This paper describes the use of a wavefront reinforcement model which
has been developed to supplement established charge mass scaling
methods. The model allows for the time taken for blast vibration
wavefronts to travel from each blasthole, and has been successfully used
to explain the reason for directional increases in both air and ground
vibration in certain situations. The model has been used to identify
wavefront reinforcement due to the propagation of air vibration and
ground vibrations in certain situations. The paper includes a throw (or
cast) blasting case history which provides multi-station evidence of the
strong directional nature of wavefront reinforcement.