It seems far too easy for many people to think of the Earth as a fixed, lifeless ball of matter onto which we can project our will, but science clearly shows the Earth is quite ‘alive’ with many different natural processes and signs of ‘life.’ Plate tectonics are perhaps the most visible and dramatic of these, constantly reshaping the face of our planet in fiery displays of violent omnipotence. In recent years, scientists have detected a weak low-frequency vibration similar to seismic waves that seems independent of tectonic activity. A number of theories have been proposed for this “hum” including atmospheric disturbances to the rumble of massive underwater waves passing over the seafloor, but so far identifying a definitive source has eluded scientists because of the difficulty in locating and recording the hum.
To aid in the search for the source of the Earth’s deep hum, geophysicists from the Paris Institute of Earth Physics collected seismic data from 57 different monitoring stations on the bottom of the Indian Ocean off the east coast of Africa. The recordings were then processed using sophisticated software which allowed researchers to remove oceanic background noises and electronic glitches. For the first time, researchers were able to record and measure the low-frequency hum, but if you were hoping to be able to listen to the hum, you’re out of luck: the study found it peaks between between 2.9 and 4.5 millihertz, far below the lower human frequency threshold of around 20 hertz.
Their research has been published in Geophysical Research Letters. While it’s a little disappointing that the hum is far too low for humans to hear, knowing that there’s a strange frequency being given off by the center of the Earth is pretty rad in itself. It’s almost like we detected our planet’s pulse or heartbeat. It’s even better knowing that its cause is still ultimately a mystery. The authors of this study believe their data could help understand some of the processes occurring deep below the surface of the Earth, possibly even allowing them to map the Earth’s core down to 500 kilometers (300 miles). Those pesky Morlocks are soon gonna learn who’s boss.