Three Months of Earth Vibrations, February-April 2020, Dublin, Ireland (acceleration 12000x)

The Earth’s natural vibrations show a sculptural quality, both visually and sonically: the continuous strata of the microseisms resemble cloud formations beyond the imaginary horizon line of the Earth’s hum below, revealing the constant, ever-changing movement of our planet’s crust. Earthquakes with their pops of P waves and whistles of S waves disrupt this movement like thunder and lightning in an electrical storm.

The stereo spectrogram was obtained from a long period seismogram (1 s to 450 s) recorded over a period of 88 days, from early February to late April, 2020. We can see three distinctive wavefields: the primary and secondary microseisms, and the range containing current-induced and infragravity waves. These are interspersed by earthquake events of varying magnitudes appearing as vertical lines. Most of these earthquakes were thousands of kilometres away. We can also observe a transition in weather, changing from a stormy February with high microseism amplitudes to a much calmer April.

This stereo track is a rendering of the 3 components of the motion of the ground recorded by the seismic station DSB of the Irish National Seismic Network, installed at a 236 m elevation south of Dublin, Ireland (53.25°N, 6.38°W). Bandpass filtering was applied in the audio domain to enhance the sonic experience: the amplitude in the frequency ranges of the microseisms and the infrasonic noise was reduced, and the amplitude in the frequency range between them, where earthquakes stand out, was slightly raised.