National Geophysical Data Center
Multichannel Seismic-Reflection Data
Bathymetry and Potential Field Data
Central and Northern New Hebrides Island Arc
Vanuatu to the Solomon Islands, Southwest Pacific
U.S.G.S. Open File Report 90-280*
Data Announcement 91-MGG-02
The U.S. Geological Survey conducted a geophysical survey in 1984
in the central and northern parts of the New Hebrides Arc with
the R/V S.P. LEE (cruise identification L5-SP-84). These data
are now available for purchase from the National Geophysical Data
Approximately 2400 km of 24-fold multichannel seismic reflection
data were collected along 37 lines. The seismic source consisted
of a tuned, 5 airgun array totaling 1426 cubic inches,
pressurized to 2000 psi, towed at a depth of approximately 10
meters. Individual gun volumes were usually 148, 194, 309, 309,
and 466 cubic inches. The receiver consisted of a 24 channel
hydrophone streamer with 100 meter group lengths containing 60
hydrophones in each group. The near channel offset from the
airguns was 297 m and far channel offset 2611 m. The data were
recorded with a Gus Model HDDR-4200 recording system. Shots were
fired every 50 meters and records were sampled in the field at a
2 millisecond rate prior to processing. Primary navigation was
The basic data processing sequence was editing-demultiplexing,
static corrections, CDP sort, velocity analysis, and correction,
stacking, and plotting on an electrostatic plotter. Particular
attention was devoted to accurate velocity estimation through the
use of a standard semblance plots and constant velocity stacks.
The semblance velocity analyses were performed every 2.5 km (50
CDP's) along each line, using a summation of 3 to 5 adjacent CDP
gathers for each analysis. The seismic lines are available on
plastic, paper sepia, paper blackline, and magnetic tape.
Digital geophysical data from this cruise are also available. To
complement the seismic data, there are 2548 nautical miles of
bathymetric data, 2067 nautical miles of magnetic data, and 2225
nautical miles of gravity data. The data are formatted in the
standard MGD77 format and available as 1600 or 6250 bpi and in
ASCII OR EBCDIC code tapes.
* Greene, H.G., Macfarlane, A., Smith, G.L., and Geist, E.L.,
Multichannel Seismic-Reflection Profiles from Vanuatu to the
Solomon Islands collected in 1984, Open File Report 90-208, U.S.
Geological Survey, Menlo Park, California.
DATA AVAILABLE (Please refer to 9-digit product numbers when
42 multichannel seismic-reflection profiles for 37 lines
(plastic sepia) Product #976F20178
(paper sepia) Product #976F19178
(blackline) Product #976F18178
3 trackline charts (scale: 1 3/8 inches = 10 nautical miles)
1 magnetic tape containing shotpoint navigation, magnetics,
bathymetry, and gravity. Product #976H07178. This is also
available on CD-ROM, Product #129F27001.
37 digital stacked tapes in SEG-Y format. Product #976L07178
Please contact NGDC for prices.