This is documentation on the dispersion calculation program called cal_disp, written by Jesse Fisher Lawrence (jlawrence@ucsd.edu). This code has a lot of problems. In this version, I donŐt know if the

1) Download:

2)Installation:

    A) Unpack the directory:
      :% tar -xvf DISP.tar
    B) Build the program:
      :% cd cal_disp
      cal_disp:% csh build.csh
    THIS SHOULD DO THE FOLLOWING:
      unpack the X11 interface (cal_disp:% tar -xvf X.tar)
      install the X11 interface (cal_disp/X:%: make -fMakefile_subs
      install the X11 test program (cal_disp/X:% make)
      install the cal_disp program (cal_disp:% make)
3) Run a test of the X11 PROGRAM:
    cal_disp:% ./testezxplot

4) To run a test of cal_disp:

    cal_disp:% csh run.EX.csh

How the program works:

    1) cal_disp reads in the files
    2) cal_disp sorts files by distance
    3) cal_disp cross-correlates all phases with each other
    4) cal_disp Fourier Transforms X-corrs into frequency domain
    5) cal_disp filters each period
    6) cal_disp Fourier Transforms the filtered x-corrs back to time domain
    7) cal_disp picks the time of x-corr maximum within a window
    8) cal_disp converts time to velocity
    9) cal_disp plots velocity v. period for each interstation pair with a an event-to-station back azimuth < 40 degrees different from the station-to-station back azimuth.
    10) The user can select (Turns red with left mouse button) or deselect (Turns blue with middle mouse button) which data are okay. Vertical lines indicate which periods are suitable based on distances between stations. Strictly choose only periods left of the first line. Loosely (for better signal to noise) choose only periods left of the second line. The auto button allows the user to select multiple phase velocities at once within a box (click once at the bottom left and again at the top right). To deselect with auto, click bottom left and top right with middle button. Hit next or last to proceed/redo to other station pairs.
    11) cal_disp calculates the back azimuth correction based on the different slownesses.
    12) cal_disp plots velocity v. backazimuth (red are selected values) for each period. There should not be a trend to these selected values. Ideally, but rarely they form a single horizontal line. Usually there is some scatter. Deselect any outliers. This calculates the new back azimuth correction (trends should be gone now). Press next or last to proceed or redo last period.
    13) cal_disp determines the new interstation distances traveled by a surface wave.
    14) cal_disp calculates the new velocity with backazimuth corrected distances.
    15) cal_disp plots velocity v. period for each interstation path for more quality control.
    16) cal_disp outputs dbase.1 which gives the results for all selected data.

Good luck!

Cheers,
-Jesse