Despite theoretical advancements in multiple identification and elimination, the application and success of these advancements are questionable in some cases and are limited to marine environments, especially deepwater. In land seismic, however, a clear understanding of the internal multiple generators is not readily available; thus, efforts to attenuate them often are quite ineffective. We have analyzed, in the case of many thin layers, how the primaries and multiples are affected by fine-scale variations in the velocity model. Cross-coherence is used to measure the similarity of the original primaries/multiples and the ones generated from upscaled velocity models. The combined use of kurtosis and the cross-coherence method enables us to precisely quantify the impact of fine layering on multiples. Test results demonstrate that surface-related multiples and internal multiples are much more sensitive than the primaries to thickness variations of the velocity model. As the thickness of each upscaled layer varies from 1 to 21 m, multiples change rapidly, whereas primaries are almost the same. The high sensitivity of internal multiples on fine layering suggests that the detailed model information should be considered in model parameterization in the internal multiple removal, especially for model-driven methods.