Introduction

Tomographic methods are needed for estimating a velocity model that varies rapidly along the lateral direction. In previous reports I presented the theory (Biondi, 1988) and the synthetic results (Biondi, 1989) of a velocity-estimation method capable of reconstructing velocity anomalies shorter than the cable's length. In this report I present the results of applying the method to the problem of estimating a velocity anomaly from a real data set.

The data set is particularly interesting for testing a velocity-estimation method because the velocity anomaly is shorter than the cable's length and it is not located near the surface but it is centered at a depth of about 1.5 kilometers. Therefore both the lateral and the vertical resolution of the estimation method are tested by the problem presented by the data. Furthermore the pull-down in the reflections caused by the anomaly can be corrected only if a good velocity model is used as an input for depth migration.