Two-dimensional computer calculations were performed to model nuclear and high-explosive cratering detonations in saturated Bearpaw clay shale. Three calculations simulated 20-ton energy-yield nitromethane cratering experiments at burial depths of 6, 12.5, and 17 m. Results agreed with experimentally measured peak stresses, peak particle velocities, and crater dimensions. Calculations for a hypothetical nuclear source of the same energy at 12.5 m showed that only half as much kinetic energy was coupled into the mound; a correspondingly smaller crater was predicted. A 10-ton nitromethane source at 12.5 m was also calculated and was found to closely match the nuclear calculation. For these calculations, mound kinetic energy provided a valid criterion for achieving cratering similitude between high-explosive and nuclear events. In this case, similitude was obtained with a nitromethane source having about half the energy of the nuclear source.