave data emphasize that there are pronounced lateral variations in crustal and upper mantle structure and the continents and oceans are themselves inhomogeneous. Shield areas possess the highest values of shear wave velocities with depth and a relatively weak mantle low-velocity zone. On the other hand, rift areas have much lower shear velocities and a very pronounced low-velocity zone. Under the oceans the lid overlying the low-velocity zone is variable in thickness and thickens with the increasing age of the ocean floor. The average velocity above 170–200 km is less under oceans than under continents. Surface waves propagating over oceanic paths are attenuated more than continental paths, but detailed regional studies are lacking.