Zoeppritz Phase Plotter

Quick Links


You will need to have the Java runtime environment (JRE) installed on your computer in order to use this software. As of Java Version 7 Update 51, you will also need to add https://www.crewes.org to the Java Exception Site List. This has been tested in Windows 10 using Microsoft Internet Explorer, Microsoft Edge and Mozilla Firefox.

To start the Zoeppritz Magnitude Plotter click on the 'Launch' button above.

  • This Plotter is similar in function to the Zoeppritz Explorer, but is designed to be convenient for production of publishable figures of Zoeppritz coefficient phases.
  • To use the Plotter, 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 plot phases for. These may also be changed at any time. Only those for one type of incident wave may be displayed simultaneously.

Version History

The Java code was adapted by Chuck Ursenbach from the CREWES Zoeppritz Explorer. The original Zoeppritz Phase Plotter was placed on the Internet in March, 2002.

Technical Notes

  • 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.
  • Using a checkbox, the phase can either be plotted as a continuous function or constrained to lie in the interval [-π:π].
  • 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 scales 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 degrees.


  1. Aki & Richards (1980) "Quantitative Seismology", vol. I, sec. 5.2.

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