National Centers for Environmental Information (NCEI)

MULTICHANNEL COMMON DEPTH POINT (CDP)
SEISMIC REFLECTION DATA
LINES IPOD, A & B - CAPE HATTERAS TO THE MID-ATLANTIC RIDGE

Data Announcement 1978-Q

The U.S. Geological Survey (USGS) and the National Science Foundation (NSF) have recently made a CDP data set available to the National Geophysical Data Center (now the National Centers for Environmental Information)for public dissemination. These data were collected for USGS/NSF in 1974 by Digicon, Inc., on the M/V GULF SEAL, as part of the International Program of Ocean Drilling (IPOD). The field and processing efforts were under the direction of the IPOD Site Survey Management Office at Lamont-Doherty Geological Observatory and the USGS (Woods Hole, Mass.). Portions of these data were processed in 1975 by the Geophysical Services, Inc.; these portions contain approximately 1,825 km of data from Cape Hatteras heading southeast across the Blake Plateau.

The data are available in numerous formats including: (A) sepia and blackline reproduction packages, (B) microfilmed records, and (C, D) computerized data on magnetic tape.

A.  SEPIA AND BLACKLINE REPRODUCTION PACKAGES

These data packages include CDP sections processed as follows:

                                          COVERAGE BY SHOT POINTS

PROCESSING TECHNIQUE           IPOD        LINE A          LINE B

(1) Scaled section         101-12,000      83-263          83-700
                           21,230-22,690
                           27,910-28,910
                           32,200-34,110

(2) True amplitude section 101-1,023       83-263          83-700

(3) Depth section          101-12,000      83-263          83-700

(4) Migrated depth section 700-1,200

(5) Migrated time section  1,539-2,160*
                           4,300-4,450*

*  Available only for full-scale sets.

The data are offered as a complete set or as separate
geographical packages:

    I.  Continental Shelf, Slope, and Upper Rise - containing
        Line A, Line B, and IPOD shot points 101-3,277.

   II.  Lower Continental Rise to Bermuda Rise - containing IPOD
        shotpoints 3,240-12,000.

  III.  Mid-Atlantic Ridge - containing IPOD shot points
        21,230-22,690; 27,910-28,910; and 32,200-34,110.

The information below is available in sepia or blackline in half
scale* or full scale*.

Part I:  Continental Shelf - Upper Rise

Part II:  Lower Continental Rise-Bermuda Rise

Part III:  Mid-Atlantic Ridge


*See notes below:

                                        Full Scale    Half Scale

True amplitude and scaled sections     2.5 in./sec   1.25 in./sec
                                        24 tr./in.     48 tr./in.

Depth sections                        1.66 in./km    0.83/in /km
                                      1.21 km/in.    2.42 km/in.
                                        24 tr./in.     48 tr./in.

Included with these packages are:

           - Track charts of shot-point data (1:500,000);
           - Navigation listing (microfiche) - note:  Navigation
               also available on magnetic tape;
           - Velocity profiles (on microfilm).

B.  MICROFILM COPIES

The CDP sections, track charts, and velocity profiles are
available on microfilm.  (Includes 1 reel of CDP sections/maps
and 1 reel of velocity profiles).

C.  SHOT POINT/NAVIGATION TAPES

The shot point/navigation data are available on magnetic tape and
CD-ROM.

Please specify 7- or 9-track, tape density and blocking factor
(5,120 characters or less; unblocked tapes are also available).

D.  CDP TAPES

The data are available in a computerized format. Prices vary depending on the number of tapes ordered.