RT @SeismoSue@twitter.com

You know about P waves & S waves, but did you know the P wave is basically a sound wave traveling through the earth, & they can couple into the air? Humans only hear >30 Hz waves & that energy attenuates quickly, so audible quakes are only a thing if the quake is close.

🐦🔗: https://twitter.com/SeismoSue/status/1350500385111171072