The ocean waves cause the Earth beneath our feet to let out a constant hum of its own melody, or so say a team of French scientists whose work has been published in the journal Geophysical Research Letters. So, how do the waves inspire the Earth to unceasingly hum a lullaby?
The Earth is known to vibrate constantly, even at times of no earthquake. We do not feel the vibrating hum, but it is indeed existent. The humming of the Earth has been traced back to a constant vibration of low frequency that spreads throughout the entire planet at all times. The phenomenon can be compared to a ringing sound. The ocean waves are said to be behind this microseismic occurrence. How is this brought about?
According to the hypothesis put forth by the French researchers, two kinds of waves act together to cause the constant humming: deep ocean waves spreading along the seafloor, and colliding ocean waves. These constitute two types of mechanisms. The researchers merged both of them into one model in an attempt to prove or disprove their theory. They found that colliding ocean waves would trigger seismic waves taking 13 seconds or less to make one complete ripple, while the second type of waves would generate seismic waves with longer frequency ranges. The findings suggested that the longer waves contributes to the ringing to a larger extent.
“I think our result is an important step in the transformation of mysterious noise into an understood signal,” said lead researcher, Fabrice Ardhuin, an oceanographer at the French Research Institute for Exploitation of the Sea.
It is to be noted that the results do not imply that the microseismic activity is caused solely by these types of waves. Those waves along shorelines might also be responsible to the humming. Other waves generated in underwater mountains could also be playing a certain role. The new study is more of an invitation for additional research.
A more in-depth understanding of the ‘Earth song’ could provide invaluable information pertaining to the creation of better maps of the Earth’s insides. This is so because seismic waves could be travelling into the depths of the earth, till its mantle and into its core. The Earth’s interior is much of a mystery to us, and research focused on this hum could give us a more detailed structure of what lies under our feet.