The Earth is humming at very low frequencies, or so do scientists claim after having recorded the mysterious signal in the ocean floor. While there are numerous theories as to why the Earth emits these strange sounds, researchers have yet to pinpoint a viable reason.
Previous theories have stated that the Earth’s atmospheric turbulence was responsible for the hum or even how our planet regularly expands and contracts.
This phenomenon has baffled scientists since the late 50s, however, evidence of the hum was only brought to attention in 1998. The new study suggests Earth’s vibration to originate, at least in part, from the ocean waves.
“The Earth is ringing like a bell all the time. (The primary cause of the Earth’s hum) is ocean waves banging on the sea floor pretty much all the way around the Earth.” Said Spahr Webb, a seismologist at Columbia University.
A team of European geophysicists installed seismometers on the floor of the Indian Ocean to register the noise. They needed to gather data from several of these devices to filter out any white noise that was picked up. The feat itself has been tricky to do in the past, considering the ocean’s motion coupled with background noise from earthquakes and other ocean sounds.
Earth vibrates or oscillates at a frequency of between 2.9 and 4.5 millihertz, which is thousands of times lower than what humans can hear. The waves crashing in opposite directions sometimes intersect, which send vibrations deep into the Earth’s crust. Even a wave crashing on a coast can send ripples over the sea floor which contributes to the hum.
The origin of the Earth’s hum has yet to be established, however, the ultralow frequencies are a significant breakthrough which will hopefully determine the source of the noise. The study was published in the Geophysical Research Letters journal.
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