National Centers for Environmental Information (NCEI)
MULTICHANNEL SEISMIC-REFLECTION PROFILES
Aleutian Arc and Trench, Alaska
USGS Open File Reports 88-502 and 89-202*
Data Announcement 89-MGG-06
In June and July 1980 and again in July and August 1981, the
U.S. Geological Survey (USGS) conducted reconnaissance surveys
from 171 degrees W to 173 degrees E longitude along the Aleutian
Arc and Trench near the islands of Atka, Amlia, Kiska, Agattu and
Seguam. A total of 2880 km of 24-channel seismic-reflection data
were collected on the USGS Research Vessel S.P. Lee (USGS cruise
identifiers L5-80-AA and L9-81-AA). These profiles for purchase from the National Geophysical Data Center (NGDC) (now the National Centers for Environmental Information (NCEI)).
Seismic energy was provided by a tuned array of five airguns
with a total volume of 1212 cubic inches of air (L5-80-AA) or
1301 cubic inches of air (L9-81-AA) compressed to 1900 psi. The
recording system during both cruises consisted of a 24-channel,
2400 meter streamer with a group interval of 100 m, and a GUS
(Global Universal Science) model 4200 digital recording
instrument. A shooting geometry of 50-m shotpoint intervals with
100-m group intervals resulted in a 24-fold data collection.
Navigational control for the survey was provided by a Magnavox
integrated navigation system using satellites fixes, doppler-
sonar and during cruise L5-80-AA, Loran-C (Rho-Rho). A 2-
millisecond sampling rate was used in the field; the data were
later resampled to 4-milliseconds during the demultiplexing
process. Record lengths of 8 to 16 seconds were used which,
combined with a deep water delay, yielded up to 16 seconds of two
way travel time. Processing was done at the USGS processing
center in Menlo Park, California, in the sequence: editing-
demultiplexing, velocity analysis, CDP stacking, deconvolution-
filtering, and plotting on an electrostatic plotter. The seismic
lines are available on plastic, paper sepia, paper blackline, and
* "Multichannel Seismic-Reflection Profiles Collected in 1980
across the Aleutian Arc and Trench, Alaska" By D.M. Mann, D.W.
Scholl and R.W. Sliter, U.S.G.S. Open File Report 89-202, U.S.
Geological Survey, Menlo Park, California.
"Multichannel Seismic Reflection Profiles Collected in 1981
across the Aleutian Arc and Trench, Alaska" By D.W. Scholl, D.M.
Mann, T.L. Vallier and R.W. Sliter, U.S.G.S. Open File Report 88-
592, U.S. Geological Survey, Menlo Park, California.
DATA AVAILABLE (please refer to 9-digit product numbers when
multichannel seismic-reflection profiles (24 lines, 34 sections)
(plastic sepia) Product #976F20174
(paper sepia) Product #976F19174
(blackline) Product #976F18174
3 trackline charts (scale: 1:500,000). Product #976F18174
1 magnetic tape containing shotpoint navigation, magnetics,
bathymetry and gravity. Product #976H07174. This is also
available on CD-ROM, Product #129F27001.
24 digital magnetic stack tapes (not deconvolved or band-pass
filtered, Phoenix format). Product #967L07174.
24 digital magnetic demultiplexed tapes (edited for missed shots
and muting times, Phoenix format - modified S.E.G.-X 32 bit
floating point). Product #976L07175.