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

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.

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.

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.