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Prepared in cooperation with the U.S. Fish and Wildlife Service

Archive of Digital Chirp Subbottom Profile Data Collected During USGS Cruise 14BIM05 Offshore of Breton Island, Louisiana, August 2014

By Arnell S. Forde,¹ James G. Flocks,¹ Dana S. Wiese,¹ and Jake J. Fredericks²

¹U.S. Geological Survey
²Cherokee Nation Technology Solutions

U.S. Department of the Interior
U.S. Geological Survey

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).

Information Statement

This Digital Versatile Disc (DVD) publication was prepared by an agency of the United States Government. Although these data were processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein 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.

System Requirements

This disc is readable on any computing platform with standard DVD driver software installed. The minimum software requirements are a Web browser, a portable document format (PDF) reader, and a text editor. If you cannot fully access the information on this page, please contact USGS Information Services at infoservices@usgs.gov or 1-888-ASK-USGS.

Getting Started

To access the information contained on this disc, use a Web browser to open the file index.html. This report has eight sections: Home, Abbreviations, Disc Contents, Navigation Data and Maps, Subbottom Profiles, Field Activity Logs, FGDC Metadata, and Software. Links at the top and bottom of each page provide access to these sections. This report contains links to the USGS and collaborators or other resources that are only accessible if the Internet is available while viewing these documents.

Disc Organization

This disc contains a readme (3-Kilobyte [KB] text file) document, which provides a brief description of the report; a folder containing Society of Exploration Geophysicists (SEG) Y binary data files; Geographic Information System (GIS) files used to create the trackline map; and all the Hypertext Markup Language (HTML) files, folders, and images used to produce the Web pages included in this report. The Disc Contents page contains a diagram with locations and links to all files and folders contained on this disc.

Project Summary

From August 11 to 31, 2014, the U.S. Geological Survey (USGS), in cooperation with the U.S. Fish and Wildlife Service (USFWS), conducted a geophysical survey to investigate the geologic controls on barrier island framework and long-term sediment transport offshore of Breton Island, Louisiana as part of a broader USGS study on Barrier Island Mapping (BIM). Additional details related to this activity can be found by searching the USGS's Coastal and Marine Geoscience Data System (CMGDS), for field activity 2014-317-FA (also known as 14BIM05). These surveys were funded through the USGS Coastal and Marine Geology Program (CMGP) and the Louisiana Outer Coast Early Restoration Project. This report serves as an archive of unprocessed digital chirp subbottom data, trackline maps, navigation files, Geographic Information System (GIS) files, Field Activity Collection System (FACS) logs, and formal Federal Geographic Data Committee (FGDC) metadata. Gained digital images of the seismic profiles are also provided. Refer to the Abbreviations page for explanations of acronyms and abbreviations used in this report.

All chirp systems use an acoustic signal of continuously varying frequency; the EdgeTech 512i system used during this survey produced high-resolution, shallow-penetration (typically less than 50 milliseconds [ms]) profile images of sub-seafloor stratigraphy. The towfish contains a transducer that transmits and receives acoustic energy and typically is towed 1–2 meters (m) below the sea surface. As transmitted acoustic energy intersects density boundaries, such as the seafloor or sub-surface sediment layers, some energy is reflected back toward the transducer, received, and recorded by a Personal Computer (PC)-based seismic acquisition system. This process is repeated at regular intervals (for example, 0.125 seconds (s)) and returned energy is recorded for a specific duration (for example, 50 ms). In this way, a two-dimensional (2-D) vertical image of the shallow geologic structure beneath the ship's track is produced. Figure 2 displays the acquisition geometry. Refer to table 1 for a summary of acquisition parameters and table 2 for trackline statistics.

The archived trace data are in standard SEG Y rev. 0 format (Barry and others, 1975); the first 3,200 bytes of the card image header are in American Standard Code for Information Interchange (ASCII) format instead of Extended Binary Coded Decimal Interchange Code (EBCDIC) format. The SEG Y files are available on the DVD version of this report or online, downloadable via the USGS Coastal and Marine Geoscience Data System (http://cmgds.marine.usgs.gov). The data are also available for viewing using GeoMapApp (http://www.geomapapp.org) and Virtual Ocean (http://www.virtualocean.org) multi-platform open source software. The Web version of this archive does not contain the SEG Y trace files. To obtain the complete DVD archive, contact USGS Information Services at 1-888-ASK-USGS or infoservices@usgs.gov. The SEG Y files may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU) (Cohen and Stockwell, 2010). See the How To Download SEG Y Data page for download instructions. The printable profiles are provided as Graphics Interchange Format (GIF) images processed and gained using SU software and can be viewed from the Profiles page or by using the links located on the trackline maps; refer to the Software page for links to example SU processing scripts.

Detailed information about the navigation system used can be found in table 1 and the FACS logs. To view the trackline map and navigation files, and for more information about these items, see the Navigation page.

Acknowledgments

Funds for this report are part of project funds for the Louisiana Outer Coast Early Restoration Project, obtained by the natural resource trustees for the Deepwater Horizon Oil Spill, pursuant to the Framework for Early Restoration Addressing Injuries Resulting from the Deepwater Horizon Oil Spill executed April 20, 2011. USFWS is the project lead for the North Breton Island Barrier Island Restoration project.

The authors thank the research vessel (R/V) Tommy Munro crew (University of Southern Mississippi/Gulf Coast Research Laboratory - Biloxi, Miss.) for their assistance in data collection. This document was improved by the reviews of Noreen Buster and Karen Morgan of the USGS - CMGP, St. Petersburg, Fla.

Disc Image Credit: Descloitres, J., Moderate Resolution Imaging Spectroradiometer (MODIS) Land Rapid Response Team at the NASA Goddard Space Flight Center, 2001, Louisiana.A2001361.1640.250m.jpg, accessed on July 10, 2015, at http://visibleearth.nasa.gov/view_rec.php?id=2364.

References Cited

Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, no. 2, p. 344–352. [Also available at https://dx.doi.org/10.1190/1.1440530.]

Cohen, J.K., and Stockwell, J.W., Jr., 2010, CWP/SU–Seismic Un*x Release No. 41—An open source software package for seismic research and processing, Center for Wave Phenomena, Colorado School of Mines Web page, accessed June 11, 2015, at http://www.cwp.mines.edu/cwpcodes/.

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., accessed October 15, 2014, at http://pubs.er.usgs.gov/usgspubs/ofr/ofr92590.

Suggested Citation

Forde, A.S., Flocks, J.G., Wiese, D.S., and Fredericks, J.J., 2016, Archive of digital chirp subbottom profile data collected during USGS cruise 14BIM05 offshore of Breton Island, Louisiana, August 2014: U.S. Geological Survey Data Series 972, 2 DVDs, https://dx.doi.org/10.3133/ds972.

ISSN 2327-638X (online)

ISSN 2333-0481 (DVD)