地壳分层各向异性介质接收函数及其粒子群反演

Stratified crustal anisotropy from receiver function and its particle swarm inversion

地壳不同深度介质的地震各向异性是研究地壳不同深度范围变形方式的重要依据.鉴于地壳介质的复杂性,如何从远震体波接收函数中提取不同深度的各向异性参数仍是一个有待深入研究的课题.在已有研究的基础上,本文利用广义反射-透射系数矩阵方法计算的合成地震图,研究了复杂地壳分层各向异性介质的接收函数随反方位角(back azimuth)变化及不同层位各向异性参数对接收函数波场的影响,为各向异性介质接收函数的解释提供了新的理论依据.通过引入粒子群优化理论,发展了分层各向异性介质接收函数全局反演算法.数值及观测数据的验证结果表明,在各向同性速度模型确定的前提下,我们的方法能够可靠地提取地壳分层各向异性参数;在反演中引入曲波变换去噪技术,对于正确解析不同层位的各向异性参数具有重要价值.

The crustal anisotropy at multiple depths is essential for studying the vertical variation of the crustal deformation.Due to the complexity of the crust,the extraction of the crustal anisotropic parameters at different depths from teleseismic receiver function（RF）is an ongoing subject that requires further studies.Based on the previous works,this paper goes further to discuss the RF wavefield patterns of the stratified crustal anisotropy in terms of the generalized reflection and transmission coefficients method,which provides us a new theoretical basis for understanding the RF data with stratified anisotropic crustal models.In addition,we develop a global inversion method for extracting the stratified anisotropic model from RF via the particle swarm algorithm.The test results from both numerical and real data show that our method can correctly recover the anisotropic parameters of the multi-layered crustal model and distinguish the different anisotropic layers at each depth of the crust,as long as the isotropic velocity model is well determined.Noise suppression in RFs via the curvelet transform is valuable for the correct analysis of the crustal anisotropy at multiple depths.