The reflection coefficient, needed to generate the synthetic seismograms, was calculated from the check shot-corrected velocity data and the density data for each site. The resultant files were converted to log ASCII standard (LAS) format and input into ProMAX, where the data were converted from depth to time.
MCS data for each of the three sites were collected on the Maurice Ewing in 1995 using a 20 air-gun tuned source array and a 5-km streamer (Goodliffe et al., 1999). The seismic source signal was derived separately for each of the three sites from the stacked and migrated data proximal to each site. Using ProMAX, the seafloor at each site was flattened along the negative-to-positive transition directly before the first positive peak associated with the seafloor. The traces were stacked, and the portion of the signal from the first break to a point interpreted as the end of the source signal, typically ~100 ms, was extracted. The source signal was convolved with the reflection coefficient, and the resultant synthetic seismograms were output with automatic gain control (AGC) applied (200 ms). No attempt was made to include the effects of peg-leg multiples.