Earth makes a tiny seismic rumble every 26 seconds. Why is Earth pulsating every 26 seconds, and why can’t scientists explain it after 60 years? Related Story This Unlimited Energy Could Power Earth ForeverSome researchers think the pulse has a kind of prosaic cause. It’s not impossible that just one shape of continental shelf “drum” would create the right harmonic bang to rattle the Earth. And there’s a similar volcanic microseism that’s already well documented in Japan.