How can we model seismic waves in the classroom?
How can I get across the idea in a classroom activity using no props?
Given the motion behavior for the human wave, can you guess which wave, P or S will be faster?Can I model a liquid core using this method?
Roger Groom* has his class model P and S seismic waves through solids and liquids.
This is a DRAFT version to be updated. Caveats include: The arms-over-shoulders method is a far better analogy to hand-holding method for best physics as noted in subtitles in the video. With hand holding, energy propagates down the line due to internal energy from the particles (the brain telling the other arm to raise) rather than transferring from one particle to the next as in the arms-over-shoulders method that happens automatically.
NOTES FOR TEACHING:
This demo is a simplified model of natural phenomena. As such it is especially important to emphasize both the strengths and weaknesses of the model to students. Such an explicit discussion helps students focus on the model as a conceptual representations rather than a concrete copy of reality. See Key points below.
*Mount Tabor Middle School, Portland OR
Points to address with students:
Seismic waves travel through the earth to a single seismic station. Scale and movement of the seismic station are greatly exaggerated to depict the relative motion recorded by the seismogram as P, S, and surface waves arrive.
We use exaggerated motion of a building (seismic station) to show how the ground moves during an earthquake, and why it is important to measure seismic waves using 3 components: vertical, N-S, and E-W. Before showing an actual distant earthquake, we break down the three axes of movement to clarify the 3 seismograms.
A cow and a tree in this narrated cartoon for fun and to emphasize that seismic waves traveling away from an earthquake occur everywhere, not just at seismic stations A, B, C, and D. A person would feel a large earthquake only at station A near the epicenter. Stations B, C, D, and the cow are too far from the earthquake to feel the seismic waves though sensitive equipment records their arrival.
This companion to the animation "Four-Station Seismograph network" shows the arrival of seismic waves through select wave paths through the Earth (P and S waves) and over the surface of the Earth. The movement at distant stations occurs at a microscopic scale. While that doesn't result in noticeable movements of the buildings, the arrivals are recorded on sensitive seismometers.
The Earth has 3 main layers based on chemical composition: crust, mantle, and core. Other layers are defined by physical characteristics due to pressure and temperature changes. This animation tells how the layers were discovered, what the layers are, and a bit about how the crust differs from the tectonic (lithospheric) plates, a distinction confused by many.
Video lecture on wave propagation and speeds of three fundamental kinds of seismic waves.
A video demonstration of how a slinky can be a good model for illustrating P & S seismic waves movement.
Earthquakes create seismic waves that travel through the Earth. By analyzing these seismic waves, seismologists can explore the Earth's deep interior. This fact sheet uses data from the 1994 magnitude 6.9 earthquake near Northridge, California to illustrate both this process and Earth's interior structure.
This poster combines a visualization of ground motion resulting from the February 21, 2008 M 6.0 earthquake that occurred near Wells, NV, with the image of a faucet to illustrate a classic Earth science functional analogy: "Seismic waves radiate outward from an earthquake's epicenter like ripples on water".
Seismic waves from earthquakes ricochet throughout Earth's interior and are recorded at geophysical observatories around the world. The paths of some of those seismic waves and the ground motion that they caused are used by seismologists to illuminate Earth's deep interior.
Remember the “stadium wave,” when one person stands and raises his hands in the air and the motion is translated completely around the arena? This simple kinesthetic demonstration uses a similar principal by sending seismic waves through a line of people to illustrate the difference between P waves and S waves propogating through various materials. Lined up shoulder-to-shoulder, students to "become" the material that P and S waves travel through so that once "performed," the principles of seismic waves will not be easily forgotten.
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