Archive of Digital Boomer Seismic Reflection Data Collected During USGS Cruise 97CCT01 Offshore of Central South Carolina, June 1997

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Frequently anticipated questions:

What does this data set describe?

Title:
Archive of Digital Boomer Seismic Reflection Data Collected During USGS Cruise 97CCT01 Offshore of Central South Carolina, June 1997
Abstract:
In June of 1997, the U.S. Geological Survey, in cooperation with Coastal Carolina University, conducted a geophysical survey of the shallow geologic framework of the continental shelf offshore of central South Carolina from the Isle of Palms to Bull Island. This report serves as an archive of unprocessed digital boomer seismic reflection data, trackline maps, navigation files, GIS information, observers' logbooks, Field Activity Collection System (FACS) logs, and formal FGDC metadata. Filtered and gained digital images of the seismic profiles are also provided. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU). Example SU processing scripts and USGS software for viewing the SEG-Y files (Zihlman, 1992) are also provided.
For more information on the seismic surveys see http://walrus.wr.usgs.gov/infobank/g/g197sr/html/g-1-97-sr.meta.html
These data are also available via GeoMapApp (http://www.geomapapp.org/) and Virtual Ocean ( http://www.virtualocean.org/) earth science exploration and visualization applications.
Supplemental_Information:
The USGS Florida Integrated Science Center (FISC) - St. Petersburg assigns a unique identifier to each cruise or field activity. For example, 97CCT01 tells us the data were collected in 1997 for the Coastal Change and Transport (CCT) Project and the data were collected during the first field activity for that project in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the cruise ID. To differentiate between lines collected on different days, the date was added to the beginning of each trackline name. For example, line SB_1 collected on June 1 became line 601_SB_1, and line SB_1 collected on June 2 became line 602_SB_1. The boomer plate is an acoustic energy source that consists of capacitors charged to a high voltage and discharged through a transducer in the water. The transducer is towed on a sled at the sea surface and when discharged emits a short acoustic pulse, or shot, that propagates through the water and sediment column. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by the receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (e.g., 0.5 s) and recorded for specific intervals of time (e.g., 100 ms). In this way, a two-dimensional vertical image of the shallow geologic structure beneath the ship track is produced. A Huntec power supply provided 120-480 joules per shot. Reflected energy was received by an Innovative Transducers, Inc. (ITI) ST-5 streamer and recorded by Delph Seismic acquisition software. The streamer, which contains 10 hydrophones evenly spaced over a length of 6 m, was positioned parallel to the boomer sled and laterally separated from it by about 7 m. Refer to figure 1 included with this archive (Data Series 203) for a diagram of acquisition geometry. The sample frequency of the data was 16 kHz, and record length was 100-250 ms. Based on survey speeds of 3.5-4 knots and a shot rate of every 0.25-0.5 s, shot spacing was about 0.5-1 m. The unprocessed seismic data are stored in SEG-Y, integer, Motorola format, which is a standard digital format that can be read and manipulated by most seismic processing software packages (Barry and others, 1975). The SEG-Y formatted trace files have a .TRA extension. Additional recording parameters for each trace file can also be found in the .PAR file associated with each .TRA file. However, the .PAR and .PLN files included here are only needed to process or display the data with Delph Seismic software. Also provided are example Seismic Unix scripts that allow the user to strip off navigation fixes from the SEG-Y headers, along with a fix for every 500 shots, and produce a filtered and gained GIF image of each profile.
  1. How might this data set be cited?
    Calderon, Karynna, Dadisman, Shawn V., Kindinger, Jack L., Flocks, James G., Harris, M. Scott, and Thompson, Phillip R., 2005, Archive of Digital Boomer Seismic Reflection Data Collected During USGS Cruise 97CCT01 Offshore of Central South Carolina, June 1997: U.S. Geological Survey Data Series 203, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -79.814182
    East_Bounding_Coordinate: -79.558938
    North_Bounding_Coordinate: 32.889748
    South_Bounding_Coordinate: 32.735321
  3. What does it look like?
    http://pubs.usgs.gov/ds/2006/203/maps/all.jpg (JPEG)
    Trackline map of all digital boomer seismic reflection data collected during USGS Cruise 97CCT01. This map was created at a scale of 1:120,000. Refer to the Lineage section below for the trackline map creation process.
    http://pubs.usgs.gov/ds/2006/203/maps/area_a.jpg (JPEG)
    Trackline map of digital boomer seismic reflection data collected in Area A (refer to Area A of the full survey area map) during USGS Cruise 97CCT01. This map was created at a scale of 1:45,000. Refer to the Lineage section below for the trackline map creation process.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Jun-1997
    Ending_Date: 04-Jun-1997
    Currentness_Reference:
    Data collection interval
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Seismic Reflection Profile Section
  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 (latitude and longitude and UTMs) for each shot are provided as ASCII text files, along with the date and time (UTC) the shot was recorded.
      This is a Point data set.
    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 WGS84.
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Binary data file: Trace data are available as binary files in SEG-Y format. These files have a .TRA extension and range in size from 11.7 to 167.1 MB.
    Entity_and_Attribute_Overview:
    Graphic image file: Profiles are GIF images that range in size from 343 KB to 2.7 MB. Trackline maps, which range in size from 113 to 121 KB, are JPEG images that contain links to the seismic profile GIF images.
    Entity_and_Attribute_Overview:
    Navigation file: Navigation files are available as ASCII text files. Raw navigation files range in size from 19 to 194 KB, the edited navigation file measures 2.3 MB, and the edited 500-shot-interval location file measures 25.9 KB.
    Entity_and_Attribute_Overview:
    GIS file: The GIS project used to create the trackline maps is provided as a zip file composed of map documents, shapefiles, and metadata. The map documents range in size from 491 to 518 KB, and the shapefiles range in size from 3.61 KB to 29 MB.
    Entity_and_Attribute_Detail_Citation:
    Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, n. 2, p. 344-352. Also available online at: http://www.seg.org/publications/tech-stand.
    Entity_and_Attribute_Detail_Citation:
    Zihlman, F.N., 1992, DUMPSEGY V1.0: A program to examine the contents of SEG-Y disk-image seismic data: U.S. Geological Survey Open-File Report 92-590, 28 p.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Karynna Calderon
    • Shawn V. Dadisman
    • Jack L. Kindinger
    • James G. Flocks
    • M. Scott Harris
    • Phillip R. Thompson
  2. Who also contributed to the data set?
    Funding and/or support for this study were provided by the USGS Coastal and Marine Geology Program and Coastal Carolina University. We thank R/V G.K. Gilbert captain Keith A. Ludwig of the USGS in St. Petersburg, Florida, for his assistance in data collection. This document was improved by the reviews of Kathryn E.L. Smith (USGS) and Noreen A. Buster (ETI Professionals, Inc., contracted by the USGS) at the FISC - St. Petersburg, Florida.
  3. To whom should users address questions about the data?
    Jack Kindinger
    U.S. Geological Survey
    Oceanographer
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 803-8747, ext. 3018 (voice)
    jkindinger@usgs.gov

Why was the data set created?

The data archived here were collected in cooperation with Coastal Carolina University as part of the USGS Coastal Change and Transport (CCT) Project.

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: 2003 (process 1 of 6)
    Boomer processing: The SEG-Y data were processed with Seismic Unix to produce GIF images of the seismic profiles included in this report. A representative boomer processing sequence consisted of: 1) Bandpass filter: 300-500-2500-3000 Hz, 2) Automatic gain control, 3) Postscript display, and 4) Conversion of Postscript image to a GIF image.
    Date: 2003 (process 2 of 6)
    Navigation processing: Shotpoint navigation files were extracted from the trace headers of each line using Delph Seismic software and edited to remove spurious data points. These files were then processed with PROJ.4 software (http://www.remotesensing.org/proj) to generate Zone 17 UTMs from latitude and longitude and reformatted for use with Environmental Systems Research Institute (ESRI) GIS software. The 500-shot-interval location files were extracted from the trace headers using Seismic Unix scripts and processed in the same manner as the shotpoint navigation files.
    Date: 2004 (process 3 of 6)
    Trackline map creation: Trackline maps were generated with ESRI ArcView 3.3 and ArcGIS 8.3 software, exported to Adobe Illustrator for further editing, and saved in JPEG format. The maps are unprojected (geographic coordinates, NAD83). The USGS is the originator of all layers except for the South Carolina coastline layer, which is a National Geodetic Survey dataset.
    Date: 2004 (process 4 of 6)
    Data Series preparation: In addition to the process steps described above, the following steps were taken to produce this Data Series: the handwritten logbooks were scanned and made into PDF files, FACS logs were created using the handwritten logs and personal accounts of the crew members, and an HTML-based format was used to present the various parts of this archive.
    Date: 24-Jan-2017 (process 5 of 6)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 13-Oct-2020 (process 6 of 6)
    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
  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?
    The validity or accuracy of marine seismic reflection profiles is highly qualitative and depends on equipment and operating condition variables. Visual inspection of the images rendered from the data did not show any major anomalies.
  2. How accurate are the geographic locations?
    As the seismic reflection data were acquired, the position of the vessel was continuously determined by a Trimble Nav Trac GPS receiver, which is accurate within 15 m. Positions were recorded and written to the trace headers in latitude and longitude about every 3 s. The ASCII navigation files and trackline maps have not been corrected to reflect the approximately 20-m offset between the shotpoint and the GPS antenna. Refer to figure 1 included with this archive (Data Series 203) for a diagram of acquisition geometry.
  3. How accurate are the heights or depths?
    Boomer data are relative to sea level. However, varying recorded static shifts of the data have been known to occur. Therefore, these data are not to be used for bathymetry.
  4. Where are the gaps in the data? What is missing?
    These data are collected along tracklines (2-D) and are therefore inherently incomplete. Geologic details between lines must be inferred. Navigation is missing for the first 115 shots of line 604_SB_1. On the trackline maps, a cross marks the location of the first available navigation fix for this line. Navigation is also intermittent for line 602_SB_1. On the trackline maps, the location of missing navigation data within a line is inferred by linear interpolation of the first and last known data points and is indicated by a dashed yellow line.
  5. How consistent are the relationships among the observations, including topology?
    This data set is from one cruise with consistent instrument calibrations.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None. These data are held in the public domain.
Use_Constraints:
The U.S. Geological Survey and Coastal Carolina University request to be acknowledged as the originators of the data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Shawn Dadisman
    U.S. Geological Survey
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 803-8747, ext. 3029 (voice)
    sdadisman@usgs.gov
    Contact_Instructions:
    Data may be available on-line only by special arrangement with the distributor above.
  2. What's the catalog number I need to order this data set? U.S. Geological Survey Data Series 203
  3. What legal disclaimers am I supposed to read?
    This DVD publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Although all data and software published on this DVD have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and (or) the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data, software, or related materials.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: The SEG-Y standard format (Barry and others, 1975) consists of the following: a 3,600-byte reel identification header, with the first 3,200 bytes consisting of an ASCII header block followed by a 400-byte binary header block, both of which include information specific to line and reel number; a trace data block that follows the reel identification header, with the first 240 bytes of each trace block consisting of the binary trace identification header; and seismic data samples that follow the trace identification header. in format SEG-Y Size: 1230
      Media you can order: DVD (format ISO 9660)
      Note: UNIX, LINUX, DOS, Macintosh
      Data format: The GIS project used to create the trackline maps is composed of map documents, shapefiles, and metadata. Map documents were created using ESRI ArcGIS 8.3 software. The shapefiles provided may also be viewed using other versions of ArcView, ArcGIS, or public domain software ArcExplorer (http://www.esri.com/software/arcexplorer). in format map document, shapefile, metadata Size: 25.6
      Network links: https://pubs.usgs.gov/ds/2006/203/software/arc/arc.zip
      Data format: The SEG-Y standard format (Barry and others, 1975) consists of the following: a 3,600-byte reel identification header, with the first 3,200 bytes consisting of an ASCII header block followed by a 400-byte binary header block, both of which include information specific to line and reel number; a trace data block that follows the reel identification header, with the first 240 bytes of each trace block consisting of the binary trace identification header; and seismic data samples that follow the trace identification header. in format SEGY data download Size: 1230
      Network links: https://cmgds.marine.usgs.gov/data/97cct01/boomer/
    • Cost to order the data: Prices vary.

    • Special instructions:
      Publications are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225-0046 (telephone: 1-888-ASK-USGS, e-mail: infoservices@usgs.gov).
  5. What hardware or software do I need in order to use the data set?
    Use of SEG-Y data requires specialized seismic processing software, such as public domain software Seismic Unix (http://www.cwp.mines.edu/cwpcodes/index.html).

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
Karynna Calderon
CSC, contracted by USGS
Geographer
600 4th Street South
St. Petersburg, FL
USA

(727) 803-8747, ext. 3143 (voice)
kcalderon@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/ds-203metadata.faq.html>
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