摘要
地球椭球面上的经线交于极点而纬线则相互平行。地图上的经纬网是地球椭球面上的经纬网的拓扑映射。投影网中极点到坐标原点的距离函数关联着7类常规地图投影的分类。距离等于零时对应着方位投影;距离为有限由于精确传播特征表达式较复杂,不利于参数反演,因此有必要推导其近似的线性表达式,本文主要完成了三个方面的工作:用摄动法求解Christoffel方程,进一步用确定了qp、qs波的相速度、偏振向量;推导了极端弱各向异性介质中qP、qS波群速度的一阶表达式,并对已有的研究成果进行了补充和完善;在极端各向异性表达式的基础上,推导了VTI、HTI介质中的地震波属性表达式。
Due to the complexity of the exact propagation characteristic expression, it is not conducive to the parameter inversion, so it is necessary to derive its approximate linear expression. This paper mainly completes three aspects of the work: phase velocity and polarization vector of the wave are determined further by solving Christoffel equation using perturbation method;the first-order expressions of qp and qs wave group velocities in extremely weakly anisotropic media are deduced, and the existing research results are supplemented and improved;the expressions of seismic wave attributes in VTI and HTI media are deduced based on the expression of extreme anisotropy.
