Multichannel sparker seismic-reflection data between Cross Sound and Dixon Entrance, offshore southeastern Alaska, collected from 2016-05-17 to 2016-06-12 during field activity 2016-625-FA

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Frequently anticipated questions:


What does this data set describe?

Title:
Multichannel sparker seismic-reflection data between Cross Sound and Dixon Entrance, offshore southeastern Alaska, collected from 2016-05-17 to 2016-06-12 during field activity 2016-625-FA
Abstract:
Multichannel sparker (MCS) seismic-reflection data were collected along the Queen Charlotte-Fairweather Fault between Cross Sound and Dixon Entrance, offshore southeastern Alaska from 2016-05-17 to 2016-06-12. Data were collected aboard the Alaska Department of Fish and Game R/V Medeia, and recorded using a 32 channel GeoEel digital streamer, an Applied Acoustics power supply, and a SIG SLP 790 Sparker Electrode. MCS profiles were collected coincident with multibeam data collected at higher survey speeds (5-6 knots), which reduced the MCS data quality.
Supplemental_Information:
Additional information about the field activities from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2016-625-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., Andrews, Brian D., Brothers, Daniel S., Uri S. ten Brink, Kluesner, Jared W., Haeussler, Peter J., and Hart, Patrick E., 2017, Multichannel sparker seismic-reflection data between Cross Sound and Dixon Entrance, offshore southeastern Alaska, collected from 2016-05-17 to 2016-06-12 during field activity 2016-625-FA: data release DOI:10.5066/F7NG4PTW, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Balster-Gee, Alicia F., Brothers, Daniel S., Andrews, Brian D., Uri S. ten Brink, Kluesner, Jared W., and Haeussler, Peter J., 2017, Multibeam bathymetry and backscatter data and multichannel sparker seismic-reflection data between Cross Sound and Dixon Entrance, offshore southeastern Alaska, collected from 2016-05-17 to 2016-06-12 during field activity 2016-625-FA: data release DOI:10.5066/F7NG4PTW, 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: -136.913215
    East_Bounding_Coordinate: -134.338608
    North_Bounding_Coordinate: 58.023711
    South_Bounding_Coordinate: 55.031169
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5a0a218be4b09af898c9ef07?name=2016-625-FA_index_map.jpg&allowOpen=true (JPEG)
    Thumbnail image of bathymetric terrain model of Queen Charlotte Fault area with MCS lines shown in black, southeastern Gulf of Alaska.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 17-May-2016
    Ending_Date: 12-Jun-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 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 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
    • Brian D. Andrews
    • Daniel S. Brothers
    • Uri S. ten Brink
    • Jared W. Kluesner
    • Peter J. Haeussler
    • Patrick E. Hart
  2. Who also contributed to the data set?
    Data was collected aboard Alaska Department of Fish and Game’s R/V Medeia and would not be possible without the support of vessel crew members Jim deLaBruere, Craig Conger, Cedar Stark, and Becky Wilson.
  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?

The Queen Charlotte-Fairweather Fault (QCFF) is a major structural feature that extends more than 1,200 km from northern Vancouver Island, Canada to the Fairweather Range of southern Alaska. The fault system represents a major transform boundary that separates the Pacific Plate from the North American Plate, and in many ways, can be considered an analog “sister” fault to California’s San Andreas Fault. Early studies in the 1970s and 1980s based on historical marine geophysical data demonstrated that approximately 75 percent of the system is located offshore along the continental shelf-edge and slope, more than 20-50 km from land in eastern Gulf of Alaska. Historical seismicity records dating back to 1890 include dozens of large magnitude earthquakes, including eight events of magnitude greater than 7 and Canada’s largest earthquake on record (1949, M8.1). Finally, two recent earthquakes, a M7.8 in 2012 (“Haida Gwaii earthquake”) and M7.5 in 2013 (“Craig earthquake”) stimulated a substantial amount of scientific study of the QCFF and renewed concern over potential threats to coastal infrastructure and populations residing in southeastern Alaska and northwestern British Columbia. Survey goals included determining how fast the two sides of the fault move past each other (slip rate) and deciphering the historical movement of the fault. We also want to better understand how large earthquakes might trigger potentially dangerous underwater landslides. The purpose of this data is to provide seismic-reflection profiles primarily oriented along strike of the Queen Charlotte Fault and adjacent seafloor.

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: 10-Dec-2016 (process 1 of 4)
    Seismic-reflection data were processed using Echos by Paradigm Geophysical. The following processing steps were applied to each line: flipped reversed channels, kill bad traces during shutdowns, applied velocities hanging from seafloor, 80-600 bandpass filter, spherical divergence gain, AGC applied over a 1000ms gate, normal moveout correction (constant 1480m/s velocity), swell correction statics, three trace mean runmix filter, 80-600 butterworth filter, water column mute, two pass prestack spiking deconvolution, stack, post-stack predictive deconvolution, 80-600 post-stack bandpass filter, post-stack AGC, post-stack three trace mean runmix filter, time migration, post-migration 3 trace runmix filter, and correct navigation written to header bytes 81 and 85. Data sources used in this process:
    • processing
    Date: 07-Mar-2019 (process 2 of 4)
    Corrected typo in Ending Date in Time Period of Content section. Changed both Point of Contact and Metadata Contact information to new PCMSC static contact information. Person who carried out this activity:
    Susan A Cochran
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission St.
    Santa Cruz, CA
    United States

    831-460-7545 (voice)
    scochran@usgs.gov
    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 with +/- 10 centimeter accuracy.
  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?
    Subbottom data were collected during USGS cruise 2016-625-FA using a 32-channel (3.125 meter group spacing) Geometrics GeoEel digital hydrophone streamer, Applied Acoustics power supply, and SIG SLP 790 Sparker Electrode. 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? Zip file FA-625-2016_sgy.zip contains processed high-resolution seismic-reflection (SEG-Y) data collected during PCMSC field activity 2016-625-FA. 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?
  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/ScienceBase/DR_F7NG4PTW/2016-625-FA_MCS_Metadata.faq.html>
Generated by mp version 2.9.50 on Thu Oct 14 14:47:21 2021