Refraction Modeling with Lateral Heterogeneity

当垂直方向为埋入方向时，用于横向变化地球模型的反射率算法速度太慢，不能用于实际的折射数据建模。然而，当采用水平方向时，嵌入方向的计算量(至多)随源-接收器偏移量线性增加。一般来说，水平传播子有连续谱和点谱。点谱很大，很难在体波频率上定位，但连续谱的位置总是已知的。通过在模型中加入低速下半空间，以牺牲点谱为代价，放大了连续谱。我们建议通过将相邻垂直切片的连续谱耦合在一起来处理横向非均质性。

The reflectivity algorithm for laterally varying earth models is too slow to be practical for modeling refraction data when the vertical direction is the imbedding direction. However when the horizontal direction is made the direction of imbedding the cost of computation increase (at most) linearly with source-receiver offset. In general the horizontal propagator has a continuous spectrum and a point spectrum. The point spectrum is large and troublesome to locate at body-wave frequencies but the location of the continuous spectrum is always known. By adding a low-velocity lower half space to the model the continuous spectrum is enlarged at the expense of the point spectrum. We propose to treat lateral heterogeneity by coupling together the continuous spectra of adjacent vertical slices.