f Building complex geologic models by recursively merging the parts

A geologic model of an exploration target is usually complex, containing spatially variant velocities, and surfaces across which the lithology may be discontinuous. These complex features are not revealed en masse, but are discovered individually as seismic imaging uncovers them. For example, a salt structure is usually imaged first with a sediment-only model, then with the top-of-salt added, then with the bottom-of-salt added. Correspondingly , a geologic modeling facility should accommodate this piecemeal addition of detail to the model.