利用介质的不均匀分布构建各向异性模型  

Constructing Anisotropic Model from Directional Heterogeneity Distribution

作　　者：石玉涛[1] 刘澜波 高原[1] 

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]Department of Civil and Environmental Engineering,University of Conneetieut,CT 06269,USA

出　　处：《地震》2015年第2期1-10,共10页Earthquake

基　　金：国家自然科学基金(41174042)

摘　　要：在复杂区域应力场的作用下,大范围扩容各向异性(extensive-dilatancy anisotropy,EDA)造成的裂隙定向排列形成了地壳内部介质的不均匀性。因此,地壳介质各向异性的描述不仅限于横向各向同性(transversely isotropic,TI)的理论。我们首先利用自相关函数随机扰动得到水平向小尺度速度不均匀,然后利用这种不均匀性描述地壳介质中EDA裂隙定向排列所造成的介质各向异性,利用数值模拟弹性波在该介质中的传播过程验证了利用介质的不均匀性构建介质的各向异性是一个有效、可靠的方法。可以将此方法应用到复杂地壳介质结构中,了解地震波在复杂地壳各向异性介质中的传播特征。Under the effect of complicated local stress, the aligned micro-cracks from extensive-dilatancy anisotropy （EDA） are the main anisotropic mechanism in the upper crust. Therefore, the seismic anisotropy study is not only based on transversely isotropic （TI） medium. In this study, the EDA micro-cracks are regarded as the directional ar rangement of molecular scale heterogeneity and be described by heterogeneous medium exercising an appropriate smooth disturbances autocorrelation function. According to the simulation of seismic waves by pseudospectral time-domain （PSTD） method in this equivalent anisotropic model, the directional heterogeneity is an effective and reliable method to describe anisotropy essentially, and can be extensively used in geological structure re- search and analysis of the characteristics of seismic wave propagation.

关 键 词：不均匀性 各向异性 伪谱法 数值模拟 

分 类 号：P315.7[天文地球—地震学]