MGL1109 Chirp - US Extended Continental Shelf Project: Gulf of Alaska CHIRP high-resolution Seismic Profile data.

The Knudsen 2620 acquired sub-bottom profiles continuously throughout the cruise. The Knudsen was operated in 3.5 kHz Chirp mode, emitting a 1.5 kHz to 5 kHz (3 kHz bandwidth centered on 3.5 kHz) pulse from transducers mounted in the pod beneath the hull. A record window of 200 meters and assumed sound velocity of 1500 m/s remained constant through the cruise. The resulting data records were 267 msec long, with a sample interval 0.16667 msec (6 kHz). The ping rate varied over the course of the cruise. For most of the first two weeks, the ping rate was approximately 5 seconds. On or about June 23, the ping rate was increased to approximately 2 seconds.
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  • gov.usgs.mgl1109mcs
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Distribution Formats
  • Raw Knudsen SEG-Y Datagram
    • File Compression: None (transfer size in MB)
Distributor User Services
DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Dataset author Dr. Ginger Barth
United States Geological Survey
Dataset Principal Investigator Dr. Ginger Barth
United States Geological Survey
Time Period
Spatial Reference System urn:ogc:def:crs:EPSG::4326urn:ogc:def:crs:EPSG::5831
Spatial Bounding Box Coordinates
N: 57.78363
S: 53.18759
E: -138.18889
W: -153.01673
Spatial Coverage Map
Documentation links not available.
Publication Dates
  • creation: 2011-06-07
Dataset Progress Status Status not available
Data Update Frequency Data update frequency not available
Purpose The purpose of this field program was to determine sediment thickness and velocity structure, stratigraphic architecture, and basement structure of the North Pacific seafloor in support of requirements for continental shelf maritime zone definition in the Gulf of Alaska. The program was focused on the geologic structures and dynamic processes that control the distribution of sediment, including the manner in which the processes of the slope meet the deep sea floor, and the places where sediment is thickest due to the coincidence of basement depressions and abundant sediment supply. The survey explored portions of the Surveyor and Baranof sedimentary systems, the Aja Fracture Zone and the Kodiak Bowie seamount corridor.
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
Theme keywords ProcessedMethod Keywords
  • Seismic:Reflection
ProcessedDataClass Keywords
  • Other
Global Change Master Directory (GCMD) Service Keywords
Data Center keywords Global Change Master Directory (GCMD) Data Center Keywords
  • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
  • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
Place keywords
  • [1137] Gulf of Alaska
  • [1139] Aja Fracture Zone
  • [1141] Surveyor Fan
  • [1140] Kodiak Bowie Seamount Corridor
  • [1138] Baranof Fan
Keywords DataType Keywords
  • Seismic:Active:Subbottom
Keywords SeismicDataProvenance Keywords
  • DigitalSeg:DigitallyAcquired
Use Constraints No constraint information available
Access Constraints
  • openRelease Date: 2011
Fees Fee information not available.
Lineage information for: dataset
Lineage Statement Data Quality: The Knudsen operated continuously through the entire cruise, with only minor (on the order of minutes) data gaps. For the first two weeks of the cruise the Knudsen operated at a ping rate of approximately 5 seconds. For the final 4 or 5 days, the ping rate was reduced to approximately 2 seconds. The higher ping repetition rate improved the lateral resolution on the sub-bottom images.
Lineage information for: repository
Processing Steps
  • 2015-04-22T00:00:00 - NOAA created the National Centers for Environmental Information (NCEI) by merging NOAA's National Climatic Data Center (NCDC), National Geophysical Data Center (NGDC), and National Oceanographic Data Center (NODC), including the National Coastal Data Development Center (NCDDC), per the Consolidated and Further Continuing Appropriations Act, 2015, Public Law 113-235. NCEI launched publicly on April 22, 2015.
Acquisition Information (collection)
  • Knudsen 2620
  • Kongsberg EM122
  • Marcus G. Langseth
Last Modified: 2017-12-21
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