Listening to Earthquakes
Created by Andy Michael, USGS, and Daniel Ross, 12 year old USGS Volunteer for Science.
When we listen to music we hear a wide range of sound frequencies or notes. When we feel an earthquake we feel a wide range of frequencies but unlike music the notes are less distinct. People describing what they felt during an earthquake may call it a "sharp jolt" or a "rolling motion." The sharp jolt is due to high frequencies while the rolling motion is due to low frequencies. What you feel during an earthquake is a product of the earthquake itself, how far you are from the earthquake, and the types of rocks between you and the earthquake. To learn about this we will convert the shaking during earthquakes to sound and then listen to the sounds.
Converting Shaking to SoundWhen a loudspeaker produces sound it shakes. During an earthquake the ground shakes. To convert the earthquake shaking to sound we make the loudspeaker shake the same way the ground did. But, if we really did that the sound would be too low for people to hear. So, we speed things up so that the loudspeaker moves back and forth much faster than the ground did and then we can hear it.
Tips for listeningThe sound files on these pages are in .wav format. If your browser can't play them back, you will need to install a plugin that will do this.
The sounds on these pages require a good loudspeaker. If your computer doesn't have good speakers (a subwoofer is best) then try using a pair of earphones.