You now have some basic knowledge about the nature and characteristics of mechanical waves: what they are, how they are measured, and the different ways in which longitudinal and transverse waves move through a medium as they transfer energy from one place to another.
Watch this animation to learn about seismic waves, which are the literally ground-shaking mechanical waves that occur during earthquakes.
Stop the animation at any time, watch it again, or read the transcript.
| Keyboard Shortcut | Action |
|---|---|
| Space | Pause/Play video playback |
| Enter | Pause/Play video playback |
| m | Mute/Unmute video volume |
| Up and Down arrows | Increase and decrease volume by 10% |
| Right and Left arrows | Seek forward or backward by 5 seconds |
| 0-9 | Fast seek to x% of the video. |
| f | Enter or exit fullscreen. (Note: To exit fullscreen in flash press the Esc key. |
| c | Press c to toggle captions on or off |
A great place to see longitudinal and transverse waves in action is during an earthquake. When energy builds up in the earth’s crust, it is released during an earthquake by waves of energy traveling through the solid ground. These waves, called seismic waves, are examples of longitudinal and transverse waves and transfer energy in predictable ways.
The first type of wave that occurs and travels faster are called primary or P-waves. P-waves are longitudinal, meaning they compress and stretch the earth to move the energy outward.
Then, slower moving secondary, or S-waves, follow. These are transverse waves and transfer energy by moving the earth’s layers up and down, while moving the energy outward.
Both of these longitudinal and transverse waves transfer energy over long distances and can be measured (wavelength, frequency, amplitude) to determine the location of the source of the earthquake.
Write a sentence or two describing each of the following terms: