Seismic Reflection, EdgeTech SB-512i chirp shot points, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (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-512i chirp shot points, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (CSV text and Esri point shapefile, GCS WGS 84)
Abstract:
High resolution bathymetric, sea-floor backscatter, and seismic-reflection data were collected offshore of southeastern Louisiana aboard the research vessel Point Sur on May 19-26, 2017, in an effort to characterize mudflow hazards on the Mississippi River Delta front. As the initial field program of a research cooperative between the U.S. Geological Survey, the Bureau of Ocean Energy Management, and other Federal and academic partners, the primary objective of this cruise was to assess the suitability of sea-floor mapping and shallow subsurface imaging tools in the challenging environmental conditions found across delta fronts (for example, variably distributed water column stratification and widespread biogenic gas in the shallow subsurface). Approximately 675 kilometers (km) of multibeam bathymetry and backscatter data, 420 km of towed chirp data, and 550 km of multichannel seismic data were collected. Varied mudflow (gully, lobe), prodelta morphologies, and structural features were imaged in selected survey areas from Pass a Loutre to Southwest Pass.
Supplemental_Information:
Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-003-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 2018, Seismic Reflection, EdgeTech SB-512i chirp shot points, USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (CSV text and Esri point shapefile, GCS WGS 84): data release DOI:10.5066/F7X929K6, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Baldwin, Wayne E., Ackerman, Seth D., Worley, Charles R., Danforth, William W., and Chaytor, Jason D., 2018, High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA: data release DOI:10.5066/F7X929K6, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Baldwin, W.E., Ackerman, S.D., Worley, C.R., Danforth, W.W., and Chaytor, J.D, 2018, High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA: U.S. Geological Survey data release, https://doi.org/10.5066/F7X929K6.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -89.554864
    East_Bounding_Coordinate: -88.862700
    North_Bounding_Coordinate: 29.285489
    South_Bounding_Coordinate: 28.776347
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5a947587e4b069906068fc24/?name=2017-003-FA_512i_500sht_browse.jpg (JPEG)
    Thumbnail image of chirp seismic-reflection shot points at 500-interval spacing from the Mississippi River Delta front offshore of southeastern Louisiana.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 21-May-2017
    Ending_Date: 24-May-2017
    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 Vector data set. It contains the following vector data types (SDTS terminology):
      • Point (611)
    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?
    2017-003-FA_512i_500shot
    512i 500-interval shot points for survey 2017-003-FA along the Mississippi River Delta front. (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:250719.13
    Maximum:318664.74
    Units:meters
    Resolution:1
    North
    Northing coordinate in UTM Zone 16 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:3185623.16
    Maximum:3241088.49
    Units:meters
    Resolution:1
    Lon
    Longitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:-89.554864
    Maximum:-88.8627
    Units:degrees
    Resolution:1E-06
    Lat
    Latitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:28.776347
    Maximum:29.285489
    Units:degrees
    Resolution:1E-06
    LineName
    Name of the trackline along which seismic-reflection data were collected in the format: Line-number (i.e.'Line-0002'). (Source: U.S. Geological Survey) Character set
    ImageName
    PNG image name of seismic-reflection profile corresponding to survey line. The '_s' refers to the image file for data that has been through swell filter processing. (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:1
    Maximum:12360
    Units:shot
    Resolution:1
    Year
    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
    SurveyID
    WHCMSC field activity identifier (e.g. "2017-003-FA" where 2017 is the survey year, 003 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:
    The shot locations in the shapefile can be hyperlinked to the PNG seismic-reflection image corresponding to the line name in ArcGIS (see the 2017-003-FA_512i_Images.zip achive accompanying 2017-003-FA_512i_Images_meta.xml available from the larger work citation). The 500 shot point intervals correspond to the x-axis annotations on the PNG images. The unique shot CSV file has the following column headings: East, North, Lon, Lat, LineName, ImageName, Shot, Year, JD_UTC, SurveyID, VehicleID, DeviceID. With the exception of FID and Shape, these headings correspond to those of the shapefile.
    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: Wayne E. Baldwin
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    US

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

Why was the data set created?

This dataset contains 500 shot point navigation and unique shot point navigation for approximately 420 km of chirp seismic-reflection data collected by the U.S. Geological Survey during cruise 2017-003-FA along the Mississippi River Delta front offshore of southeastern Louisiana. This information allows for spatial correlation of chirp seismic-reflection profiles images with other geophysical and sample data for investigating sea-floor morphology and geologic framework in the area.

How was the data set created?

  1. From what previous works were the data drawn?
    SEG-Y 512i data (source 1 of 1)
    U.S. Geological Survey, unpublished material, 512i shot point trackline data.

    Type_of_Source_Media: disc
    Source_Contribution:
    Chirp seismic data were collected using an EdgeTech Geo-Star FSSB sub-bottom profiling system and an SB-0512i towfish (0.5-12 kHz), which was mounted on a catamaran and towed astern of the R/V Point Sur of Gulfport, MS. Chesapeake Technology's SonarWiz (version 6.05.0011) seismic acquisition software was used to control the Geo-Star 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 100). Data were acquired using shot rates between 250 and 750 milliseconds (ms), a 30-ms pulse length, and a 0.5 to 7.2 kHz frequency sweep. Traces were recorded with a 46-microsecond sample interval over lengths between approximately 180 and 700 ms.
  2. How were the data generated, processed, and modified?
    Date: Dec-2017 (process 1 of 2)
    Scripts within SIOSEIS (version 2015.3.1) and Seismic Unix (version 4.2) 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 (version 2015.3.1) was used to read SEG-Y files, renumber shots starting from one, extract the envelope-detected trace, and write out new SEG-Y files. The original shot numbers, which were assigned by SonarWiz sequentially over the duration of an acquisition session despite SEG-Y file changes, are preserved in the raw SEG-Y data.
    2) The SIOSEIS script Sio_medianstk was used to minimize cross talk from the multichannel seismic acquisition sources (boomer and sparker) with a two-trace median stack (trim 50 percent of the values furthest from the median amplitude) and improve water bottom picking. This script was used for all lines even when multi-channel acquisition was not simultaneously occurring, due to the improvements made to water bottom picks.
    3) The script Read512i_mstk was used to read median filtered stacked and renumbered SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, including shot number, longitude, 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 4.6.0). 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. Read512i_mstk called a Python script 512itoSQL17003.py, written by Wayne Baldwin, which imported the CSV files to a Spatialite (version 4.3.0) enabled SQLite (version 3.21.0) database.
    These process steps and all subsequent process steps were conducted by the same person - Wayne Baldwin. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Wayne E. Baldwin
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2226 (voice)
    (508) 457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Dec-2017 (process 2 of 2)
    The 512i 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 point shapefile 2017-003-FA_512i_500sht.shp
  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-0512i subbottom profiler was mounted on a catamaran sled and towed at the sea surface approximately 40 m astern of the M/V Scarlett Isabella. The transducer depth below water line was 0.5 meters below catamaran floats. Navigation data for the 512i were collected using a Wide Area Augmentation System (WAAS) enabled Garmin Differential GPS (DGPS) receiver, which was located on the catamaran sled and connected to the acquisition computer via a serial cable. Positioning data were recorded in SonarWiz (version 6.05.0011) acquisition software, which logged positioning coordinates to individual trace headers SEG-Y format. WAAS enabled GPS horizontal positional accuracy is assumed to be within 2 m; however, horizontal position uncertainty increases with sonar and sled motion, which was not compensated for at the sonar transducer.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    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. There are no Line-0001, Line-0004, Line-0016 or Line-0017.
  5. How consistent are the relationships among the observations, including topology?
    Chirp seismic-reflection profile data were collected continuously throughout the cruise except during two periods of inclement weather and rough sea states: 19:23 (UTC) 5/21/17 (JD141) - 02:17 5/22/17 (JD142) and 10:45 5/23/17 - 17:51 5/23/17 (JD143). Chirp data acquisition ceased at 16:23 on 5/24/17 (JD 144) due to a malfunctioning digitizer in the Edgetech topside unit. There is a starting shot point (1) 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 "2017-003-FA_512i_Images.zip" (available from the larger work citation) that corresponds to each line.

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 redistributable 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
    Federal Center
    Denver, CO

    1-888-275-8747 (voice)
  2. What's the catalog number I need to order this data set? USGS data release 2017-003-FA 512i shot point data from the Mississippi River Delta front area: includes the shapefile 2017-003-FA_512i_500sht.shp, the browse graphic 2017-003-FA_512i_500sht_browse.jpg, a CSV file of unique shot point locations (2017-003-FA_512i_shot-nav.csv), and the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file 2017-003-FA_512i_500sht_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. The CSV file can be read with a text editor.

Who wrote the metadata?

Dates:
Last modified: 28-Feb-2018
Metadata author:
U.S. Geological Survey
Attn: Wayne E. Baldwin
Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2226 (voice)
(508) 457-2310 (FAX)
wbaldwin@usgs.gov
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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