Digital single-channel seismic-reflection data from Western Santa Monica Basin

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Frequently anticipated questions:

What does this data set describe?

Digital single-channel seismic-reflection data from Western Santa Monica Basin
During a collaborative project in 1992, a Canadian Geological Survey cruise obtained about 850 line-km of high-quality boomer and sleeve-gun reflection profiles across Hueneme, Mugu and Dume submarine fans, Santa Monica Basin, off southern California. The goals of this work were to better understand the processes that lead to the formation of sandy submarine fans and the role of sea-level changes in controlling fan development.
This report includes a trackline map of the area surveyed, as well as images of the sleeve-gun profiles and the opportunity to download both images and digital data files (SEG-Y) of all the profiles.
Additional information for this USGS Coastal and Marine Geology field activity is available online at
  1. How might this data set be cited?
    Normark, William R., Piper, David J.W., Sliter, Ray W., Triezenberg, Peter, and Gutmacher, Christina E., 2006, Digital single-channel seismic-reflection data from Western Santa Monica Basin: USGS Open-File Report USGS OFR 2006-1180, United States Geological Survey, Menlo Park, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -119.50000
    East_Bounding_Coordinate: -118.50000
    North_Bounding_Coordinate: +34.16667
    South_Bounding_Coordinate: +33.50000
  3. What does it look like? (SVG)
    Index map of tracklines covered in this report. (JPEG)
    Example of sleeve-gun seismic data accessible via this report.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 30-Jan-1992
    Ending_Date: 04-Feb-1992
    Time span of data collection (GSC).
  5. What is the general form of this data set?
    Text report containing graphical map images and geophysical data images (no spatial referencing).
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      UTM_Zone_Number: 11
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -117.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 25
      Ordinates (y-coordinates) are specified to the nearest 25
      Planar coordinates are specified in Meters
      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    Locations of data profiles are shown as a map image at an unspecified projection and scale. This Scalable Vector Graphics (SVG) map allows mouse over trackline details and links to profile displays. The images of the reflection profiles are rendered in TIFF and JPEG image formats. Links are provided to the SEG-Y digital data for each line.
    Entity_and_Attribute_Detail_Citation: none

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • William R. Normark
    • David J.W. Piper
    • Ray W. Sliter
    • Peter Triezenberg
    • Christina E. Gutmacher
  2. Who also contributed to the data set?
    Peter Triezenberg produced the interactive web pages for this report.
  3. To whom should users address questions about the data?
    Ray W. Sliter
    United States Geological Survey (USGS) Coastal and Marine Geology (CMG)
    USGS, Mail Stop 999, 345 Middlefield Road
    Menlo Park, CA

    (650) 329-5194 (voice)

Why was the data set created?

These sleeve-gun data were collected as part of a project investigating deep-sea fans. They have subsequently become useful to a current project working to identify the active fault systems in the southern California coastal zone, including the continental shelf and adjacent deep basins, that pose the greatest potential seismic hazards for the most populated urban corridor along the U.S. Pacific margin. See for more information. This report is prepared to make these data available to science researchers, students, and other interested parties.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2004 (process 1 of 4)
    Refer to report sections "Data acquisition method" and "Data processing" for details of geophysical data acquisition and processing sequence used for data in this report. Ray W. Sliter
    Date: 2005 (process 2 of 4)
    Plotted shot point map of cruises using GMT to create sub-maps. Converted plots to TIFF and JPEG files to provide format options for downloading data. Ray W. Sliter
    Date: 2006 (process 3 of 4)
    Used GEODAS (GEOphysical DAta System) to create a custom bathymetric and topographic grid for the southern California region covered by the cruise index map. The website is: The parameters used are as follows: Grid database: US Coastal Relief Model Grids Lat/Lon Area Bounds: 34.16667 N to 33.50000 N, 119.50000 W to 118.50000 W Grid Cell Size: 3 seconds Grid Cell Value Parameters: 4-byte integers, 10ths of meters Grid Format: xyz (lon, lat, depth) format, no header, space-delimited, exclude empty cells. Peter Triezenberg
    Date: 2006 (process 4 of 4)
    Plotted tracklines of seismic reflection profiles using GMT to create maps. Created Scalable Vector Graphics (SVG) map to allow mouse-over of trackline details and links to profile displays. Peter Triezenberg
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Data have not been independently verified.
  2. How accurate are the geographic locations?
    Shot point numbers in the data files correspond to those in the navigation files. The horizontal positional accuracy of the seismic data thus linked to ship's position is estimated to be within 30 meters. See Appendix for details of navigational system used.
  3. How accurate are the heights or depths?
    Depths shown in the seismic data files are in milliseconds (round trip travel time) and are referenced to sea level.
  4. Where are the gaps in the data? What is missing?
    Reference the full report for a description of data coverage. All sleeve-gun data collected on the referenced cruise have been included in this report. Some seismic profiles have gaps in them due to system crashes or hardware maintenance.
  5. How consistent are the relationships among the observations, including topology?

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
These data are not intended for navigational purposes. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  1. Who distributes the data set? (Distributor 1 of 1)
    Ray W. Sliter
    United States Geological Survey (USGS) Coastal and Marine Geology (CMG)
    USGS, Mail Stop 999, 345 Middlefield Road
    Menlo Park, CA

    (650) 329-5194 (voice)
  2. What's the catalog number I need to order this data set? United States Geological Survey Open-File Report 2006-1180 This report is distributed on-line only. Access it at
  3. What legal disclaimers am I supposed to read?
    Please recognize the U.S. Geological Survey (USGS) as the source of this information.
    Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.
    Neither the U.S. Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.
    Trade, firm, or product names and other references to commercial products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy.
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 26-Jun-2006
Metadata author:
Ray W. Sliter
United States Geological Survey (USGS) Coastal and Marine Geology (CMG)
USGS, Mail Stop 999, 345 Middlefield Road
Menlo Park, CA

(650) 329-5194 (voice)
Metadata standard:
Content Standard for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)

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