SHALLOW VELOCITY-DEPTH MODEL IMAGING BY REFRACTION TOMOGRAPHY

A tomographic imaging technique combined with coherence inversion is p roposed for constructing a near-surface model from refraction events. A model obtained from coherence inversion serves as a good background model for the tomographic reconstruction. A simultaneous iterative rec onstruction technique (SIRT) algorithm was used for this purpose. This is a simple algorithm and can be easily adapted to irregular acquisit ion geometry and limited angular aperture. Using synthetic data it was shown that the proposed procedure can be used for determination of lo cal velocity anomalies in a shallow subsurface. The technique was also tested on a real data set.