Data Series 93
By Karynna Calderon,1 Shawn V. Dadisman,2 Jack L. Kindinger,2 James G. Flocks,2 Robert A. Morton,2 and Dana S. Wiese2
1ETI Professionals, Inc., St. Petersburg, FL 33701.
2U.S. Geological Survey, St. Petersburg, FL 33701.
U.S. Department of the Interior
U.S. Geological Survey
Florida Integrated Science Center - Coastal and Watershed Studies
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In June of 1994 and August and September of 1995, the U.S. Geological Survey, in cooperation with the University of Texas Bureau of Economic Geology, conducted geophysical surveys of the Sabine and Calcasieu Lake areas and the Gulf of Mexico offshore eastern Texas and western Louisiana. 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 GIF image of each seismic profile is provided. Refer to the Acronyms page for expansion of acronyms and abbreviations used in this report.
The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG-Y format (Barry et al., 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 files (Zihlman, 1992) are also provided. 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 firstname.lastname@example.org. Processed profile images, trackline maps, navigation files, and formal metadata may be viewed with a web browser. Scanned handwritten logbooks and Field Activity Collection System (FACS) logs may be viewed with Adobe Reader.
The data archived here were collected in cooperation with the University of Texas Bureau of Economic Geology as part of the USGS Coastal Change and Transport (CCT) Project. For further information about this study, refer to Morton and others (1999).
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 example, 94CCT01 indicates the data were collected in 1994 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. 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 included in this report.
The boomer is an acoustic energy source that consists of capacitors 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 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. Figure 1 shows boomer acquisition geometry for parts of 94CCT01 and all of 95CCT01. Changes in 94CCT01 acquisition geometry occurred several times and are recorded in the operations logbook. Table 1 displays acquisition parameters for both cruises. For more information about the acquisition equipment used, refer to the FACS equipment log for each cruise. Digital reproductions of all handwritten logbooks collected during each cruise are also provided.
The unprocessed seismic data are stored in SEG-Y format (Barry et al., 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. 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 email@example.com. Processed profiles can be viewed as GIF images from the Profiles page. Refer to the Software page for details about the processing and examples of the processing scripts.
Detailed information about the navigation systems used for each cruise can be found in Table 1 and the FACS equipment log for each cruise. To view the trackline maps and navigation files, and for more information about these items, see the Navigation page.
The original trace files were recorded in nonstandard ELICS format and later converted to SEG-Y format. The original trace files for 94CCT01 lines SL627_1, SL628_6, SL629_13, and SL630_15 and 95CCT01 lines TEXSB_3 - TEXSB_11 were divided into two or more trace files (e.g., SL627_1 became SL627_1a and SL627_1b) because the original total number of traces exceeded the maximum allowed by the processing system. Only the first 7,500 of 44,873 shots were recoverable from the original digital file for 94CCT01 line SL629_12. Navigation data are not available for the start of several 94CCT01 and 95CCT01 lines. No navigation was recorded for 95CCT01 line TEXSB_1.
The Disc Contents page is a diagram of the location of all files and folders mentioned in the text and provides links to some of these files and folders.
To access the information contained on this disc, use a web browser to open the file index.htm located at the top level of the disc. This report is divided into five sections: Navigation Data and Maps, Seismic Profiles, Field Activity Logs, 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 access to the Internet is available while viewing these documents.
Funding and/or support for this study were provided by the USGS Coastal and Marine Geology Program and the University of Texas Bureau of Economic Geology. At the time of data collection, author R. Morton was with the UT Bureau of Economic Geology. We thank R/V G.K. Gilbert Captains Keith A. Ludwig of the USGS in St. Petersburg, Florida, and J. Green of the NOAA Corps in Washington, DC, for their assistance in data collection. This document was improved by the reviews of Virginia H. Garrison and John T. Lisle of the USGS in St. Petersburg, Florida.
Barry, R.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, v. 40, p. 344-352. Also available online at: http://www.seg.org/publications/tech-stand.
Morton, R.A., Kindinger, J.L., Flocks, J.G., and Stewart, L.B., 1999, Climatic and eustatic control of Holocene nearshore parasequence development, southeastern Texas coast: Transactions Gulf Coast Association of Geological Societies, v. 49, p. 384-395.
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.