[en] A series of calculations, using a granite equation-of-state (EOS) illustrate the dependence on initial cavity size and on shear strength of parameters commonly used to describe the reduced velocity potential (RVP) and reduced displacement potential (RDP). Calculations for explosions in cavities in granite support both the results of Terhune, et al. (1979) showing enhanced seismic coupling for initial cavities of a few scaled meters radii and the results of King, et al. (1989) showing no enhanced coupling in the hydrodynamic regime for the same initial cavity sizes. Calculations of seismic coupling for tamped explosions with the same granite model except for variations in shear strength show the transition from a strength dominated regime to an overburden dominated regime. When the rock strength is insufficient to prevent a large cavity rebound driven by the overburden stresses, the coupling as measured by the asymptotic RDP value becomes independent of strength. The RDP overshoot parameter appears to be a good indicator of whether this is occurring. It may be a useful parameter to filter the database of seismic records from nuclear explosions when looking for correlations with rock properties