Earthquake Distance Effects

As sound travels through the air or earthquake shaking travels through the ground, the waves lose energy. And so a band sounds louder close to the stage than further back and an earthquake feels stronger close to the fault than further away.

But there is another effect that changes the frequencies we hear and feel. High frequency waves lose energy more quickly than low frequency waves. So, the further you are from a band the more the bass sounds dominate what you hear. And the further you are from an earthquake the more the low frequency shaking dominates what you feel.

Below are two seismograms, or records of ground shaking, you can listen to. They come from the same earthquake but were recorded on two different seismometers at different distances from the earthquake. That's why they have different pitches. The volume has been adjusted to the same level so concentrate on the pitch to tell the difference. Click the sideways triangle (or play button) to hear the sound.

Seismometer One

Seismometer Two

Which seismometer was closer to the earthquake: One or Two?