Waves Through Earth: Interactive Online Mac and PC
This activity was selected for the On the Cutting Edge Reviewed Teaching Collection
This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are
- Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
- Completeness of the ActivitySheet web page
For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Sep 18, 2006
This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.
- P and S rays superimposed on the four-region model;
- Table of data for P and S wave velocities;
- Graph of "data" and Model for P and S waves;
- Help and instructions.
- Difference in P and S wave velocity;
- P wave and S wave shadows;
- That S wave velocity must be zero for outer core to match observations;
- How to adjust model parameters to match observations.
Context for Use
Description and Teaching Materials
Seismic wave Speed Through Earth (more info) has the complete activity. Click and drag the velocity lines at the top and bottom of each layer in the graph of Velocity vs. Depth to match the observed travel-time curves of times tab. [click image to enlarge]
Teaching Notes and Tips
Completion of the activity can easily be assessed by having students fill out the table provided here (taken from model tab of Applet) once they get their best fit. [click image to enlarge]
Examples of other appropriate questions are:
- What is the angular extent of the P wave shadow after wave speeds have been adjusted for best fit to data?
- Describe in your own words how wave speed changes with increasing depth towards Earth's center.
- Which waves travel faster, P or S waves?
- Perform a Google search (http://www.google.com) of P-wave and S-waves and in your own words describe what they are.
References and Resources
The Virtual Physics Laboratory of The Department of Physics and Astronomy at Northwestern University has a good animation of P (longitudinal) and S (transverse)waves.