The source for the seismic reflection data collected during Leg 197 was an 80-in3 Seismographic Services Inc. water gun. These data were received by a single-channel streamer and collected at slow survey speeds that resulted in shot intervals of 15–20 m. The high-frequency content of the water gun, coupled with the small shot spacing, provided high vertical and lateral resolution in the data.
USGS data employed an 80-in3 conventional air gun source and was received by a two-channel streamer with shot intervals between 40 and 50 m. The active sections of the streamer were towed 400 m behind the air gun (S. Dadisman, pers. comm., 2005; see walrus.wr.usgs.gov/infobank/f/f287aa/html/f-2-87-aa.meta.html).
All data were processed using Landmark Graphics ProMAX 3D software on a 750-MHz Sun Blade 1000 workstation. Source-signature deconvolution (discussed below) was performed on an 866-MHz Pentium III using Parallel Geoscience SPW software. The processing sequence for all data sets included a –100-ms static shift, normal moveout (NMO) corrections, deconvolution, bandpass filtering, true amplitude recovery, water column mute, trace kill, and Stolt F-K migration. Refer to Table T1 for a detailed description of processing parameters for each survey. A constant velocity of 1500 m/s was used for NMO, true amplitude correction, and migration.