Chirp seismic-reflection data from field activity L-1-06-SF collected offshore Bolinas to San Francisco, California on 2006-09-30

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:
Chirp seismic-reflection data from field activity L-1-06-SF collected offshore Bolinas to San Francisco, California on 2006-09-30
Abstract:
High-resolution Chirp seismic-reflection data were collected by the U.S. Geological Survey in September 2006 offshore San Francisco, California. Data were collected aboard the R/V Lakota, during field activity L-1-06-SF. Chirp data were collected using an EdgeTech 512 chirp subbottom profiler and recorded with a Triton SB-Logger.
Supplemental_Information:
Additional information about the field activities from which these data were derived is available online at:
http://cmgds.marine.usgs.gov/fan_info.php?fan=L106SF
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Ryan, Holly F., Sliter, Ray W., and Hart, Patrick E., 20191127, Chirp seismic-reflection data from field activity L-1-06-SF collected offshore Bolinas to San Francisco, California on 2006-09-30: data release DOI:10.5066/P9XDFD92, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Ryan, Holly F., Sliter, Ray W., and Hart, Patrick E., 2019, Chirp and minisparker seismic-reflection data of field activity L-1-06-SF collected offshore Bolinas to San Francisco, California, from 2006-09-25 to 2006-10-03: data release DOI:10.5066/P9XDFD92, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.48652
    East_Bounding_Coordinate: -122.48624
    North_Bounding_Coordinate: 37.81508
    South_Bounding_Coordinate: 37.75838
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5cf804c0e4b07f02a7046551?name= L106SF_Chirp_nav.jpg&allowOpen=true (JPEG)
    Image showing chirp tracklines
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 30-Sep-2006
    Ending_Date: 30-Sep-2006
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: seismic-reflection data in SEG-Y format
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Horizontal X and Y locations for the seismic profile locations are stored in the SEG-Y data trace headers in header bytes 81 and 85.
    2. What coordinate system is used to represent geographic features?
      The map projection used is WGS 1984 UTM Zone 10N.
      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0001
      Ordinates (y-coordinates) are specified to the nearest 0.0001
      Planar coordinates are specified in Meter
      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview: Seismic Shots with Time Stamp in standard SEG-Y file format
    Entity_and_Attribute_Detail_Citation:
    Society of Exploration Geophysicists (SEG) Technical Standards, available for download at http://seg.org/Publications/SEG-Technical-Standards

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Holly F. Ryan
    • Ray W. Sliter
    • Patrick E. Hart
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

This work was funded by the USGS Coastal and Marine Geology Program’s Marine Geohazards project. The high-resolution seismic-reflection profiles provide fault geometry information of the San Gregorio, San Andreas, and Golden Gate faults to be used to update the USGS Quaternary fault database and in shaking hazard models developed by the Working Group for California Earthquake probabilities. Other objectives of the mission were to determine thickness of Holocene sediments and verify surficial mapping based on multibeam with surficial features and sediment cover based on subbottom systems. These data and information are intended for science researchers, students from elementary through college, policy makers, and general public.

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: 30-Sep-2006 (process 1 of 3)
    Chirp seismic-reflection data were collected using an Edgetech 512 Chirp subbottom profiling system consisting of a source transducer and an array of receiving hydrophones housed in a 500-lb “fish” towed at a depth of several meters below the sea surface. The swept-frequency “chirp” source signal is between 500 and 4,500 Hz, and the data are recorded by hydrophones located on the bottom of the fish and recorded in SEG-Y 32-bit floating point using a Triton SB-Logger. 15 lines were collected and line “01” was used as a test line and was not recorded. GPS position information was inserted into the SEG-Y trace headers in header bytes 73 and 77, with a scalar of -1000 (noted in header byte 71).
    Date: 20-Jul-2019 (process 2 of 3)
    Chirp seismic-reflection SEG-Y files consist of the internally transformed amplitude envelope channel corrected for the depth of the fish below the sea surface using Paradigm Geophysical Echos seismic processing software. 1) SEG-Y channel with sequence number “1” was written to a SEG-Y file; 2) The fish depth header word (byte location 49 in SEG-Y file) was read and converted from millimeters to two-way travel time to create a fish-depth static value; and 3) The fish depth static was applied to the data to correct for the vertical up and down movement of the Chirp fish. UTM 10N x and y position data were inserted into SEG-Y header bytes 81 and 85. Additionally, ship-heave statics were calculated using SIOSEIS seismic processing. The statics were created with a seafloor auto-tracker to detect the seafloor two-way travel time for each shot. This tracker defaults to the time value of the previous shot on low amplitude traces. Corrections were applied to the data to filter out the effect of the sea swell. A seafloor mute was applied before the final processed lines were output in SEG-Y format.
    Date: 19-Oct-2020 (process 3 of 3)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@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?
    Identified as best available version
  2. How accurate are the geographic locations?
    Position data were provided by a Hemisphere V100 Global Positioning System using L1, C/A code and carrier phase smoothing with a stated accuracy of 60 centimeters.
  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?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    Subbottom data were collected during USGS cruise L-1-06-SF using an Edgetech 512 Chirp subbottom profiling system. Quality control was conducted during the collection process.

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:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in SEG-Y format in a single zip file (L106SF_Chirp_segy.zip).
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    Use of SEG-Y data requires specialized software, such as ProMax and Seisworks by Landmark Geophysical; FOCUS and SeisX by Paradigm Geophysical; SPW by Parallel Geoscience; VISTA by Seismic Image Software; SeiSee by Dalmorneftegeophysica (DMNG); amongst others.

Who wrote the metadata?

Dates:
Last modified: 19-Oct-2020
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P9XDFD92/L106SF_Chirp_segy_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:17:34 2021