基于横波分裂的青藏高原多圈层各向异性研究进展

有关青藏高原横波分裂的各向异性研究已经开展了近30年,在理论方法和实际应用方面取得了重要进展,并获取了大量的横波分裂测量结果,为认识青藏高原壳幔各向异性变形特征和动力学机制提供了重要的依据.本文首先介绍了地震各向异性的来源与应用,随后回顾了横波分裂分析方法的发展,简述了各种横波分裂方法的原理,最后通过总结近30年来青藏高原上地壳、整个地壳和上地幔横波分裂各向异性研究成果,系统分析了青藏高原壳幔各向异性变形特征.基于各横波分裂结果的对比分析来看,XKS波分裂测量结果最为稳定,近震直达S波分裂测量结果次之,而Pms波分裂测量结果相对离散,往往相同区域内不同的研究结果差异较大,主要原因可能是相比XKS波和近震直达S波,Pms波的信噪比较低,次要原因可能是各研究在方法和处理分析等方面的差异.

Reviews on seismic anisotropy based on shear-wave splitting in the Tibetan Plateau

The research on the anisotropy of shear wave splitting in the Tibetan Plateau has been carried out for nearly 30 years,and important progress has been made in theoretical methods and practical applications.A large number of shear wave splitting results obtained from teleseismic records,which provides an important basis for understanding the deformation characteristics and dynamic mechanism of the crust and mantle anisotropy in the Tibetan Plateau.In this paper,we first introduce the source and application of seismic anisotropy in the Earth's interior;then review the development of shear wave splitting analysis methods,briefly expounds the principle of various shear wave splitting methods;finally,systematically analyze the crust-mantle anisotropic characteristics in the Tibetan Plateau by summarizing the shear wave splitting results of the anisotropy in the upper crust,crust and upper mantle in the Tibetan Plateau over the past 30 years.Based on the comparison of the shear wave splitting results,we find the XKS wave splitting results are the most stable,the direct S wave splitting results from local earthquakes are better,but the Pms wave splitting results are more discrete.The Pms wave splitting results of different studies in the same research area are often different.The main reason may be the signal-to-noise ratio of the Pms wave is lower than that of the XKS wave and the direct S wave of the local earthquake.The secondary reason may be the differences in methods and processing analysis of various studies.