Seismic ray theory for lithospheric structures with slight lateral variations

b In this paper, the method of small perturbations is applied to the ray and energy transport equations in an investigation of the effect of weak inhomogeneities on the propagation of seismic rays through a layer of fixed thickness. Just as Aki et al. have used travel‐time residuals to infer first‐order velocity perturbations in their block‐modelling procedure, it is proposed that surface slowness and amplitude data may be used to give additional information about the structure of the velocity perturbations beneath the observer. Copyright © 1980, Wiley Blackwell. All rights reserve