Seismic Unix Scripts Seismic Unix (SU) is a public domain seismic processing software package written and maintained by the Center for Wave Phenomena at the Colorado School of Mines in Golden, CO. The Web site for SU is http://www.cwp.mines.edu/cwpcodes. SU is compatible with Unix, Linux, and Mac OS X operating systems. The SU scripts provided on this disc and listed below were run on a Mac OS X workstation. These SU scripts and other needed files and software are located in the TAR file chirp.tar, which can be found in the su subfolder of the software folder located at the top level of this disc. These scripts are provided as examples only. They may need to be modified to run on another system. They also require the use of shareware programs such as ImageMagick and Ghostscript. The example SU scripts provided here will allow the user to strip off navigation fixes from the SEG-Y headers, along with a fix for every 1,000 shots, and produce a gained GIF image of each profile. These images can then be displayed using a variety of shareware programs such as ImageMagick (Unix, Linux, and Mac OS X) or a Web browser. To use the scripts provided here you must first install SU on a Unix, Linux, or Mac OS X system. The scripts require that the following four subdirectories be created (all at the same hierarchical level) before the scripts are run: 1. su, 2. segy, 3. seisimag, and 4. nav. If you untar the chirp.tar file, these subdirectories will be created for you. The SU scripts and all associated files (see below) should be placed in the su subdirectory. You may copy the SEG-Y files in the segy subdirectory or leave them on the disc. The GIF images will be written to the seisimag subdirectory, and the navigation data to the nav subdirectory. Provided below is a step-by-step explanation of the processing sequence and example parameters required by each script. For more information please refer to the SU documentation provided on the Web or locally if Seismic Unix is installed on the computer. These scripts are provided as examples only because there are many differences between Unix, Linux, and Mac OS X systems. Step 1. Untar the chirp.tar file (tar xvf chirp.tar), and it will create the four subdirectories and write the scripts to the su subdirectory. Step 2. Make sure the permissions for all files in the su subdirectory have been set to allow execution (chmod +x scriptname). These first two steps do not need to be repeated. Step 3. Run readll_chirp. Change the first line of the script to point to the directory location of the SEG-Y file (absolute or relative path). This script requires the following information (using command line inputs), in this order, on one line, and separated by spaces: $1= the file name (without the .sgy extension, which is case sensitive) Example 1: readll_chirp 10c01 This script will create an SU file named filename.su in the su directory. It will also create trackline navigation files called filename.txt (unique navigtion fixes for that trackline) and sfilename.txt (navigation fixes for every 1,000th shot along the trackline) in the nav directory. Step 4. Run chirp_plot. This script requires the following information, in this order, on one line, and separated by spaces: $1= tmin (time minimum for this data set is 0) $2= tmax (time maximum in seconds, for example, 0.050) $3= the SU file name (without the .su extension) $4= the height of the plot in inches (try 8) $5= the pclip value (try 98 - higher is lighter, lower is darker) Example 1: chirp_plot 0 0.050 10c01 8 98 This script will create gained, printable profile and thumbnail .gif images in the seisimag directory. It will also write all script related processing parameters to the history file located within the su directory. Repeat steps 3 and 4 for each data file. Step 5. View the seismic profile written to the seisimag subdirectory using a Web browser or ImageMagick for GIF images, or Ghostview for PostScript files. The files listed below are used by the SU script chirp_plot. These files will be extracted from the chirp.tar file and placed in the su subdirectory. gsgifscript - needed by makegif3 to convert the PostScript image to a GIF image history - keeps a record of the data processed and parameters used landscape.ps - converts the PostScript plot to a landscape display direction makegif3 - converts the PostScript image to a GIF image Note: These are c-shell scripts. Make sure that your .cshrc file has been modified as per the SU installation instructions. For example, on our system you must add the location of /opt/cwp/bin to the set path statement. Also, a setenv statement must read setenv CWPROOT/opt/cwp.