National Centers for Environmental Information (NCEI)

MULTICHANNEL COMMON DEPTH POINT (CDP) DATA
Florida to New Jersey - Atlantic OCS

Data Announcement 83-MGG-17

    Multichannel Common Depth Point (CDP) data for 17 lines totaling approximately 1,241-line-km are available from the National Geophysical Data Center (NGDC) (now the National Centers for Environmental Information (NCEI)). The data were collected in June and July 1979 on the Atlantic Outer Continental Shelf from Florida to New Jersey by the Seismic Division of Whitehall Corporation under Contract No. 14-08-0001-16330 to the U.S. Geological Survey (USGS) Conservation Division, now the Minerals Management Service, U.S. Department of the Interior.

    A 21-airgun tuned-array marine acoustic source with a total gross volume of 2,183 cu. in. was used in this survey. The tuned system consisted of three sub-arrays having volumes of 182 cu. in. was used in this survey. The tuned system consisted of three sub-arrays having volumes of 182 cu. in., 708 cu. in., and 1293 cu. in. The 21 guns were towed astern in two parallel strings 65 ft apart. The gun group on each string was 75 ft overall with the nearest gun 80 ft form the ship's stern. The CDP data, available as hard copy in either sepia or blackline, consist of 25 sections of both true relative records and scaled sections, giving a total of 69 individual records. The average line length is 75 km. In addition, two survey reports, 25 velocity profiles, single-trace seismic profiles and fathometer records are contained on one reel of 35-mm microfilm.

    Navigational positions were achieved by an integrated Satellite-Doppler-Sonar Magnavox MX-200 system. Basic position reference was obtained from the U.S. Navy Navigation Satellite System, with fixes available every 60 to 90 min. Loran-C was integrated with the SatNav positions. Nineteen post-plot maps are scaled on UTM grids of 1:96,000 or 1:500,000. "Tic" marks at every 80,000 ft are annotated along with latitude/longitude tics at every 30 min of arc. Fifteen maps show shot-point locations for lines D M V G F. Four maps indicate locations of the CH lines. Labeling of the points on the maps is at 50-shot (2,500 m) intervals.

    A digital magnetic tape containing latitude, longitude, time, and date for every plotted point is also available. The magnetic tape contains every 10th point on each line at an interval of 500 m. Magnetic tape specifications are in modified U.K. Offshore Operators Association (UKOOA) format, IBM compatible, 9-track, 1600 EBCDIC-character coding, odd parity, record length 80 bytes followed by an inter-record gap. The tape is divided into two parts: a 4-record header and a multi-record shot-point data section. Format specifications are provided.

DATA AVAILABLE

The following data is availabe in plastic sepia, paper sepia, and blackline:

    25 sections Common Depth Point Seismic Profiles
    15 Shot-Point Maps (scale: 1:96,000)
    4 Shot-Point Maps (scale: 1:500,000)

The following data is available in 35-mm microfilm:

    1 Reel (No. 2046) microfilm. Contains survey reports, trace and velocities.

    1 Navigation magnetic tape/cdrom and documentation.