U.S. DEPARTMENT OF THE INTERIOR / U.S. GEOLOGICAL SURVEY
                                
                                
        U.S. GEOLOGICAL SURVEY DIGITAL DATA SERIES DDS-13
                                
              International Phase of Ocean Drilling
                Seismic Line 1 Demultiplexed Data
               Cape Hatteras to Mid-Atlantic Ridge
                                
                            DISC ¯02

Demultiplexed Seismic Data

     Each file of seismic data is the disc-image of a SEG-Y
format tape output during the demultiplexing of the original
field data.  The data were written to tape using the 32 bit IBM
floating point format (Barry, and others, 1975).  As the data
were copied bit-for-bit to the CD-ROM file, this format was
preserved.  Each file of sesimic data is named IPD{number}, where
{number} is the first shotpoint in the file.  NOTE: FFID
indicates the Field File Identifacation Number assigned each shot
as it was recorded.

             file:  ¯IPD600.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯146605440
   traces in file:  ¯15866
      first trace:  ¯999/1 FFID/trace
       last trace:  ¯254/56 FFID/trace


             file:  ¯IPD727.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯144794400
   traces in file:  ¯15670
      first trace:  ¯254/57 FFID/trace
       last trace:  ¯588/40 FFID/trace


             file:  ¯IPD854.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯148647480
   traces in file:  ¯16087
      first trace:  ¯588/41 FFID/trace
       last trace:  ¯768/7 FFID/trace

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             file:  ¯IPD984.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯135711480
   traces in file:  ¯14687
      first trace:  ¯768/8 FFID/trace
       last trace:  ¯4/62 FFID/trace


Observer Logs

     The following files are digitized versions of the original
observer's log sheets.  Each file is named OB{number}.{format},
where {number} is the first shot point on the page, and {format}
is the graphic format of the file: PCX, TIF, or GIF.  No {format}
extensions are shown for the file names given below.

OB561
OB611
OB661
OB711
OB761
OB811
OB861
OB911
OB961
OB1061


REFERENCE

Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended
     standards for digital tape formats: Geophysics, v. 40, p.
     344-352.


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