Seismic ring of the Earth

Just like a bell, the earth rings with natural frequencies when it is hit.

This recording is the seismic ring of the earth recorded for more than two months, right after the giant Sumatra-Andaman earthquake (magnitude 9.1, 26th Dec 2004), which created the devastating tsunami around the Indian Ocean.

The seismic waves are recorded at a seismic station in East Australia (Canberra) and sped up 400,000 times to audible range: 1 second of audio is about 5 days in reality.

You can hear the harmonic ring of the whole Earth, with a range of natural frequencies between 0.1-1mHz. A lots of small harmonic clicks can also be heard, almost sounding like a tight string being plucked: they are the aftershocks of the giant earthquake, that keep hitting the Earth-bell — although much more softly, like a smaller hammer.

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A great visualization of this phenomenon: https://jbrussell.github.io/outreach/normal_modes/

Sonification method:
A seismometer (seismic station) records ground velocity in time. This data can be turned into sound by speeding it up, as ground motion is usually in infrasonic frequencies. Most seismic data can be freely (although not easily) downloaded from https://service.iris.edu/fdsnws/dataselect/1/.