Science & Technology

What causes the Earth's mysterious hum ?

By T.K. Randall
April 16, 2015

Image Credit: (PD) NASA via Wikimedia Commons While it has long been known that seismic events can cause the planet to resonate for up to several months, evidence has also been found of a second, more subtle type of vibration that seems to occur all the time even when there are no earthquakes.

This microseismic activity is too faint for humans to pick up but now researchers investigating the cause of the phenomenon have discovered that ocean waves may be responsible.

Through the use of computer models simulating the movements of the wind and tides the scientists were able to determine that colliding ocean waves produce seismic waves that can take up to 13 seconds to complete one oscillation.Slower waves however can take a lot longer - up to 300 seconds - and it is these that are thought to cause the mysterious hum due to the pressure of the water being dragged across the seafloor.

"I think our result is an important step in the transformation of mysterious noise into an understood signal," said lead study author and oceanographer Fabrice Ardhuin.

Because these waves can penetrate deep in to the Earth's mantle it is also hoped that a complete understanding of this phenomenon could help scientists learn more about the planet's interior.

Source: Live Science

Tags: Earth.Hum, Earthquakes