Scientists capture Earth’s “hum” on ocean floor - GeoSpace - AGU Blogosphere (6/12/17)
Scientists have long known earthquakes can cause the Earth to vibrate for extended periods of time. However, in 1998 a research team found the Earth also constantly generates a low-frequency vibrational signal in the absence of earthquakes.
Since then, seismologists have proposed different theories to explain the existence of this continuous vibration, from atmospheric disturbances to ocean waves moving over the sea floor. They’ve also measured the vibration using seismometers on land, but had not yet successfully measured it at the sea floor, which could help scientists better quantify the sources of the vibrations.
Now, using seismic instruments on the bottom of the ocean, researchers have successfully quantified Earth’s vibrational “hum”. A new study published in Geophysical Research Letters, a journal of the American Geophysical Union, determined at the ocean bottom the frequencies at which the Earth naturally vibrates, and confirmed the viability of using ocean instruments to study the hum.
Hélas pour nous (et pour @intempestive, notamment) à 10 oscillations par heure, peu d’espoir d’entendre directement les soupirs de Gaïa… Sauf à les transformer en accélérant la bande son. C’est, évidemment, suggéré dans les commentaires…
The study determined Earth’s natural vibration peaks at several frequencies between 2.9 and 4.5 millihertz. These vibrations can’t be heard by people because they are approximately 10,000 times smaller than the lower hearing threshold of the human ear, which is 20 hertz.