U.S. Geological Survey Data Series 254
1ETI, 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 - St. Petersburg
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).
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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 disc 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.
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 Services at 1-888-ASK-USGS.
This disc is readable on any computing platform that has standard DVD driver software installed. The minimum software requirements are a Web browser, Adobe 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. Note: The only supported Web browsers that properly display all features of the interactive profiles are Internet Explorer 6 for Windows and Firefox 1.5 for all platforms.
In May of 2006, the U.S. Geological Survey conducted geophysical surveys offshore of Siesta Key, Florida, as part of the USGS Florida Shelf Habitat (FLaSH) Mapping Project (http://coastal.er.usgs.gov/flash). This report serves as an archive of unprocessed digital Chirp seismic reflection data, trackline maps, navigation files, GIS files, Field Activity Collection System (FACS) logs, observer's logbook, and formal FGDC metadata. Gained digital images of the seismic profiles are also 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 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.
The USGS Florida Integrated Science Center (FISC) - St. Petersburg assigns a unique identifier to each cruise or field activity. For example, 06FSH01 tells us the data were collected in 2006 for the Florida Shelf Habitat (FLaSH) Mapping 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 field activity ID.
All Chirp systems use a signal of continuously varying frequency; however, the Chirp system used during this survey produces a high resolution, shallow penetration (less then 50 ms) profile image beneath the seafloor. The sound source and receiver is a towfish, which is typically towed 2-5 m above the seafloor. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), detected by a receiver, and recorded by a PC-based seismic acquisition system. This process is repeated at timed intervals (for example, 0.125 s) and recorded for specific intervals of time (for example, 50 ms). In this way, a two-dimensional vertical image of the shallow geologic structure beneath the ship track is produced. Figure 1 displays acquisition geometry. Refer to table 1 for a summary of acquisition parameters. See the digital FACS equipment log (11 KB) for details about the acquisition equipment used. Table 2 lists trackline statistics. Scanned images of the handwritten FACS logs and handwritten science logbook (12 MB) are also provided as PDF files.
The unprocessed seismic data are stored in SEG-Y format (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 download instructions. The printable profiles provided here are GIF images that were gained using Seismic Unix software. Refer to the Software page for details about the processing and examples of the processing scripts. The processed SEG-Y data were then exported to Chesapeake Technology, Inc. (CTI) SonarWeb software to produce an interactive version of the profile that allows the user to obtain a geographic location and depth from the profile for a cursor position. This information is displayed in the status bar of the browser. Note: The only supported Web browsers that properly display all features of the interactive profiles are Internet Explorer 6 for Windows and Firefox 1.5 for all platforms. For all browsers, the status bar and JavaScript must be enabled. Firefox also requires "Change status bar text" to be checked under Advanced JavaScript Settings. Caution– use of other browsers may result in spurious or no information given in the status window. The printable and interactive profiles can be viewed from the Profiles page or from links located on the Survey Area Map page.
Detailed information about the navigation systems used can be found in table 1 and the FACS equipment log (11 KB). To view the trackline maps and navigation files, and for more information about these items, see the Navigation page.
NOTE: No navigation was written to the SEG-Y headers for most of line 06c01; therefore, no line navigation map, interactive profile, or trackline statistics could be created for this line. However, navigation was collected for a coincident sidescan sonar trackline. This sidescan sonar navigation was merged with the Chirp shotpoints by the recorded time to create the reconstructed tracklines found on the location and survey area maps. Incidentally, the sidescan sonar line started at shotpoint 1500, so no navigation exists for the first 1499 shots of line 06c01.
The Disc Contents page is a diagram of the location of all files and folders contained on this disc and provides links to these files and folders.
To access the information contained on this disc, use a Web browser to open the file index.html. 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. Note: The only supported Web browsers that properly display all features of the interactive profiles are Internet Explorer 6 for Windows and Firefox 1.5 for all platforms
Funding for this study was provided by the USGS Coastal and Marine Geology Program. We thank R/V G.K. Gilbert captain Rich Young of the USGS in St. Petersburg, Florida for his assistance in data collection. This document was improved by the reviews of Ellen Raabe (USGS) and Kate Ciembronowicz (ETI) at the FISC - St. Petersburg, Florida.
Barry, R.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 online at http://www.seg.org/publications/tech-stand.
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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