National Centers for Environmental Information (NCEI)

MULTICHANNEL COMMON DEPTH POINT (CDP)
SEISMIC REFLECTION DATA

Additional Atlantic Survey Lines

Data Announcement 1980SE-BB

The National Geophysical Data Center (now the National Centers for Environmental Information) is making available CDP seismic reflection data for lines 18 through 38 from Atlantic coastal areas. These data were collected as part of a program by the U.S. Geological Survey (USGS) to survey the geological framework of the United States coastal areas.

During 1978, USGS contracted with Geophysical Services, Inc. (GSI), for GSI to collect 4,813 km of 48-channel seismic reflection profiles along the continental margin between North Carolina and Maine. Fifteen lines were acquired perpendicular to the margin (lines 18 through 32) and six lines were acquired parallel to the margin (lines 33 through 38). The data were collected on the Motor Vessels CARINO and CECIL GREEN between May and November 1978. Tuned airgun arrays totaling 2,000 and 1,400 in(cubed) of air were used by the respective vessels. A 3,600-m- long hydrophone streamer was used by both ships.

The profiles were stacked by GSI and displayed in conventional time-variant scaled format to 12 sec of recording time with vertical scales of 2.5 in/sec and horizontal scales of 1.2 km/in. Additional processing was applied to Line 25 across the Baltimore Canyon Trough and Line 32 across Carolina Trough. Data collected along line 25 over the Outer Shelf, Slope, and Upper Rise were restacked with 1 1/2-km spaced velocity analyses, signature deconvolution, deep-water multiple deconvolution, velocity filtering (on shelf only), and time migration. The restacked part and remaining parts of Line 25 were converted to depth sections having a vertical scale of 1.2 km/in (vertical exaggeration: 2/1). Data collected along two parts of line 32 were also restacked with signature and deep-water multiple deconvolution. Line 32 was also converted to a depth section except for the first 80 km near shore.

DATA AVAILABILITY

Lines 18-38 are available (per line) in blackline, paper sepia, and plastic sepia. The data for these lines includes 92 charts, 4 reels of microfilm (1246-1249), and 1 OFR (#80-834).

The following documentation is provided with each line:

      - location maps (sepia or blackline)
      - velocity profiles (microfilm)
      - shot-point listings (microfilm)
      - copy of supportive USGS Open File Report

The shot-point locations are also available on magnetic tape. Unless specified otherwise, tapes will be 9-track, 1600 bpi.

CDP data are also available on magnetic tape.