Ocean waves colliding with Earth’s surface. The Earth produces a low frequency hum for years that puzzles scientists. It is hard to hear, but seismic instruments can detect it since decades. So we now know that the Earth does hum. French scientists have found that the constant background hum can be caused by waves colliding with each other. Their findings were published in Journal of Geophysical Research Letters. Earth scientists who specialize in propagation of seismic waves (seismologists), discovered that the Earth vibrates at very low frequencies even though there is no earthquake. Although the micro-seismic activity may not be detectable by humans, some animals like elephants or whales could sense it. The ocean waves colliding into one another creates the earth’s constant hum sound. People claim they hear the sound and experience sleeplessness, nausea, headaches, or a ‘kind of torture’. It sounds almost like a diesel car idled in the distance, but there is a lot of doubt about these claims. Many theories have been offered by seismologists over the years about the causes of the hum. These include submarine communication, mating fish and electromagnetic radiation. Many conspiracy theorists, as well as laymen, have also suggested their theories. These include secret military activity and beings from other universes trying to reach us. Ocean waves seem to be the culprit. Lucia Gualtieri and Eleonore Strutzmann, both from the Institut de Physique du Globe (all from France), created computer models of ocean and wind, which they then combined to create mini-seismic wave. The frequency of seismic waves generated by ocean waves is 13 up to 300 second. This refers to the time the ripple travels through the Earth’s crust before it disperses. The longer waves are responsible for most of Earth’s mysterious, hum-like sound. Ardhuin stated in an interview with Live Science that their result was an important step towards the understanding of noise and how it is transformed into a signal. Now Ardhuin, along with his colleagues, say that they can create more detailed maps of Earth’s interior. The seismic waves have yet to penetrate the Earth’s core. They could even reach the core. The authors suggested that by closely following the tracks of the waves, it may become possible to get a better 3-D view of Earth’s structures. Other sources of the hum include waves hitting the shore and water moving within mountains and at the bottom. Fabrice Ardhuin and Eleonore Stoutzmann, as well as Lucia Gualtieri. Geophysical Research Letters. Publication 10 February 2015. DOI: 10. 1002/2014GL062782.
Scientists now know the reason why planet Earth is humming
