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U.S. Geological Survey
Open-File Report 2005-1084

Multichannel seismic-reflection data acquired off the coast of southern California – Part A 1997, 1998, 1999, and 2000.
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Frequently-anticipated questions:

What does this data set describe?

Title:
Multichannel seismic-reflection data acquired off the coast of southern California - Part A 1997, 1998, 1999, and 2000
Abstract:
Multichannel seismic-reflection (MCS) data were collected in the California Continental Borderland as part of southern California Earthquake Hazards Task. Five data acquisition cruises conducted over a six-year span collected MCS data from offshore Santa Barbara, California, south to the Exclusive Economic Zone boundary with Mexico. The primary mission was to map late Quaternary deformation as well as identify and characterize fault zones that have potential to impact high population areas of southern California. To meet its objectives, the project work focused on the distribution, character, and relative intensity of active (i.e., Holocene) deformation along the continental shelf and basins adjacent to the most highly populated areas. In addition, the project examined the Pliocene-Pleistocene record of how deformation shifted in space and time to help identify actively deforming structures that may constitute current significant seismic hazards.

The MCS data accessible through this report cover the first four years of survey activity and include data from offshore Malibu coastal area west of Santa Monica, California, to the southern survey limit offshore San Diego. The MCS data, which were collected with a 250-m-long, 24-channel streamer used a small gas-injector airgun source. This system provided optimum resolution of the upper 1 to 2 km of sediment for mapping active fault systems. The report includes trackline maps showing the location of the data, as well as both digital data files (SEG-Y) and images of all of the profiles.

Supplemental_Information:
Additional information for these USGS Coastal and Marine Geology field activities is available online at
<http://walrus.wr.usgs.gov/infobank/s/s197sc/html/s-1-97-sc.meta.html>,
<http://walrus.wr.usgs.gov/infobank/a/a198sc/html/a-1-98-sc.meta.html>,
<http://walrus.wr.usgs.gov/infobank/o/o199sc/html/o-1-99-sc.meta.html>, and
<http://walrus.wr.usgs.gov/infobank/a/a100sc/html/a-1-00-sc.meta.html>.

  1. How should this data set be cited?

    Sliter, Ray W. , Normark, William R. , and Gutmacher, Christina E. , 2005, Multichannel seismic-reflection data acquired off the coast of southern California - Part A 1997, 1998, 1999, and 2000: USGS Open-File Report USGS OFR 2005-1084, United States Geological Survey, Menlo Park, California.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -119.00000
    East_Bounding_Coordinate: -117.00000
    North_Bounding_Coordinate: +34.16667
    South_Bounding_Coordinate: +32.50000

  3. What does it look like?

    <http://pubs.usgs.gov/of/2005/1084/maps/scal.html> (JPEG)
    Index map of area covered in this report.
    <http://pubs.usgs.gov/of/2005/1084/maps/o199/lines/221.html> (JPEG)
    Example of Multichannel seismic data accessible via this report.

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 01-Aug-1997
    Ending_Date: 01-Oct-2000
    Currentness_Reference: Time span of data collection and initial archiving.

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form:
    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
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 11
      Transverse_Mercator:
      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?

    Entity_and_Attribute_Overview:
    Locations of data profiles are shown as color-coded map images at an unspecified projection and scale. These HTML image maps allow 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)

    • Ray W. Sliter
    • William R. Normark
    • 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)
    Geophysicist
    USGS, Mail Stop 999, 345 Middlefield Road
    Menlo Park, CA 94025-3561
    USA

    (650) 329-5194 (voice)
    rsliter@usgs.gov

Why was the data set created?

These MCS data were collected as part of a project 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 <http://walrus.wr.usgs.gov/cabrillo/tierra/index.html> 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: 2003 (process 1 of 4)
    Refer to report sections "Cruise history", "Data acquisition methods", and "Data processing" for details of geophysical data acquisition and processing sequence used for MCS data in this report. Ray W. Sliter

    Date: 2004 (process 2 of 4)
    Plotted shot point map of cruises using GMT <http://gmt.soest.hawaii.edu/> to create sub-maps. Broke area into four sections for better viewing. Converted plots to TIFF and JPEG files for zooming in on sections. Ray W. Sliter

    Date: 2004 (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: <http://www.ngdc.noaa.gov/mgg/geodas/geodas.html>.
    The parameters used are as follows:
    Grid database: US Coastal Relief Model Grids
    Lat/Lon Area Bounds: 34.16667 N to 32.50 N, 119.0 W to 117.0 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: 2005 (process 4 of 4)
    Plotted tracklines of seismic reflection profiles using GMT <http://gmt.soest.hawaii.edu/> to create maps. Created HTML image maps 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?

    Tracklines shown are for the GPS antenna on the ships collecting the multichannel seismic data. 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 40 meters.

  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 MCS data collected on the referenced cruises have been included in this report, with the exception of those collected in Los Angeles Harbor and shelf, for an aquifer study, on A-1-00-SC. Some seismic profiles have gaps in them due to system crashes or intentional shutdowns as required, under terms of our operating permit, to protect marine mammals.

  5. How consistent are the relationships among the observations, including topology?

    Undetermined.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
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)
    USGS, Mail Stop 999, 345 Middlefield Road
    Menlo Park, CA 94025-3561
    USA

    (650) 329-5194 (voice)
    rsliter@usgs.gov

  2. What's the catalog number I need to order this data set?

    United States Geological Survey Open-File Report 2005-1084 This report is distributed on-line only. Access it at <http://pubs.usgs.gov/of/2005/1084/>.

  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?

Dates:
Last modified: 16-Mar-2005
Metadata author:
Christina E. Gutmacher
United States Geological Survey (USGS)
Geologist
USGS, Mail Stop 999, 345 Middlefield Road
Menlo Park, CA 94025-3561
USA

(650) 329-5309 (voice)
cgutmacher@usgs.gov

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

Generated by mp version 2.8.11 on Wed Mar 16 13:51:36 2005

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