Numerical technique for studying surface waves appearing under the motion of a submarine land-slide is discussed. This technique is based on the application of the model of a quasi-deformable landslide and two shallow water models, namely, the classic (dispersion free) one and the completely nonlinear dispersivemodel of the second hydrodynamic approximation. Numerical simulation of surface waves generated by a large model landslide on the continental slope of the Black Sea near the Russian coast is performed. It is shown that the dispersion has a significant impact on the picture of propagation of tsunami waves on sufficiently long paths.