Marine Seismic Reflection Profiles Data of San Francisco Bay Area

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Frequently anticipated questions:


What does this data set describe?

Title:
Marine Seismic Reflection Profiles Data of San Francisco Bay Area
Abstract:
Dataset consists of two-dimensional marine seismic reflection profile data from the San Francisco Bay area. These data were acquired in 1995, with the vessel Robert Gray. The USGS identifier for these data is G295SF.
For more information on the seismic surveys see http://walrus.wr.usgs.gov/infobank/g/g295sf/html/g-2-95-sf.meta.html
These data are also available via GeoMapApp (http://www.geomapapp.org/) and Virtual Ocean ( http://www.virtualocean.org/) earth science exploration and visualization applications.
Supplemental_Information:
Seismic reflection profiles are acquired by means of anacoustic source (usually generated electromagneticallyor with compressed air), and a hydrophone or hydrophonearray. Both elements are typically towed in the waterbehind a survey vessel. The sound source emits a shortacoustic pulse, which propogates through the water andsediment columns. The acoustic energy is reflected atdensity boundaries (such as the seafloor or sedimentlayers beneath the seafloor), and detected at the hydro-phone. This process is repeated at intervals rangingbetween 250 milliseconds and 10 seconds dependingon the source type. In this way a two-dimensional imageof the geologic structure beneath the ship track isconstructed.Seismic data are stored in SEG-Y format, which is astandard digital format that can be read and manipulatedby most seismic-processing software packages. TheSEG-Y file format includes a 3200-byte descriptive headerthat should contain detailed information regarding thedata acquisition and processing parameters.The navigation data are stored in flat ASCII files aslatitude and longitude values that can be used to plottrack maps of the seismic profiles at any scale or mapprojection desired. The data and format of the navigationfiles 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: -122.77
    East_Bounding_Coordinate: -121.68
    North_Bounding_Coordinate: +38.16
    South_Bounding_Coordinate: +37.49
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 05-Oct-1999
    Currentness_Reference:
    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
    geophysicist
    U.S. Geological SurveyMail Stop 999345 Middlefield Rd.
    Menlo Park, CA

    650-329-5195 (voice)
    jchilds@usgs.gov

Why was the data set created?

Marine seismic reflection data are used to image andmap sedimentary and structural features of the seafloorand subsurface. These data are useful in mappingfaults (such as the San Andreas and Hayward Faults)where they pass under the waters of the San FranciscoBay, and in assessing other submarine geologiccharacteristics 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)
    aallwardt@usgs.gov
  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
Use_Constraints:
U.S. Geological Survey requests to be acknowledgedas the data collector in any publication or other use ofthese data.
  1. Who distributes the data set? (Distributor 1 of 1)
    Jonathan R. Childs
    U.S. Geological Survey
    geophysicist
    Mail Stop 999 345 Middlefield Rd.
    Menlo Park, CA

    650-329-5195 (voice)
    jchilds@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable SEGY data
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 24-Jan-2017
Metadata author:
Clint Steele
U.S. Geological SurveyMail Stop 999345 Middlefield Rd.
Menlo Park, CA

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

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/54.faq.html>
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