High-resolution Chirp seismic-reflection data from USGS cruise 2018-641-FA, collected in south-central California in support of the Bureau of Ocean Energy Management (BOEM)-funded California Deepwater Investigations and Groundtruthing (Cal DIG I) offshore alternative energy project from 2018-08-29 to 2018-09-20

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Frequently anticipated questions:


What does this data set describe?

Title:
High-resolution Chirp seismic-reflection data from USGS cruise 2018-641-FA, collected in south-central California in support of the Bureau of Ocean Energy Management (BOEM)-funded California Deepwater Investigations and Groundtruthing (Cal DIG I) offshore alternative energy project from 2018-08-29 to 2018-09-20
Abstract:
High-resolution Chirp seismic-reflection data were collected offshore south-central California as part of a geophysical survey aboard the NOAA Ship Rainier during two legs at sea, the first from 8/28/2018 to 9/7/2018 and the second from 9/10/2018 to 9/21/2018. The data were collected using an Edgetech 512i towfish with a 1-6 kHz sweep. Consistently high winds and rough seas prevented additional Chirp data collection and caused noisy data in some cases, especially during the second leg of the survey, which largely took place in the southern part of the study area. The Chirp data were post-processed to include filtering and other noise removal corrections.
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=2018-641-FA
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?
    Kennedy, Daniel J., Walton, Maureen A.L., Cochrane, Guy R., Balster-Gee, Alicia F., Kluesner, Jared W., Hart, Patrick E., Sliter, Ray W., Miller, Jennifer K., and Gilbane, Lisa, 20210711, High-resolution Chirp seismic-reflection data from USGS cruise 2018-641-FA, collected in south-central California in support of the Bureau of Ocean Energy Management (BOEM)-funded California Deepwater Investigations and Groundtruthing (Cal DIG I) offshore alternative energy project from 2018-08-29 to 2018-09-20: data release DOI:10.5066/P9JU17GE, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Kennedy, Daniel J., Walton, Maureen A.L., Cochrane, Guy R., Balster-Gee, Alicia F., Kluesner, Jared W., Hart, Patrick E., Sliter, Ray W., Miller, Jennifer K., and Gilbane, Lisa, 2021, High-resolution multi-channel and Chirp seismic-reflection data from USGS cruise 2018-641-FA, collected in south-central California in support of the Bureau of Ocean Energy Management (BOEM)-funded California Deepwater Investigations and Groundtruthing (Cal DIG I) offshore alternative energy project from 2018-08-29 to 2018-09-20: data release DOI:10.5066/P9JU17GE, 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: -121.98
    East_Bounding_Coordinate: -120.94
    North_Bounding_Coordinate: 35.83
    South_Bounding_Coordinate: 34.53
  3. What does it look like?
    Cal_DIG_I_Chirp_tracklines.png (PNG)
    Thumbnail image of bathymetric terrain model of the Cal DIG I project area with chirp lines shown in red, south-central California.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 29-Aug-2018
    Ending_Date: 20-Sep-2018
    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 provided in ASCII position files and are stored in the SEG-Y data trace headers in header bytes 181 and 185 locations.
    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:
    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)
    • Daniel J. Kennedy
    • Maureen A.L. Walton
    • Guy R. Cochrane
    • Alicia F. Balster-Gee
    • Jared W. Kluesner
    • Patrick E. Hart
    • Ray W. Sliter
    • Jennifer K. Miller
    • Lisa Gilbane
  2. Who also contributed to the data set?
    Data were collected aboard NOAA’s (National Oceanic and Atmospheric Administration) Rainier research vessel, funded by the Buereau of Ocean Energy Management (BOEM) in order to adequately address potential impacts in environmental impact statements and environmental assessments under the National Environmental Policy Act (NEPA).
  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
    USA

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

Why was the data set created?

These data were collected as part of the California Deepwater Investigations and Groundtruthing (Cal DIG I) project, which focuses on the offshore south-central region of California at water depths of 500 to 1,200 meters, in Federal waters outside of the State of California three nautical mile limit. The goal of study is to conduct a reconnaissance survey of the outer continental shelf of south-central California for the purpose of improving regional models of seafloor (benthic) habitats, geologic hazards, and sedimentary processes. Geophysical and geological data from this project are needed to address important issues associated with marine spatial planning, ecosystem assessments, geohazards, and offshore infrastructure.

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: 08-Oct-2019 (process 1 of 2)
    Chirp Subbottom data were collected during USGS cruise 2018-641-FA using an Edgetech 5 12i Chirp towfish deployed from the NOAA ship Rainier’s main A-frame and operated at a 1-6 kHz sweep. The data were collected along sub-perpendicular dip lines across previously surveyed areas in water depths up to ~1,200 m, generating imagery as much as 30-50 m into the subsurface. Upon collection, the Chirp data were first converted from native .jsf format to .segy envelope format and were then transferred to a file server to be processed with Echos paradigm software. The water column was cropped to enable processing at a shorter record length, and a water-bottom mute was also applied to remove sparker cross-talk noise in the water column. Towfish depth and swell corrections were applied, and the data were median-filtered and trace-balanced where necessary to correct for amplitude variations introduced by sparker cross-talk and the Edgetech software auto-gain during acquisition. Where marine wildlife shutdowns occurred, missing traces were filled by blank traces. Lastly, data were spliced together and renamed to match their corresponding Multi-channel seismic (MCS) lines collected during the same survey.
    Date: 13-Oct-2021 (process 2 of 2)
    Performed minor edits to the metadata to correct typos. 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?

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 with a stated accuracy of +/- 10 centimeter.
  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 accuracy ranges between +/- 0.2 and 1 meter.
  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?
    No formal logical accuracy tests were conducted.

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)
    PCMSC Science Data Coordinator
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA
    USA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov
  2. What's the catalog number I need to order this data set? This part of the data release contains processed, high-resolution Chirp seismic-reflection (SEG-Y) data collected during PCMSC field activity 2018-641-FA. The data are divided up and presented by navigation line, as reflected in the individual file name(s). File sizes range from 4.1 MB to 805.8 MB.
  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: Processed, high-resolution Chirp seismic-reflection data per navigation line. File sizes range from 4.1 MB to 805.8 MB. in format SEG-Y (version SEGY rev 1) Size: 805.8
      Network links: https://doi.org/10.5066/P9JU17GE
    • Cost to order the data: None.

  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: 13-Oct-2021
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA
USA

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_P9JU17GE/CalDIG_2018-641-FA_CHIRP_Metadata.faq.html>
Generated by mp version 2.9.50 on Thu Oct 14 14:47:20 2021