The Kidd Creek crosswell data were collected by Noranda Mining and Exploration using boreholes drilled from inside the copper-zinc sulfide mine. The boreholes intersect an ore body as evidenced by cores from each hole. These seismic data are ideally suited for the reduced-time migration method since there exists an unknown time delay and/or well location error in the seismograms. In an attempt to mitigate the problem Hu (1999) proposed that a constant time shift be applied to the traces. He estimated this delay to be 3.5 milliseconds by assuming a constant background velocity and minimizing the data residual. After applying the data time shift, the first arrival traveltimes were inverted to generate the velocity model shown in figure 4.1. Since the velocity tomogram does not correlate well with the empirically based model the tomogram is assumed to be in error. Nevertheless, it is used here as the migration velocity model to prove the utility of the reduced-time migration. Since the S-wave first arrivals are not distinct through out the data set they were not picked and inverted to generate an S-wave velocity model. Instead I assume a constant P-to-S velocity ratio of 1.7.