Nearly Normal PS Reflections Using First Order Ray Approximation

First order additional terms of the ray method are used to calculate the displacement vector in region in which the zeroorder ray method does not give correct results. Specifically, nearly normal PS reflections are studied, for which the zeroorder ray method gives negligible or zero amplitudes. Use of the first-order additional terms leads to the results comparable with other more precise methods, with very modest additional computational requirements. Examples are shown of the application of the approach to simple isotropic models including constant gradient models and models with curved interfaces.