Seismic Waves (Earthquake Waves)
What are the different types of Seismic Waves?
There are three main types of waves.
- Secondary Waves (S Waves) – These waves are recorded by the seismograph second. These waves shake the Earth perpendicular to the direction that they move in. They move up and down. Secondary waves cannot travel through Earth’s liquid outer core.
- Surface Waves – These waves are recorded by the Seismograph last. These waves can only move through the surface of the Earth, unlike P and S waves that can move through the inside.
How Fast can Seismic Waves Travel?
Seismic Waves are pretty darn fast! When traveling through the air, P Waves can move at about 330 m/s*. In water, they can move at about 1450 m/s. When they travel through granite, they can move at 5000 m/s! That’s fast!
Because S waves cannot travel through liquids, they move at about 60% of the speed that P waves do through any material. With that said, even though P waves move faster than S waves, they are still very powerful.
(*Meters per second)
What is a Seismograph? How does it work?
A Seismograph detects and measures the movement of the Earth. A weight is suspended in a way that lets it detect when the ground moves, and it records the movement for us. Seismologists will use the data recorded by the Seismograph to detect earthquakes. It can also detect volcanic activity, and other similar things.
Other Great Resources:
Seismic Waves – Colorado.edu – https://www.colorado.edu/physics/phys2900/homepages/Marianne.Hogan/waves.htm
How a Seismograph Works – KidsKnowIt –
Seismology – SimpleWikipedia – https://simple.wikipedia.org/wiki/Seismology