Notes on the CREWES Zoepplot Explorer
- 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
- 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