Notes on the CREWES Zoepplot Explorer Applet

- This applet is similar in function to the Zoeppritz Explorer, but is designed to be convenient for production of publishable figures.
- To use the applet, select whether the incident wave is P or S, and whether it originates in the upper or lower level. These choices may be changed at any time.
- Also select which coefficients you wish to have plotted. These may also be changed at any time. Only those for one type of incident wave may be displayed simultaneously.
- The plot shows how the reflection coefficients change with angle of incidence. To see how the coefficients change with properties of each medium, use the six scroll bars in the control panel to change the density and velocities of each layer. These may be fixed to particular values in the text fields, or interactively scanned over a range of values using the slider bars. Only four of these six variables are independent, one for the densities and three for the velocities. Accordingly one can use the drop down menus to select up to four density and velocity ratios as well. The slider bars generate ratios between 0 and 2, but other values can be accessed through the text fields. Note that you are not prevented from selecting properties corresponding to a negative Poisson's ratio.
- The results can be plotted either as a standard magnitude or in modified polar form. The magnitude is shown as positive or negative in order that the phase will always be zero below the first critical angle, and as continuous as possible beyond that. The phase itself is not plotted in this routine.
- The location of critical angles is indicated by vertical lines, which may be annotated with the value of the critical angle, and the relevant velocity conditions.
- The magnitude scale may be adjusted using the control panel. Angles may only be adjusted to integer numbers of degrees, and the incident angle must be between 0 and 90.

- A standard reference for the Zoeppritz equations and for the Aki-Richards approximation is Aki & Richards (1980) "Quantitative Seismology", vol. I, sec. 5.2.
- The source code for this applet is available to sponsors of CREWES (Consortium for Research in Elastic Wave Exploration Seismology, located at the University of Calgary).
- The Java applet was adapted by Chuck Ursenbach from the CREWES Zoeppritz Explorer
- Version history:
- The original Zoepplot Explorer was placed on the Internet in March, 2002.
- Further updates will be recorded at www.crewes.org.

Copyright 2002, CREWES, University of Calgary, All Rights Reserved