USGS
Read-me File
Archive of Datasonics SIS-1000 Chirp Subbottom Data
Collected During USGS Cruise MGNM 00014
Central South Carolina, 13-30 March 2000


U.S. Geological Survey Open-File Report 00-462

by Shawn V. Dadisman, Jenna C. Hill, William C. Schwab

U.S. Geological Survey, Woods Hole, MA 02543


INTRODUCTION


This CD-ROM (Compact Disc-Read Only Memory) has been produced in accordance with the ISO 9660 equivalent CD-ROM Standard and is therefore capable of being read on any computing platform that has appropriate CD-ROM driver software installed. Access to the data and information contained on this CD-ROM was developed using the HyperText Markup Language (HTML) utilized by the World Wide Web (WWW) project. Development of the CD-ROM documentation and user interface in HTML allows a user to access the information by using a variety of WWW information browsers (i.e. NCSA Mosaic, Netscape) to facilitate browsing and locating information and data. To access the information contained on this disk with a WWW client browser, open the file 'index.htm' at the top level directory of this CD-ROM with your selected browser. The HTML documentation is written utilizing some HTML 4.0 enhancements. The disk should be viewable by all WWW browsers but may not properly format on some older WWW browsers.

Also, some links to USGS collaborators and other agencies are available on this CD-ROM. These links are only accessible if access to the Internet is available during browsing of the CD-ROM.

The archived Chirp subbottom data are in standard Society of Exploration Geologists (SEG) SEG-Y format (Barry and others, 1975) and may be downloaded for processing with software such as Seismic Unix or SIOSEIS. The subbottom data were recorded on the ISIS data acquisition system in QMIPS format. Chirp subbottom channel extracted from raw QMIPS format sonar files and converted to 16-bit Int. SEG-Y format using the program QMIPSTOSEGY. Even though the data are in SEG-Y format, it is not the convential time series data (e.g. voltages or pressures), but rather instantaneous amplitude or envelope detected and therefore all of the amplitudes are positive (though not simply rectified). DOS and Microsoft Windows compatible software for plotting SEG-Y files (PLOTSEIS) and viewing SEG-Y headers (DUMPSEGY) is located in the PLOTSEIS directory. Processed chirp profiles (GIF images) may be viewed on this CD-ROM with your WWW browser.

BACKGROUND

In November 1999, the U. S. Geological Survey, in cooperation with Coastal Carolina University, began a program to produce geologic maps of the nearshore regime off northern South Carolina, utilizing high resolution sidescan sonar, interferometric (direct phase methods) swath bathymetry, and seismic subbottom profiling systems. The study areas extends from the ~7m isobath to about 10km offshore (water depths <12m). The goals of the investigation are to determine regional scale sand resource availability needed for planned beach nourishment programs, to investigate the roles that the inner shelf morphology and geologic framework play in the evolution of this coastal region, and to provide baseline geologic maps for use in proposed biologic habitat studies.

DIRECTORIES

Directory BIN:
Subdirectory PLOTSEIS:  This directory contains the DOS programs for plotting SEG-Y files and viewing SEG-Y headers.
Subdirectory SU: Contains the Seismic Unix scripts used to process and plot the chirp subbottom data and extract shot navigation from the SEG-Y headers
Directory HTMLDOCS: Contains the necessary HTML files and supporting graphics to allow the user access to the CD-ROM via any World Wide Web (WWW) browser.

Directory IMAGES:
Contains GIF and JPEG images that are used by HTML hyperlinks.

Directory MAPS:
This directory contains basemap and shot navigation themes. The data may be displayed with ARCVIEW version 3.1 or above, or ARCEXPLORER. You may need to copy the directories to disk and edit the .apr file in the PROJECT subdirectory to reflect the new directory paths.

Directory NAV:
Subdirectory RAWNAV: This directory contains raw DGPS navigation files as the data became available during the cruise.
Subdirectory SHOTNAV: Contains the shot navigation data that were collected during the cruise using a USGS differential GPS system.
Directory SEGY: Contains the Chirp SEG-Y format data. These data were collected using a Datasonics SIS-1000 Chirp subbottom profiler.  The SEG-Y data were logged on a Triton-Elics ISIS acquisition system. The SEG-Y format is documented in HTML.

Directory SEISIMAG:
Contains the GIF format files of the Chirp subbottom profiles generated with Seismic Unix.

DISCLAIMER
 
This Compact Disc-Read Only Memory (CD-ROM) 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 CD-ROM 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.

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., 1992a, DUMPSEGY V1.0: A program to examine the contents of SEG-Y disk-image seismic data; U.S. Geological Survey Open File 92-590.

Zihlman, F.N., 1992b, PLOTSEGY V1.0: A DOS graphics program to display SEG-Y disk-image seismic data; U.S. Geological Survey Open File 92-349A and 92-349B.