It may be lower to ‘acoustic resonance’, the reputation for a phenomenon which sees one vibrating object or system make another vibrate.
Earth may produce ‘permanent free oscillations’ which aren’t brought on by earthquakes or any other seismic activity.
The hum is about 10,000 occasions underneath the limits of human hearing, meanings it’s totally inaudible.
An effort to identify this hum was initially produced in 1959 nevertheless its existence was just finally proven in 1998.
This really is significant because two-thirds in our planet is included by water.