People make noise – a lot of it, but not in the way you may think. Feet slap against the sidewalks and roads. Cars rumble along the streets. Planes roar overhead. Since world leaders have urged the population to stay at home and socially distance to slow the spread of the COVID-19 pandemic, our daily hum of life has quieted.
What detects the noises we took for granted are seismometers, and it is usually classified as seismic noise. Seismologists across the globe have noticed these changes, particularly in densely populated cities of Switzerland, Spain, Italy, the United Kingdom, China, Nepal, the United States, New Zealand, and more.
According to Dr. Ilias Papadopoulos, the Engineering Seismologist at the University of the West Indies Seismic Research Centre, “Comparing the level of noise-induced by anthropogenic activity to our seismological stations, I can report that Trinidad is no exception.”
The magnitude of the change depends on many factors, including population density and nearby industrial activity. Even the position of a seismometer within a city can influence the size of the lull.
By comparing the seismometer’s noise levels affected by human activity, which is seen at higher frequencies (above 5 hertz), from April 10th, 2019, and April 19th, 2020, located at Woodbrook, Port of Spain, the spikes of life on the frequency chart is notably reduced. It is worth noting, according to Dr. Papadopoulos, “the lower frequencies where the spectrum is affected by sea tides and geological processes, it remains almost unchanged.”
Though lulls in seismic noise are not unusual, this seismic quiet on a global scale is another unprecedented situation arising out of COVID-19. One of the benefits of this global quiet is that seismologists may have better overall data to detect faint or distant earthquakes that would have previously could have been missed. A good parallel for this would be operating in a quieter room.