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Open-File Report 03-497

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Read-Me

ARCHIVE OF DIGITAL BOOMER SEISMIC REFLECTION
DATA
COLLECTED DURING USGS CRUISES
94GFP01, 95GFP01,
96GFP01, 97GFP01, AND 98GFP02
IN LAKES PONTCHARTRAIN,
BORGNE, AND
MAUREPAS, LOUISIANA, 1994 - 1998

by Karynna Calderon1, Shawn V. Dadisman2, Jack L. Kindinger2,
S. Jeffress Williams3, James G. Flocks2, Shea Penland4, and Dana S. Wiese2

1ETI Professionals, Inc., St. Petersburg, FL 33701
2U.S. Geological Survey, St. Petersburg, FL 33701
3U.S. Geological Survey, Woods Hole, MA 02543
4University of New Orleans, New Orleans, LA 70148

U.S. Geological Survey Open-File Report 03-497


ABSTRACT

The U.S. Geological Survey, in cooperation with the University of New Orleans, the Lake Pontchartrain Basin Foundation, the National Oceanic and Atmospheric Administration, the Coalition to Restore Coastal Louisiana, the U.S. Army Corps of Engineers, the Environmental Protection Agency, and the University of Georgia, conducted five geophysical surveys of Lakes Pontchartrain, Borgne, and Maurepas in Louisiana from 1994 to 1998. This report serves as an archive of unprocessed digital boomer seismic reflection data, trackline maps, navigation files, observers' logbooks, GIS information, and formal FGDC metadata. In addition, a filtered and gained digital GIF image of each seismic profile is provided. Refer to the Acronyms page for expansion of acronyms and abbreviations used in this report.

Note: The web version of this archive does not contain the SEG-Y trace files. These files are very large and would require extremely long download times. To obtain the complete DVD archive, contact USGS Information at 1-888-ASK-USGS or infoservices@usgs.gov.

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). Examples of SU processing scripts and in-house (USGS) software for viewing SEG-Y headers (Zihlman, 1992) are also provided. Processed profile images, trackline maps, navigation files, and formal metadata may be viewed with a web browser, and scanned handwritten logbooks may be viewed with Adobe Reader.

To access the information contained on these discs, open the file 'index.htm' located at the top level of the discs using a web browser. This report also contains hyperlinks to USGS collaborators and other agencies. These links are only accessible if access to the Internet is available while viewing these documents.

PURPOSE

The data archived here were collected as part of a Lake Pontchartrain Basin Geologic Framework and Coastal Processes Study. This work was part of a multidisciplinary evaluation of the geology, geomorphology, coastal processes, and environmental quality of the Lake Pontchartrain Basin. This study is part of the USGS Geologic Framework and Processes (GFP) Project. For further information about this study, refer to http://coastal.er.usgs.gov/pontchartrain.

SUPPLEMENTAL INFORMATION

The USGS Florida Integrated Science Center (FISC) - Coastal and Watershed Studies in St. Petersburg, Florida, assigns a unique identifier to each cruise or field activity. For a detailed description of the method used to assign the cruise ID, see http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html or the formal metadata in this report. For example, 94GFP01 indicates the data were collected in 1994 for the Geologic Framework and Processes Project and that the data were collected during the first field activity for that project in that calendar year.

Detailed information about the navigation systems used for each cruise can be found in Table 1 and the Equipment FACS for each cruise. To view the trackline maps and navigation files, and for more information about these items, see the Navigation page.

The boomer energy source consists of capacitors that are charged to a high voltage and then discharged through a transducer in the water. The transducer is towed on a sled at the sea surface and 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., 500 ms) 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. Figure 1 shows the acquisition geometry for all surveys, and Table 1 displays the acquisition parameters for all cruises. For more information about the acquisition equipment used, refer to the Equipment FACS log for each cruise. Reproductions of all handwritten logbooks collected during each cruise are also provided.

The unprocessed 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 (Barry and others, 1975). For a detailed description of the data format, refer to the SEG-Y Format page. See the How To Download SEG-Y Data page for more information about these files, including instructions on how to download them. GIF images of processed profiles can be viewed from the Profiles page. Refer to the Software page for details about the processing and examples of the processing scripts.

The SEG-Y data files are too large to fit on one disc, so they have been distributed onto two DVDs with the SEG-Y files for 94GFP01, 95GFP01, and 96GFP01 on Disc 1 and the SEG-Y files for 97GFP01 and 98GFP02 on Disc 2. Digital data were not recorded for 94GFP01 lines PON531_1 and LINE_9A and 96GFP01 line pon96_8. No data were collected for 95GFP01 line SBP_A1 and 98GFP02 lines lasi_16 and lasi_48a - lasi_54. The original trace files for 94GFP01 lines PON531_2, PON61_1, PON62_1, PON62_3, LINE_7, LINE_10, LINE_14, LINE_17, LINE_18, and LINE_20; 96GFP01 lines pon96_6, pon96_9, and pon96_24; and 97GFP01 lines pon97_1, pon97_12, pon97_16, and pon97_17 were divided into two or more trace files (e.g., LINE_7 became LINE_7a and LINE_7b) because the original total number of traces exceeded the maximum allowed by the processing system. Navigation is intermittent for 94GFP01 lines PON531_2a, PON61_1a, PON62_3a, and LINE_14a; 95GFP01 line SBP_D; 96GFP01 lines pon96_1 and pon96_25; 97GFP01 lines pon97_8, pon97_12a, pon97_16a, pon97_17a; and 98GFP02 line lasi_58. Navigation is also missing at the start of many 94GFP01, 95GFP01, and 96GFP01 lines.


DISC CONTENTS

Refer to the Disc Contents page for a diagram of the location of all files and folders mentioned in the text. Both discs are identical except for the SEG-Y files. Disc 1 contains the SEG-Y files for 94GFP01, 95GFP01, and 96GFP01, and Disc 2 contains the SEG-Y files for 97GFP01 and 98GFP02.


DISCLAIMER

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code.

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 these DVDs have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or 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 or related materials.


ACKNOWLEDGEMENTS

Funding and/or support for this study were provided by the USGS Coastal and Marine Geology Program, the University of New Orleans (UNO), the Lake Pontchartrain Basin Foundation, the National Oceanic and Atmospheric Administration, the Coalition to Restore Coastal Louisiana, the U.S. Army Corps of Engineers, the Environmental Protection Agency, and the University of Georgia. We thank Rita Byrd, formerly of the USGS in St. Petersburg, Florida, for her field support during boomer data collection. We also thank Bob Seal and Paul Connor of UNO for their work during the vibracoring and other portions of these cruises. We are also grateful to R/V G.K. Gilbert Captains Richard W. Young of the USGS in St. Petersburg, Florida; Kevin Geraghty, formerly of the USGS in St. Petersburg, Florida; and Dave Bennett of Eckerd College for their assistance in data collection. This document was improved by the reviews of Tonya D. Clayton and Asbury H. Sallenger of the USGS in St. Petersburg, Florida.


REFERENCES

Barry, R.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, p. 344-352.

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.


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