Multichannel minisparker seismic-reflection data of field activity 2015-651-FA; Chatham Strait and Cross Sound, southeastern Alaska from 2015-08-03 to 2015-08-21

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Frequently anticipated questions:


What does this data set describe?

Title:
Multichannel minisparker seismic-reflection data of field activity 2015-651-FA; Chatham Strait and Cross Sound, southeastern Alaska from 2015-08-03 to 2015-08-21
Abstract:
This data release contains high-resolution multichannel seismic (MCS) reflection data collected in August of 2015 to explore marine geologic hazards of inland waterways of southeastern Alaska. Sub-bottom profiles were acquired in the inland waters between Glacier Bay and Juneau, including Cross Sound and Chatham Strait. High-resolution seismic-reflection profiles were acquired to assess evidence for active seabed faulting and submarine landslide hazards. The data were collected aboard the US Geological Survey R/V Alaskan Gyre. The seismic-reflection data were acquired using a 500-Joule minisparker source and a 48-channel Geometrics GeoEel digital streamer. Subbottom acoustic penetration spans up to several hundreds of meters, and is variable by location. This data release contains CMP sorted digital data in SEG-Y format. This data release will be updated as subsequent lines of data from this field activity are published.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at: http://compass.er.usgs.gov/fan_info.php?fan=2015-651-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., Conrad, James R., Kluesner, Jared W., Hart, Patrick E., and Haeussler, Peter J., 2017, Multichannel minisparker seismic-reflection data of field activity 2015-651-FA; Chatham Strait and Cross Sound, southeastern Alaska from 2015-08-03 to 2015-08-21: data release DOI:10.5066/F7RX9B1R, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    This is part of the following larger work.

    Balster-Gee, Alicia F., Brothers, Daniel S., Conrad, James R., Kluesner, Jared W., Hart, Patrick E., and Haeussler, Peter J., 2017, Multichannel minisparker and chirp seismic-reflection data of field activity 2015-651-FA; Chatham Strait and Cross Sound, southeastern Alaska from 2015-08-03 to 2015-08-21: data release DOI:10.5066/F7RX9B1R, 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: -153.457
    East_Bounding_Coordinate: -133.404
    North_Bounding_Coordinate: 58.4340
    South_Bounding_Coordinate: 52.2441
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/59e786f3e4b05fe04cd3a249?name=2015-651-FA_mcs_index_map.jpg&allowOpen=true (JPEG)
    index map
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 03-Aug-2015
    Ending_Date: 21-Aug-2015
    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:
    multichannel 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)
    • Alicia F. Balster-Gee
    • Daniel S. Brothers
    • James R. Conrad
    • Jared W. Kluesner
    • Patrick E. Hart
    • Peter J. Haeussler
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Alicia F. Balster-Gee
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Geophysicist
    2885 Mission Street
    Santa Cruz, CA
    USA

    831-460-7581 (voice)
    831-427-4748 (FAX)
    abalster-gee@usgs.gov

Why was the data set created?

The U.S. Geological Survey (USGS) collected high-resolution multichannel seismic-reflection data in August of 2015, in the inland waterways between Glacier bay and Juneau including Chatham Strait and Cross Sound, in southeastern Alaska. The survey was designed to identify the spatial distribution of active faults, assess the regional evidence for active seabed faulting, and identify submarine landslide hazards. These data can be used to better image and understand the deformation history and earthquake/tsunami hazards of the Queen Charlotte-Fairweather fault system, a major plate boundary strike-slip fault system that accommodates more than ninety percent of the relative motion between the Pacific and North American plates. In addition, the survey images submarine landslides in these inland waterways of southeastern Alaska in order to determine causes and age of seafloor failure. This work was funded by the USGS Coastal and Marine Geology Program’s Marine Geohazards Project and the Alaska Department of Fish and Game (ADFG). The high-resolution seismic-reflection profiles of bedrock, sediment deposits and tectonic structure provide geologic information that is essential to hazard assessment, regional sediment management 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: 2015 (process 1 of 1)
    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 400 and 1,000 Hz. Data were acquired using a 48-channel (6.25 m group spacing) Geometrics GeoEel digital hydrophone streamer and recorded in SEG-Y 32-bit floating point.
  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 2015-651-FA using 48-channel (6.25 m group spacing) Geometrics GeoEel digital hydrophone streamer, 500 Joule Applied Acoustics power supply and SIG minisparker 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. 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 - 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? high-resolution seismic-reflection (SEG-Y) data collected during PCMSC field activity 2015-651-FA. The data are divided up and zipped together 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?

Who wrote the metadata?

Dates:
Last modified: 19-Oct-2017
Metadata author:
Alicia F. Balster-Gee
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Geophysicist
2885 Mission Street
Santa Cruz, CA
USA

831-460-7581 (voice)
831-427-4748 (FAX)
abalster-gee@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/2015-651-FA__mcs_metadata.faq.html>
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