Seismic Reflection, EdgeTech SB-424 Chirp shot points collected in the vicinity of Buffalo Reef, Michigan, within Lake Superior during USGS field activity 2018-043-FA, (CSV text and Esri point shapefile, GCS WGS 84)

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Frequently anticipated questions:


What does this data set describe?

Title:
Seismic Reflection, EdgeTech SB-424 Chirp shot points collected in the vicinity of Buffalo Reef, Michigan, within Lake Superior during USGS field activity 2018-043-FA, (CSV text and Esri point shapefile, GCS WGS 84)
Abstract:
In September 2018, the USGS Woods Hole Coastal and Marine Science Center (WHCMSC), in collaboration with the US Army Corps of Engineers (USACE), conducted high-resolution geophysical mapping and sediment sampling to determine the distribution of historical mine tailings on the floor of Lake Superior. Large amounts of waste material from copper mining, locally known as “stamp sands”, were dumped into the lake in the early 20th century, with wide-reaching consequences that have continued into the present day. Mapping was focused offshore of the town of Gay on the Keweenaw Peninsula of Michigan, where ongoing erosion and re-deposition of the stamp sands has buried miles of native, white-sand beaches and is steadily encroaching south onto Buffalo Reef, a large area of cobble/boulder substrate that supports productive fisheries in the lake.
The objectives of this cooperative mapping project are to develop a framework for scientific research and provide baseline information required for management of resources within the coastal zone of northern Michigan. High resolution bathymetry and backscatter data reveal the irregular topography of the shallow, cobble-covered Buffalo Reef, and the relatively smooth, finer-grained sediment that covers adjacent, deeper parts of the lake floor. Previous research used numerous sediment samples to determine the general distribution of mine tailings on the lake floor in this area, but little information existed on the extent and thickness of the surficial deposits. The main priority of this project is to image the near-surface stratigraphy, specifically the surficial sand and mud that threaten to cover the reef, with seismic-reflection profiling systems. In addition to continuous coverage of bathymetric and backscatter data, this report includes a dense grid of closely spaced seismic profiles and an isopach map of sediment thickness, which will guide efforts to mitigate the impacts on Buffalo Reef from contamination by the shifting stamp sands.
Supplemental_Information:
Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-043-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 20200318, Seismic Reflection, EdgeTech SB-424 Chirp shot points collected in the vicinity of Buffalo Reef, Michigan, within Lake Superior during USGS field activity 2018-043-FA, (CSV text and Esri point shapefile, GCS WGS 84): data release DOI:10.5066/P9K4HX8V, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Andrews, Brian D., Barnhardt, Walter A., Foster, David S., Irwin, Barry J., and Nichols, Alex R., 2020, High-resolution geophysical data collected in the vicinity of Buffalo Reef, Michigan, within Lake Superior, U.S. Geological Survey Field Activity 2018-043-FA: data release DOI:10.5066/P9K4HX8V, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation:Andrews, B.D., Barnhardt, W.A., Foster, D.S., Irwin, B.J., and Nichols, A.R., 2019, High-resolution geophysical data collected in the vicinity of Buffalo Reef, Michigan, within Lake Superior, U.S. Geological Survey Field Activity 2018-043-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9K4HX8V
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -88.2399889
    East_Bounding_Coordinate: -88.132397
    North_Bounding_Coordinate: 47.225725
    South_Bounding_Coordinate: 47.152425
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5ddeb161e4b04a30051b9e15?name=2018-043-FA_Edgetech424_500sht_browse.jpg (JPEG)
    Thumbnail image of chirp seismic-reflection 500-interval shot points from Lake superior, MI.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 18-Sep-2018
    Ending_Date: 25-Sep-2018
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Entity point (707)
    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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is WGS 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    2018-043-FA_Edgetech424_500shot
    SB-424 500-interval shot points for survey 2018-043-FA in Lake Superior, MI. (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    East
    Easting coordinate in UTM Zone 16 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:406021.56
    Maximum:414253.08
    Units:meters
    Resolution:0.01
    North
    Northing coordinate in UTM Zone 16 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:5222842.22
    Maximum:5230787.3
    Units:meters
    Resolution:0.01
    Lon
    Longitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:-88.132397
    Maximum:-88.239889
    Units:decimal degrees
    Resolution:1E-06
    Lat
    Latitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:47.152425
    Maximum:47.224897
    Units:decimal degrees
    Resolution:1E-06
    LineName
    Name of the trackline along which seismic-reflection data were collected in the format: LineNumberFileNumber (i.e.'l1f1_s') or TransitNumberFileNumber (i.e. 'transit2f1'). (Source: U.S. Geological Survey) Character set
    ImageName
    PNG image name of seismic-reflection profile corresponding to survey line. (Source: U.S. Geological Survey) Character set
    Shot
    Shot number (values are first, last, and every 500 shot between). (Source: U.S. Geological Survey)
    Range of values
    Minimum:30
    Maximum:15845
    Units:shot
    Resolution:1
    Year
    Calendar year the data were collected YYYY. (Source: U.S. Geological Survey) Character set
    JD_UTC
    Julian day and UTC time for first, last, and every 500 shot point between of the survey line in the format: JD:HH:MM:SS; Julian day is the integer number (although recorded here in text string format) representing the interval of time in days since January 1 of the year of collection. (Source: U.S. Geological Survey) Character set
    Old_East
    pre-layback calculation Easting coordinate in UTM Zone 16 meters, WGS84. (Source: U.S. Geological Survey)
    Range of values
    Minimum:406017.64
    Maximum:414248.13
    Units:meters
    Resolution:0.01
    Old_North
    pre-layback calculation Northing coordinate in UTM Zone 16 meters, WGS84. (Source: U.S. Geological Survey)
    Range of values
    Minimum:5222844.22
    Maximum:5230793.44
    Units:meters
    Resolution:0.01
    SurveyID
    WHCMSC field activity identifier (e.g. "2018-043-FA" where 2018 is the survey year, 043 is survey number of that year, and FA is Field Activity). (Source: U.S. Geological Survey) Character set
    VehicleID
    Survey vessel name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Sonar device used to collect seismic-reflection data. (Source: U.S. Geological Survey) Character set
    Entity_and_Attribute_Overview:
    Each point feature in this shapefile can be hyperlinked to a corresponding PNG image in ArcGIS (see the 2018-043-FA_Edgetech424_Images.zip archive accompanying 2018-043-FA_Edgetech424_Images_meta.xml available from the larger work citation). The fist, last, and multiple of 500 shot features in 2018-043-FA_Edgetech424_500sht.shp (available from the larger work citation) correspond to the x-axis ticks on the PNG images.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: David S. Foster
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    US

    508-548-8700 x2271 (voice)
    508-457-2310 (FAX)
    dfoster@usgs.gov

Why was the data set created?

This dataset contains 500 shot point navigation and unique shot point navigation for approximately 272 km of chirp seismic-reflection data collected by the U.S. Geological Survey during cruise 2018-043-FA along Traverse Bay, Lake Superior. This information allows for spatial correlation of chirp seismic-reflection profiles images with other geophysical and sample data for investigating lake-floor morphology and stratigraphy in the area.

How was the data set created?

  1. From what previous works were the data drawn?
    SEG-Y SB-424 data (source 1 of 1)
    U.S. Geological Survey, unpublished material, SB-424 trackline data.

    Type_of_Source_Media: disc
    Source_Contribution:
    Chirp seismic data were collected using an EdgeTech 3100 portable sub-bottom profiling system and an SB-424 towfish (4-24 kHz), which was towed from a port side davit on the R/V Rafael with the transducer approximately 2 m below the water line, and 8.5 meters astern of the DGPS antenna mounted atop the port side of the cabin. Chesapeake Technology SonarWiz (version 6.05.0011) seismic acquisition software was used to control the 3100 topside unit, digitally log trace data in the SEG-Y Rev. 1 format (IEEE floating point), and record GPS navigation coordinates to the SEG-Y trace headers (in arc seconds of Latitude and Longitude, multiplied by a scalar of 360000). Data were acquired using a 250 milliseconds (ms) shot rate, a 5-ms pulse length, and a 4 to 24 kHz frequency sweep at 30 to 50 percent power. Traces were recorded with a 23-microsecond sample interval over lengths of approximately 100 ms.
  2. How were the data generated, processed, and modified?
    Date: Sep-2018 (process 1 of 4)
    PROCESS STEP 1: PROCESS STEP 1: SIOSEIS (version 2015.3.1), Seismic Unix (version 4.2), and Shearwater Reveal (version 2019) were used to process SEG-Y data, create navigation files, and plot images. The processing flow and scripts used to produce navigation files including trackline shapefiles are summarized below and in the following processing steps.
    1) SIOSEIS was used to read the raw SEG-Y files, extract the envelope-detected trace, renumber shots starting from one, and write out new SEG-Y files.
    2) Reveal was use to run the following flows:
    A) read_segy.flow - SegyTapeRead read the traces. HeaderMath and UTMLatLong were used to convert the source lat/lon positions from seconds of arc to decimal degrees, project them to UTM Zone 16N WGS 84 meters, and write each to new header words (NRP_LAT, NRP_LON, NRP_X, and NRP_Y). DBWrite wrote the UTM positions for the first channel of each FFID to an internal Reveal database table. Finally, Output wrote the traces to a new file "*.sht-raw.seis" in the internal OpenCPS format.
    B) layback_shift.flow - Input read the "*.seis" file and sorted the traces to FFID/CHANNEL. The custom Python module ShotlineLayback (developed by Nathan Miller of USGS-WHCMSC) was used to define the measured horizontal offset between the DGPS antenna and the SB-424 transducer (-8.5 m). The algorithm interpolated a sail line from the source shot positions (NRP_X and NRP_Y), then computed layback positions for the SB-424 shots by translating them back along the sail by the measured offset. ApplyStatic was used to shift the traces down by 2.7 ms to account for the approximate 2 m tow depth of the SB-424 (the sound speed of 1500 m/s. Output wrote the shifted traces to a new SEG-Y files in which the trace header words SRC_X, SRC_Y represent the calculated layback coordinates, and REC_X, REC_Y maintain the original DGPS coordinates.
    3) The SIOSEIS script read424 was used to read layback and static corrected SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, including shot number, pre-layback and layback longitude and latitude, year, Julian day, and time of day (UTC). Header information from each SEG-Y file was saved to text files after an AWK (no version) filter was used to maintain the first and last shots, shots at multiples of 100, 500, and shots with unique navigation coordinates. Geographic coordinates (WGS 84) were converted to UTM zone 16 N coordinates (WGS 84) using Proj (version 4.9.3). End shots and shots at multiples of 100 may not have unique navigation coordinates. Separate text files containing the first and last shots and even 500 shot intervals were also saved. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile images. Read424 called a Python script 424inlbtoSQL18043.py, written by Wayne Baldwin (USGS-WHCMSC), which imported the CSV files to a Spatialite (version 4.3.0) enabled SQLite (version 3.21.0) database, creating two tables containing point geometries for the unique and 500 shot interval navigation. The script also created line geometries from the unique navigation (sorted by LineName and Shot) and wrote them to an additional database table. The tracklines are based on all the shot navigation.
    These process steps and all subsequent process steps were conducted by the same person - David Foster. Person who carried out this activity:
    U.S. Geological Survey
    Attn: David S. Foster
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov
    Date: Sep-2019 (process 2 of 4)
    PROCESS STEP 2: The SB-424 500 shot features were added (Add Data) into ArcMap (version 10.3.1) from the SQLite database, then exported (Right click on database feature class >Data> Export Data) to the new Esri polyline shapefile 2018-043-FA_Edgetech424_500sht.shp
    Date: 07-Aug-2020 (process 3 of 4)
    Added keywords section with USGS persistent identifier as theme keyword. 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: 25-Jan-2021 (process 4 of 4)
    Changed the digital transfer format name from digital data to something more specific, as well as adding a second digital form to account for the additional data formats. Changed the series issue from a URL to the DOI number. 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
  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?
  2. How accurate are the geographic locations?
    The EdgeTech SB-424 subbottom profiler was towed from a port side davit on the R/V Rafael with the transducer approximately 2 meters below the water line, and 8.5 meters astern of the DGPS antenna mounted atop the port side of the cabin roof. Navigation data for the SB-424 were collected using a Hemisphere Differential GPS (DGPS) receiver. Positioning data were recorded using Chesapeake Technology SonarWiz (v 6.05.0011) acquisition software, which logged positioning coordinates to individual trace headers SEG-Y format. DGPS horizontal positional accuracy is assumed to be within 2 m; the layback position of the transducer relative to the DGPS antenna was accounted for during processing.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Data were not collected on the following dates because of weather: September 20-21 (JD263-264). Sections of tracklines where navigation was recorded but no seismic data were logged are not included such as during testing, some turns, and very short files.
  5. How consistent are the relationships among the observations, including topology?
    Chirp seismic-reflection profile data were collected on 9/18/2018 (JD261) between 13:45 and 19:38 (UTC), 9/19/18 (JD262 between 13:21 and 20:48 (UTC), 9/22/2018 (JD265) between 13:01 and 21:50 (UTC), 9/25/2018 (JD268) between 12:40 and 21:26 (UTC) . Line numbering begins with l1f1 and ends with l59f1. There are four transit lines named transit1, transit2, transit2f1, and transit3. There is a starting shot point (30) and ending shot point (x) with even 500-shot intervals in the shapefile for each seismic trackline. The CSV file contains unique shot point navigation. No duplicate navigation fixes exist for multiple shots. The attribute field 'ImageName' lists the PNG profile image included in "2018-043-FA_Edgetech424_Images.zip" (available from the larger work citation) that corresponds to each line feature. One image exists for each feature.

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:
Public domain data from the U.S. Government are freely re-distributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    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? USGS data release 2018-043-FA seismic-reflection trackline data from Lake Superior, MI: includes the shapefile 2018-043-FA_Edgetech424_Tracklines.shp, the browse graphic 2018-043-FA_Edgetech424_Tracklines_browse.jpg, and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file 2018-043-FA_Edgetech424_Tracklines_meta.xml.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    To utilize these data, the user must have software capable of reading shapefile format, or GIS software capable of utilizing web mapping or feature services.

Who wrote the metadata?

Dates:
Last modified: 25-Jan-2021
Metadata author:
U.S. Geological Survey
Attn: David S. Foster
Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2271 (voice)
(508) 457-2310 (FAX)
dfoster@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9K4HX8V/2018-043-FA_Edgetech424_500sht_meta.faq.html>
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