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National Centers for Environmental Information (NCEI)


Northern California and Oregon-Pacific OCS

SGS Open File Report 86-406*

Data Announcement 87-MGG-03

Approximately 2,233-km of 24-channel common depth point (CDP) seismic-reflection profiles for purchase from the National Geophysical Data Center (NGDC) (now the National Centers for Environmental Information (NCEI)) for the Pacific Outer Continental Shelf off northern California and Oregon. The profiles were collected on the U.S., Geological Survey (USGS) R/V S.P. LEE Cruise No. L477NC during May 1977.

A sound source of five airguns with a volume of 1,326 of air compressed to approximately 32,000 psi were used. The recording system consisted of a 24-channel, 2,400-m-long streamer with a group interval of 100 m, and a GUS (Global Universal Science) model 4200 digital recording instrument. Shots were fired every 50 m. Navigational control for the survey was provided by a Marconi integrated navigation system using transit satellites and Doppler sonar augmented by Loran C (Rho Rho). A 2-msec sampling rate was used in the field. The data were later desampled to 4 msec during the demultiplexing process. Record lengths vary from 5 to 9 sec of data below the seafloor. Processing was completed in the sequence: editing-demultiplexing, velocity analysis, CDP stacking, deconvolution filtering, and plotting on an electrostatic plotter.
* Multichannel Seismic-Reflection Profiles Collected in 1977 off of the Northern California and Oregon Coast", by Davis S. McCulloch, Dennis M. Mann, Holly F. Ryan, and Ray W. Sliter, USGS Open File Report 86-406, United States Geological Survey, Menlo Park, California.


1. Common-Depth-Point Seismic Data

    24-fold multichannel seismic data for 43 lines/47 sections. Available in plastic sepia, paper sepia, and blackline.

    1 Navigation chart available in plastic sepia, paper sepia, and blackline.

    1 Shot-point navigation magnetic tape (9-track, 1600 bpi, ASCII). This is also available on CD-ROM.

2. CDP Stack Tapes

    43 Digital magnetic stacked tapes derived from velocity analysis. (Not deconvolved or bandpass filtered. Copies of tapes and description of tape format available.

    43 Digital magnetic demultiplexed stacked tapes