Seismic Signals Easier To Detect During COVID-19 Related Shut Down

Katie Ramirez
July 26, 2020

Earth vibrates naturally as a result of a variety of geologic processes, but human activities, including travel and industry, also produce vibrations that ripple through Earth's crust.

The researchers looked at seismic observations from 268 stations around the world.

According to the researchers, a visible effect of lockdowns was observed in the case of 185 stations, accompanied by a large-scale reduction in global noise, which began in China during early January and extended to Europe and other continents in March and April 2020.

A team of global researchers, which included scientists from Imperial College London, used devices known as seismometers to measure the noise caused by vibrations within the Earth. For this study, the team-76 researchers from 66 institutions in 27 countries led by Dr Thomas Lecocq of the Royal Observatory of Belgium-used 300 seismometers around the world to record their data.

Now an worldwide study involving Professor Martha Savage from Te Herenga Waka-Victoria University of Wellington's School of Geography, Environment, and Earth Sciences has shown there was also a significant measurable reduction in seismic noise. This research can help start a new area of study.

As many daily activities came to a halt during lockdown, the Earth itself became quiet, probably quieter than it has been since humans developed the technology to listen in.

Researchers who took part in this study revealed that human-caused seismic noise has reduced drastically over the past couple of months, and this could be for the first time that the planet is maintaining such silence in its humming due to human activities.

14-day quarantine for NI holidaymakers from Spain
Such quarantines are likely to put people off taking a holiday in "non-safe" countries. It follows an upsurge in coronavirus cases in a number of regions in Spain .

Although 2020 has not seen a reduction in earthquakes, the drop in human-caused seismic noise is unprecedented. "The noise level we observe during lockdowns lasted longer and was often quieter than the Christmas to New Year period", the researchers said.

Seismometers have very long recognised a fall in this shaking at evenings, at weekends and during holiday getaway durations - but this lull was significantly additional pronounced and extended. This new study is the first global study of the impact of this quiet period-coined the anthropause-on the solid Earth beneath our feet.

Researchers suggest the anthropause could help scientists develop new techniques for filtering out human-caused seismic noise and honing in on the kinds of seismic signals that might precede a natural disaster, like an quake, landslide or volcanic eruption.

Countries like Barbados, where lockdown coincided with the tourist season, saw a 50 per cent decrease in noise. The largest falls were in densely-populated areas such as NY and Singapore.

"Now we're using the same instruments, but the data is telling us about story of physical repercussions of this pandemic and their global nature".

The changes have also given us the opportunity to listen in to the Earth's natural vibrations without the distortions of human input. The study has shown the first evidence that previously concealed quake signals, especially during daytime, appeared much clearer on seismic sensors in urban areas during lockdown. The study's lead authors are based in Belgium, the United Kingdom, New Zealand and Mexico. The study's authors hope that their work will spawn further research on the seismic effects of lockdown.

With growing urbanization and increasing populations globally, more people will be living in geologically hazardous areas.

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