六方各向异性介质方位矢量波动方程及其相速度

Azimuth vector wave equation and its phase velocity in hexagonal anisotropy medium

长春地质学院, 长春130026

Changchun Coliege of Geology, Changchun City, Interna Postcode 130026

地壳中普遍存在的六方各向导性介质是人们重点研究的对象。本文的主要工作是, 通过坐标旋转方法得到了六方各向异性介质的方位矢量波动方程。用此方程可以直接求取介质的相速度, 这是求取相速度一种非常简便的方法。用这种方法求取了TIM(横向各向同性)和EDA(裂隙各向异性)介质的相速度, 强调指出横波双折射第二消失区存在的部位和要满足的条件, 并指出横波双折射消失区和零延迟时在空间和时间上是统一的。这些工作有利于各向异性介质正演数值模拟和相应反演工作的开展, 对实际观测中震源和接收方式的设计有一定指导作用。

The hexagonal anisotropy medium commonly existing inside the crust has been a focal point of research to geophysicists. Involed in the paper is an azimuth vector wave equation resulting from coordinate rotation for hexagonal anisotropy medium, with which phase velocities can be easily derived. As an applied cxample, we have used the equation to obtain the phase velocities in both TIM and EDA media and figured out the second consuming zone of a shear wave birefringence and the conditions required to be sat isfied for t he second consuming zone to exist. It turns out that t his zone is coincidcnt with thc zero-lag time in both space and time. These works are definitely helpful to forward numerical modelling and corresponding inversion for anisotropy media and can serve to a certain extent as a guide in designing shooting and receiving patterns in a practical survey.