A team led by Martha Deen at the Paris Institute of Earth Physics carried out a pioneering experiment and recorded the Earth's hum from deep under the sea.
"The Earth's hum is the permanent free oscillations of the Earth recorded in the absence of earthquakes," scientists wrote in the study published in Geophysical Research Letters.
The researchers of the Paris Institute of Earth Physics first gathered observation data from 57 seismometer stations collected during 11 months on the seafloor in the Indian Ocean east of Madagascar. After that, they painstakingly removed any sources of interference from identified sources, including the signals caused by ocean infragravity waves, seafloor currents and electronic glitches. What they had left was Earth's hum.
Besides hoping to discover the origin of Earth's hum, the team believes their research could help map the planet's interior, which is usually done using seismic data from earthquakes. Because the hum is constant, geologists wouldn't need to wait for earthquakes for data.