Multichannel sparker seismic-reflection data of field activity 2016-656-FA; between Icy Point and Dixon Entrance, Gulf of Alaska from 2016-08-07 to 2016-08-26

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Frequently anticipated questions:


What does this data set describe?

Title:
Multichannel sparker seismic-reflection data of field activity 2016-656-FA; between Icy Point and Dixon Entrance, Gulf of Alaska from 2016-08-07 to 2016-08-26
Abstract:
This data release contains high-resolution multichannel seismic (MCS) reflection data collected in August of 2016 along the southeast Alaska continental margin. Structure perpendicular MCS profiles were collected along the Queen Charlotte-Fairweather fault. The data were collected aboard the R/V Norseman using a Delta sparker sound source and recorded on a 64-channel digital streamer. Subbottom acoustic penetration spans up to several hundreds of meters, and is variable by location.
Supplemental_Information:
Additional information about the field activities from which these data were derived is available online at: https://cmdgs.marine.usgs.gov/fan_info.php?fan=2016-656-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?
    Balster-Gee, Alicia F., Brothers, Daniel S., Miller, Nathaniel C., Kluesner, Jared W., Ebuna, Daniel R., and East, Amy E., 2017, Multichannel sparker seismic-reflection data of field activity 2016-656-FA; between Icy Point and Dixon Entrance, Gulf of Alaska from 2016-08-07 to 2016-08-26: data release DOI:10.5066/F7KP81BQ, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -147.794
    East_Bounding_Coordinate: -133.78027201
    North_Bounding_Coordinate: 60.73911751
    South_Bounding_Coordinate: 54.63955538
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5a0201c1e4b0531197b72d36?name=2016-656-FA_Index_map.jpg&allowOpen=true (JPEG)
    index map
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 07-Aug-2106
    Ending_Date: 26-Aug-2016
    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 the standard header locations.
    2. What coordinate system is used to represent geographic features?
      The map projection used is WGS 1984 UTM Zone 8N.
      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)
    • Alicia F. Balster-Gee
    • Daniel S. Brothers
    • Nathaniel C. Miller
    • Jared W. Kluesner
    • Daniel R. Ebuna
    • Amy E. East
  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?

The U.S. Geological Survey (USGS) collected high-resolution seismic-reflection profiles in August 2016 in the Gulf of Alaska, between Icy Point and Dixon Entrance. The survey was designed to map the Queen Charlotte-Fairweather Fault zone that extends along the southeast Alaska continental margin. This work was funded by the USGS Coastal and Marine Geology Program‚ Marine Geohazards Project. These high-resolution seismic-reflection profiles image the shallow structure and stratigraphy along the Queen Charlotte-Fairweather Fault system. This data can be used to better understand its deformation history and the interplay between Quaternary deformation and sedimentary processes. This geologic information is essential to hazard assessment and coastal and marine spatial planning at Federal, State and local levels, as well as to future research on the geomorphic, sedimentary, tectonic and climatic record of southeastern Alaska.

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: 26-Aug-2016 (process 1 of 4)
    Seismic-reflection data were collected using a sparker system that creates an acoustic signal by discharging a high-voltage electrical pulse between electrodes and a ground that generates a frequency spectrum. Data were acquired using a 64-channel (6.25 m group spacing) Geometrics GeoEel digital hydrophone streamer and recorded in SEG-Y 32-bit floating point.
    Date: 01-Oct-2017 (process 2 of 4)
    Seismic-reflection data were processed using Echos by Paradigm Geophysical. The following processing steps were applied to each line: AGC applied over 1000ms gate, normal moveout correction (constant 1550 m/s velocity), stack, and correct navigation was written to header bytes 181 and 185. Data sources used in this process:
    • brute stack
    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: 13-Oct-2021 (process 4 of 4)
    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.
  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 2016-656-FA using a 64-channel (1.56 and 3.25 m group spacing) Geometrics GeoEel digital hydrophone streamer, 2.4 kJ Applied Acoustics power supply and Delta Sparker sound source. 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. 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? Zip files contain high-resolution seismic-reflection (SEG-Y) data collected during PCMSC field activity 2016-656-FA. The data are divided up and presented by navigation line(s), as reflected in the individual zip 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?
  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:
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)

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