Use Of Wavefront Curvature To Relate Seismic Data With Subsurface Parameters

A Dix-type formula relating the normal moveout velocity (VNMO) to the parameters of a two-dimensional, dipping bed, multilayered model of the earth is discussed. The formula results from (1) showing that the VNMO is related to the radius of curvature of the wavefront emerging at the surface after reflection from some interior horizon, and (2) expressing this radius in terms of the parameters of the earth model. An example with severely dipping layers is used to compute the VNMO from the formula, which is then compared to the value of moveout velocity obtained from a synthetic velocity gather generated at the same point in the model.