Archive of Boomer Seismic Reflection Data Collected During USGS Cruises 01SCC01 and 01SCC02, Timbalier Bay and Offshore East Timbalier Island, Louisiana, June - August 2001

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Frequently anticipated questions:


What does this data set describe?

Title:
Archive of Boomer Seismic Reflection Data Collected During USGS Cruises 01SCC01 and 01SCC02, Timbalier Bay and Offshore East Timbalier Island, Louisiana, June - August 2001
Abstract:
This archive consists of two-dimensional marine seismic reflection profile data collected in Timbalier Bay and in the Gulf of Mexico offshore East Timbalier Island, Louisiana. These data were acquired June 30 - July 9 (01SCC01) and August 1 - 18 (01SCC02), 2001, aboard the R/V G.K. Gilbert and a University of New Orleans 21-foot Proline. Included here are data in a variety of formats including binary, American Standard Code for Information Interchange (ASCII), Hyper Text Markup Language (HTML), Portable Document Format (PDF), Rich Text Format (RTF), Graphics Interchange Format (GIF) and Joint Photographic Experts Group (JPEG) images, and shapefiles. Binary data are in Society of Exploration Geophysicists (SEG) SEG-Y format and may be downloaded for further processing or display. Reference maps and GIF images of the profiles may be viewed with a web browser. The Geographic Information Systems (GIS) map documents provided were created with Environmental Systems Research Institute (ESRI) GIS software ArcView 3.2 and 8.1.
For more information on the seismic surveys see http://walrus.wr.usgs.gov/infobank/g/g401la/html/g-4-01-la.meta.html and http://walrus.wr.usgs.gov/infobank/g/g501la/html/g-5-01-la.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 Center for Coastal and Watershed Studies team in St. Petersburg, Florida, assigns a unique identifier to all seismic data collected during each cruise or field activity. The method used to assign the identifier for the activity is as follows: YYPPP##, where YY stands for the last 2 digits of the year in which the fieldwork is conducted, PPP is a 3-letter abbreviation for the project the data are collected for, and ## is a 2-digit event tag that represents a discreet leg or time period of fieldwork. Here, for example, 01SCC01 tells us the data were collected in 2001 for the Subsidence and Coastal Change Project and that the data were collected during the first field activity for that project in that calendar year. The naming convention the center uses for each seismic line is as follows: yye###a, where yy is the last 2 digits of the year in which the data were collected, e is a 1-letter abbreviation for the equipment type (i.e., c for chirp and b for boomer), ### is a 3-digit number representing a specific track, and a is a 1-letter abbreviation representing the section of a line if recording was prematurely terminated or rerun for quality or acquisition problems. Seismic reflection profiles are acquired by means of an acoustic source (usually generated electronically) and hydrophone or receiver arrays. Both elements are typically towed in the water behind a survey vessel. The sound source 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) and detected at the receiver. This process is repeated at intervals ranging between 100 milliseconds (ms) and 1 second (s) depending on the seismic source employed. In this way, a two-dimensional vertical image of the geologic structure beneath the ship track can be interpreted. The boomer energy source consists of capacitors that are charged to a high voltage and then discharged through a transducer in the water. The frequency range of the source is between 300 and 3,000 hertz (Hz). The transducer was towed on a sled at the sea surface providing 100 joules (J) per shot for lines 01b001-01b046 and 01b082-01b093 and 200 J per shot for lines 01b047-01b080. The reflected energy was received by a streamer and recorded by PC-based Triton Elics Delph Seismic acquisition software. In an attempt to resolve unknown acquisition problems, streamers were switched throughout the first cruise between Innovative Technologies, Inc. (ITI) ST5 and SN Technologies NexGen streamers. Only the NexGen streamer was used for the second cruise. Both streamers contain 10 hydrophones. These are evenly spaced every 2 feet (0.6 m) on the ITI streamer and every 2 m on the NexGen streamer. Only data received by elements 4-7 were summed for lines 01b001-01b028, by elements 5 and 6 for lines 01b029-01b089, and by elements 7 and 8 for lines 01b091-01b093. The streamer was positioned parallel to the boomer sled and laterally separated from it by about 7 m for lines 01b001-01b080, which were collected on the R/V G.K. Gilbert, and by about 4 m for lines 01b082-01b093, which were collected on a 21-foot Proline. The sled was towed about 20 m behind the Global Positioning System (GPS) antenna on the R/V G.K. Gilbert and about 12 m behind on the Proline. No correction for this offset has been made. The sample frequency of the data was 12 kilohertz (kHz). All tracklines were recorded to 100 ms. Based on survey speeds of 3.5-4 knots and a shot rate of every 0.5 s, the shot spacing was about 1 m. Seismic data were stored in SEG-Y format, which is a standard digital format that can be read and manipulated by most seismic processing software packages. The SEG-Y file format includes a 3,200-byte descriptive header that contains detailed information regarding the data acquisition and processing parameters. All data presented here are stored in SEG-Y, integer, Motorola format. The SEG-Y formatted trace data files have a .TRA extension. Additional recording parameters for each seismic data file can also be found in the .PAR file associated with each .TRA file. However, the .PAR and .pln files included are only needed to process or display the data with Triton Elics Delph Seismic software. No SEG-Y data exists for tracklines 01b002 and 01b081. For lines 01b001-01b080, Differential GPS (DGPS) navigation was provided by a CSI DGPS Max WAAS/Beacon DGPS receiver, whose accuracy is within 5 m. The DGPS string was fed to a navigation computer running Hypack software, which converted the data to Zone 15 Universal Transverse Mercator (UTM) coordinates. The navigation was then fed to the Delph Seismic acquisition system approximately every second and recorded in the SEG-Y headers. For lines 01b082-01b093, GPS navigation was provided by a Trimble Centurian P-Code receiver, whose accuracy is within about 100 m. The GPS string was fed directly to the acquisition system approximately every second in latitude and longitude and recorded in the SEG-Y headers. Both UTMs and latitude and longitude are provided for all lines. The data required some editing to remove spurious data values. The edited results were used to generate the trackline maps presented here. The navigation data have not been corrected to reflect the offset between the shotpoint and the GPS antenna. Position fixes for every 500 shots and for the start of lines are also provided as an aid for registering of the data after plotting. All navigation files are stored as flat ASCII text files. The trackline maps provided in this archive are unprojected, set in geographic coordinates, North American Datum 1983 (NAD83). They were created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. These JPEG images are viewable with a web browser. Also included on this disc are the ArcView map documents and shapefiles used to create the trackline maps presented here. The map documents are compatible with ArcGIS 8.x (Windows). The shapefiles can also be viewed using ArcView 3.x or public domain software ArcExplorer 2.0 (Windows) and 4.0 (Windows, Unix, Linux), which can currently be downloaded from the ESRI website at <http://www.esri.com/software/arcexplorer/index.html>. Field Activity Collection System (FACS) logs are available in both HTML and Rich Text Format. Scanned versions of the handwritten logbooks are provided as PDF files. Also included on this disc are example Seismic Unix (SU) 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. These images can then be displayed using a variety of shareware programs such as ImageMagick (Unix, Linux) or a web browser.
  1. How might this data set be cited?
    Calderon, Karynna, Dadisman, Shawn V., Flocks, James G., Kindinger, Jack L., and Wiese, Dana S., 2003, Archive of Boomer Seismic Reflection Data Collected During USGS Cruises 01SCC01 and 01SCC02, Timbalier Bay and Offshore East Timbalier Island, Louisiana, June - August 2001: U.S. Geological Survey Open-File Report 03-274, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -90.394838
    East_Bounding_Coordinate: -90.182451
    North_Bounding_Coordinate: 29.149325
    South_Bounding_Coordinate: 28.963148
  3. What does it look like?
    http://pubs.usgs.gov/of/2003/of03-274/maps/all.jpg (JPEG)
    Trackline map of all boomer seismic reflection data collected during USGS Cruises 01SCC01 and 01SCC02. These data were collected in Timbalier Bay and in the Gulf of Mexico offshore of East Timbalier Island, Louisiana, in June, July, and August of 2001. This map is set in geographic coordinates, NAD83 (unprojected) and was created at a scale of 1:200,000. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating the maps presented in this archive. The roads layer is a Louisiana Oil Spill Coordinator's Office (LOSCO) Environmental Baseline Inventory Dataset 'Louisiana Highway System from LDOTD (Louisiana Department of Transportation) source data, Geographic NAD83, LOSCO (1999) [primary roads].' The rivers layer is a LOSCO data set derived from ESRI/Geographic Data Technology, Inc. (GDT) data that were in turn derived from Bureau of the Census TIGER/Line files. The waterbodies layer is also a LOSCO data set derived from ESRI/GDT data.
    http://pubs.usgs.gov/of/2003/of03-274/maps/area_a.jpg (JPEG)
    Trackline map of boomer seismic reflection data collected in Area A (refer to Area A of the full survey map) of Timbalier Bay, Louisiana, during USGS Cruises 01SCC01 and 01SCC02 in June, July, and August of 2001. This map is set in geographic coordinates, NAD83 (unprojected) and was created at a scale of 1:110,000. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The waterbodies layer is a LOSCO data set derived from ESRI/GDT data.
    http://pubs.usgs.gov/of/2003/of03-274/maps/area_b.jpg (JPEG)
    Trackline map of boomer seismic reflection data collected in Area B (refer to Area B of the full survey map) of the Gulf of Mexico offshore of East Timbalier Island, Louisiana, during USGS Cruises 01SCC01 and 01SCC02 in June, July, and August of 2001. This map is set in geographic coordinates, NAD83 (unprojected) and was created at a scale of 1:110,000. It was created using ESRI GIS software ArcView 3.2 and 8.1, exported to Adobe Illustrator for further editing, and saved for the web in JPEG format. The USGS is not the originator of all layers used in creating this map. The waterbodies layer is a LOSCO data set derived from ESRI/GDT data.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 30-Jun-2001
    Ending_Date: 18-Aug-2001
    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 (both Zone 15 UTMs and latitude and longitude) for each shot location are provided in ASCII position files, along with the time the shot was recorded in Greenwich Mean Time.
    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 0.000009. Longitudes are given to the nearest 0.000009. 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 1/298.25722.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Binary data file: Each profile is available as a binary file in Society of Exploration Geophysicists (SEG) SEG-Y format. A SEG-Y file consists of 1) a 3,200-byte file identification record of ASCII-formatted general information, 2) a 400-byte binary record with information such as sample rate and record length specific to the data set, and 3) multiple records, with one seismic reflection trace per record for boomer data. Each trace record is preceded by a 240-byte trace header containing information such as trace number and acquisition day and time specific to each trace. The trace data are represented as a time series of unitless 16-bit integer or 32-bit real numbers proportional to the reflection coefficient. The SEG-Y file is useful only if you have access to specialized software designed to process and display seismic reflection data. These SEG-Y files have a .TRA extension and range in size from 932 KB to 68.863 MB.
    Entity_and_Attribute_Overview:
    Graphic Image File: Each profile is available as a GIF image. The trackline maps provided are JPEG images that contain hotlinks to the seismic profile GIF images. The profiles range in size from 53 KB to 4.1 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/index_body.html>.

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
    • James G. Flocks
    • Jack L. Kindinger
    • Dana S. Wiese
  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 (CMGP), the University of New Orleans, the U.S. Army Corps of Engineers, and the Louisiana Department of Natural Resources. We thank R/V G.K. Gilbert Captains Dave Bennett of Eckerd College in St. Petersburg, Florida, and Keith A. Ludwig and Richard W. Young of the USGS in St. Petersburg, Florida, for their assistance in data collection. We also thank reviewers Thomas J. Smith and Kimberly K. Yates of the USGS in St. Petersburg, Florida, whose comments improved this document.
  3. To whom should users address questions about the data?
    Jack L. Kindinger
    U.S. Geological Survey
    Oceanographer
    600 4th Street South
    St. Petersburg, FL
    USA

    727-803-3747, ext. 3018 (voice)
    jkindinger@usgs.gov

Why was the data set created?

Marine seismic reflection data are used to image and map sedimentary and structural features of the seafloor and subsurface. These data are useful in mapping stratigraphy and in assessing other submarine geologic characteristics and features. These data were collected as part of a Louisiana Sand Resources Study done in collaboration with the University of New Orleans, the U.S. Army Corps of Engineers, and the Louisiana Department of Natural Resources. This study is part of the U.S Geological Survey (USGS) Subsidence and Coastal Change (SCC) 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: Raw SEG-Y data were processed with Seismic Unix to produce the GIF seismic profiles included in this report. A representative data processing sequence consisted of: 1) Bandpass filter: 300-500-2500-3000 Hz 2) Automatic gain control 3) Postscript display 4) Convert Postscript image to GIF image
    Date: 2003 (process 2 of 6)
    Positional (navigation) data: As the seismic reflection data were acquired, the position of the vessel was continuously determined by a GPS receiver. Positions were recorded approximately every second and written to the SEG-Y header. The ASCII navigation and the 500-shot interval navigation files were extracted from the SEG-Y headers using Seismic Unix scripts.
    Date: 2003 (process 3 of 6)
    Editing navigation: The ASCII navigation files were extracted from the SEG-Y headers and edited to remove spurious data points. The data were then processed using PROJ.4 freeware to convert Zone 15 UTMs to latitude and longitude for lines 01b001-01b080, and to convert latitude and longitude to UTMs for lines 01b082-01b093. The data were also reformatted for use with ESRI ArcView GIS software. ArcView 3.2 was used to create trackline navigation layers that were used in the final ArcView 8.1 map documents.
    Date: 2003 (process 4 of 6)
    Open-file preparation: No processing has been done to the SEG-Y data files provided on this Digital Versatile Disc (DVD). The data were displayed as 8-bit grayscale Postscript files using the Seismic Unix 'psimage' algorithm. The Postscript images were then converted to GIF images.
    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. Data acquisition problems existed during 01SCC01. The result appears to be spatial aliasing of the data in most lines. Visual inspection of the images rendered from the data in 01SCC02 did not show any major anomalies.
  2. How accurate are the geographic locations?
    Positional accuracy for lines 01b001-01b080 was determined with a CSI DGPS Max WAAS/Beacon DGPS receiver, whose accuracy is within about 5 m. The DGPS string was fed to a navigation computer running Hypack software, which converted the data to Zone 15 UTMs. The navigation was then fed to the Delph Seismic acquisition system approximately every second and recorded in the SEG-Y headers. Positional accuracy for lines 01b082-01b093 was determined with a Trimble Centurian P-Code receiver, whose accuracy is within about 100 m. The GPS string was fed directly to the acquisition system approximately every second in latitude and longitude and recorded in the SEG-Y headers. Both UTMs and latitude and longitude are provided for all lines. The navigation data have not been corrected to reflect the offset between the shotpoint and the GPS antenna.
  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 (2D). Therefore, data are inherently incomplete. Geologic details between lines must be inferred. All tracklines were recorded to 100 ms. No digital data exists for tracklines 01b002 and 01b081. There is no navigation for line 01b004 before shot number 123, for line 01b058 between shot numbers 510 and 913, for line 01b087 between shot numbers 1 and 314, for line 01b090 between shot numbers 6,012 and 6,721, or for line 01b091 between shot numbers 4,023 and 4,346.
  5. How consistent are the relationships among the observations, including topology?
    These data sets are from two field activities and two different vessels. Differences occur in navigation and acquisition equipment and acquisition geometry between vessels and field activities. Horizontal accuracy varies with navigation equipment used, and signal-to-noise ratio of the data changes with hydrophone streamers used. However, for most purposes, the profile data are comparable for all systems used. Please refer to Supplemental Information for details of equipment and geometry used for each seismic 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. These data are held in the public domain.
Use_Constraints:
The U.S. Geological Survey requests to be acknowledged as the originator of the data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Shawn V. 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 Open-File Report 03-274
  3. What legal disclaimers am I supposed to read?
    This Digital Versatile Disc (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, make 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 necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Although all data 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 this 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 et al., 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: 2020
      Media you can order: DVD (format UDF (Universal Disc Format))
      Note: UNIX, LINUX, DOS, MAC
      Data format: GIS projects and layers used to create the trackline maps presented in this archive and associated metadata. in format ESRI map document, shapefile, metadata Size: 24.9
      Network links: https://pubs.usgs.gov/of/2003/of03-274/software/arc/arc.zip
      Data format: The SEG-Y standard format (Barry et al., 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: 2020
      Network links: https://pubs.usgs.gov/of/2003/of03-274/segy/01scc01/
      https://pubs.usgs.gov/of/2003/of03-274/segy/01scc02/
    • Cost to order the data: Available from USGS Information Services. Prices vary.

    • Special instructions:
      Most open-file reports are available from USGS Information Services, Box 25286, Federal Center, Denver, CO 80225-0046 (telephone: 1-888-ASK-USGS; email: 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 Unix or Linux-based public domain software Seismic Unix (SU) developed by the Colorado School of Mines Center for Wave Phenomena, which can be downloaded at <http://www.cwp.mines.edu/cwpcodes/index.html>.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
Karynna Calderon
U.S. Geological Survey
Geographer, Data Management Group
600 4th Street South
St. Petersburg, FL
USA

727-803-8747, ext. 3143 (voice)
kcalderon@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/of2003-274metadata.faq.html>
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