Marine Seismic Reflection Profiles Data of San Francisco Bay Area

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Frequently anticipated questions:

What does this data set describe?

Marine Seismic Reflection Profiles Data of San Francisco Bay Area
Dataset consists of two-dimensional marine seismic reflection profile data from the San Francisco Bay area. These data were acquired in 1997, with the vessel Davidt Johnston. The USGS identifier for these data is J497SF.
For more information on the seismic surveys see
These data are also available via GeoMapApp ( and Virtual Ocean ( earth science exploration and visualization applications.
Seismic reflection profiles are acquired by means of an acoustic source (usually generated electromagnetically or with compressed air), and a hydrophone or hydrophone array. Both elements are typically towed in the water behind a survey vessel. The sound source emits a short acoustic pulse, which propogates through the water and sediment columns. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), and detected at the hydro- phone. This process is repeated at intervals ranging between 250 milliseconds and 10 seconds depending on the source type. In this way a two-dimensional image of the geologic structure beneath the ship track is constructed. Seismic data are stored in SEG-Y format, which is a standard digital format that can be read and manipulated by most seismic-processing software packages. The SEG-Y file format includes a 3200-byte descriptive header that should contain detailed information regarding the data acquisition and processing parameters. The navigation data are stored in flat ASCII files as latitude and longitude values that can be used to plot track maps of the seismic profiles at any scale or map projection desired. The data and format of the navigation files are described in the file prologue.
  1. How might this data set be cited?
    U.S. Geological Survey, Coastal and Marine Geology Team(ed.), and Region, Western, Unknown, Marine Seismic Reflection Profiles Data of San Francisco Bay Area.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.29
    East_Bounding_Coordinate: -122.23
    North_Bounding_Coordinate: +37.69
    South_Bounding_Coordinate: +37.61
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 05-Oct-1999
    Publication Date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: remote-sensing image
  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?
  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
    • Coastal and Marine Geology Team(ed.)
    • Western Region
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Jonathan R. Childs
    U.S. Geological Survey
    U.S. Geological Survey Mail Stop 999 345 Middlefield Rd.
    Menlo Park, CA

    650-329-5195 (voice)

Why was the data set created?

Marine seismic reflection data are used to image and map sedimentary and structural features of the seafloor and subsurface. These data are useful in mapping faults (such as the San Andreas and Hayward Faults) where they pass under the waters of the San Francisco Bay, and in assessing other submarine geologic characteristics and features.

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: 24-Jan-2017 (process 1 of 1)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
  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?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  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
U.S. Geological Survey requests to be acknowledged as the data collector in any publication or other use of these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    Clint Steele
    U.S. Geological Survey Mail Stop 999 345 Middlefield Rd.
    Menlo Park, CA

    650-329-5055 (voice)
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 24-Jan-2017
Metadata author:
Clint Steele
U.S. Geological Survey Mail Stop 999 345 Middlefield Rd.
Menlo Park, CA

650-329-5055 (voice)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (June 8, 1994)

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