Minisparker seismic-reflection data collected between Point Sur and Morro Bay, offshore of central California, from 2011-09-12 to 2011-09-26 (USGS field activity B-05-11-CC)

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Frequently anticipated questions:


What does this data set describe?

Title:
Minisparker seismic-reflection data collected between Point Sur and Morro Bay, offshore of central California, from 2011-09-12 to 2011-09-26 (USGS field activity B-05-11-CC)
Abstract:
This dataset includes raw, and swell-filtered, high-resolution seismic-reflection data, collected by the U.S. Geological Survey (USGS) in 2011, between Point Sur and Morro Bay in central California.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=B0511CC . 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?
    Johnson, Samuel Y., Hartwell, Stephen R., Sliter, Ray W., and Beeson, Jeffrey W., 2017, Minisparker seismic-reflection data collected between Point Sur and Morro Bay, offshore of central California, from 2011-09-12 to 2011-09-26 (USGS field activity B-05-11-CC): data release DOI:10.5066/F7K35S44, U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.05559
    East_Bounding_Coordinate: -120.86195
    North_Bounding_Coordinate: 36.95890
    South_Bounding_Coordinate: 35.29984
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 12-Sep-2011
    Ending_Date: 26-Sep-2011
    Currentness_Reference:
    ground condition at the time the data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: minisparker 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 provided in ASCII position files and are stored in the SEG-Y data trace headers in the standard header locations.
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_84.
      The ellipsoid used is WGS_84.
      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:
    Navigation and 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)
    • Samuel Y. Johnson
    • Stephen R. Hartwell
    • Ray W. Sliter
    • Jeffrey W. Beeson
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    PCMSC Science Data Coordinator
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

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

Why was the data set created?

This data release includes marine geophysical data collected on cruise B-05-11-CC between Point Sur and Morro Bay, California. The overall goal of this research is to understand the shallow geologic framework of this area as a contribution to the California Seafloor Mapping Program (Johnson and others, 2017). Particular focus is on mapping active faults and documenting the distribution and thickness of offshore, unconsolidated sediment. Approximately 700 km of single-channel, seismic-reflection data between Point Sur and Morro Bay were collected during the cruise. Seismic profiles were collected at 1 km line spacing between Point Sur and Piedras Blancas, crossing the Hosgri-San Gregorio fault system 60 times. Data were also collected to the south on the south flank of Piedras Blancas (south of San Simeon) crossing the Hosgri-San Gregorio fault 13 times at 800 m line spacing. Farther south, additional data were collected offshore of Morro Bay with a focus on crossing the Los Osos fault zone. Data collected in the southern two areas overlap with and supplement data available in Sliter and others (2009). Seismic-reflection data were collected using a minisparker system that creates an acoustic signal by discharging an electrical pulse between electrodes and a ground that generates a frequency spectrum roughly between 200 and 1600 Hz. At boat speeds of 4 to 4.5 nm/hour, seismic traces were collected roughly every 1 to 2 meters. Water depths were between 20 m and 600 m. Acoustic pulses were generated at 0.5-second intervals on profiles where maximum depth was about 300 m; a 1-second interval was used on the deeper water profiles. Standard SEG-Y files were generated using a Triton Subbottom Logger (SBL). Seismic data processing was accomplished using Sioseis, a public-domain software developed at Scripps Institute of Oceanography (part of the University of California at San Diego), and SeismicUnix developed at the Colorado School of Mines. The processing of these data consisted of a bandpass filter, mute function, automatic gain control, water bottom detect, swell correction, and scaling/plotting. Both raw data in SEG-Y format and processed (corrected) data are provided here.

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: 2011 (process 1 of 4)
    Seismic-reflection data were collected using a minisparker system that creates an acoustic signal by discharging a 500-Joule, high-voltage electrical pulse between electrodes and a ground that generates a frequency spectrum roughly between 200 and 1,600 Hz. At boat speeds of 4 to 4.5 nm/hour, seismic traces were collected roughly every 1 to 2 meters. The data were recorded on a 15-m-long hydrophone streamer in standard SEG-Y 32-bit floating-point format with Triton Subbottom Logger (SBL) software that merges seismic-reflection data with differential GPS navigation data.
    Date: 2011 (process 2 of 4)
    Seismic-reflection SEG-Y files were corrected for swell effects using Sioseis software (see: http://sioseis.ucsd.edu/procs.html). SEG-Y header data were normalized using the "header" Sioseis processes, and a band pass filter was applied. Next, each SEG-Y file was displayed using Seisee (available at http://www.dmng.ru/en/freeware.html) and up to 16 water-bottom time/shot-point pairs where recorded to guide the automated water-bottom picker used to mute the water column. Finally, a swell filter was applied to the data, and the results were exported as a new SEG-Y file.
    The following parameters were used for each step in the process:
    
    header: fno 0 lno 9999999 ftr 0 ltr 99999 l4 = l3
    
    header2: fno 0 lno 99999 ftr 0 ltr 99999 r59 = r50
    
    filter: ftype 0 pass 160 1600
    
    water bottom picker: solrat between 2-5 ses 0  0.002 sel 0  0.5
    
    swell: n 35
    
    Date: 19-Oct-2020 (process 3 of 4)
    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
    Date: 31-Aug-2021 (process 4 of 4)
    Data were moved to a new repository, and metadata was edited to reflect the new location. Other edits were performed as needed to bring the metadata up to PCMSC standards, including a slight rewording of the title. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Johnson, Samuel Y., Cochrane, Guy R., Golden, Nadine E., Hartwell, Stephen R., Cochran, Susan A., and Watt, Janet T., 2017, The California Seafloor Mapping Program - Providing science and geospatial data for California's State Waters: Ocean and Coastal Management v.140, p. 88-104, Elsevier, Atlanta, GA.

    Online Links:

    Sliter, Ray W., Triezenberg, Peter J., Hart, Patrick E., Watt, Janet T., Johnson, Samual Y., and Scheirer, Daniel S., 2009, High-resolution seismic reflection and marine magnetic data along the Hosgri Fault Zone, central California: Open-File Report 2009-1100, U.S. Geological Survey, Reston, VA.

    Online Links:


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 Differential Global Positioning System (DGPS) navigation receiver. The SIG 2mille hydrophone streamer and sparker electrodes were deployed 20m behind the DGPS receiver. Layback is estimated to be 20 plus or minus 5m. No layback correction from the DGPS receiver position was applied to navigation data.
  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. Vertical resolution is approximately 1 millisecond and vertical accuracy is approximately plus or minus 4 milliseconds depending on sea state.
  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 B-05-11-CC using a SIG 2mille minisparker system consisting of a hydrophone streamer, high-voltage power supply and discharge sparker tips. 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(s) of the dataset and in products derived from these data. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This information is not intended for navigational purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - CMGDS
    2885 Mission Street
    Santa Cruz, CA
    USA

    1-831-427-4747 (voice)
  2. What's the catalog number I need to order this data set? B-05-11-CC.scs.sparker.zip – this zip file contains raw and swell-corrected high-resolution seismic-reflection (SEG-Y) and navigation (ASCII) data collected during PCMSC field activity B-05-11-CC. The data are divided up and presented by navigation line, as reflected in the individual file name(s).
  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?
    • Availability in digital form:
      Data format: Zip file contains the raw and swell-corrected seismic data per navigation line in format SEG-Y (version SEG-Y rev 1) Size: 19196
      Network links: https://doi.org/10.5066/F7K35S44
    • Cost to order the data: None


Who wrote the metadata?

Dates:
Last modified: 10-Sep-2021
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission St.
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/CMGDS_DR_tool/DR_F7K35S44/B-05-11-CC.scs.sparker_metadata.faq.html>
Generated by mp version 2.9.50 on Thu Oct 21 09:29:12 2021