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Seismologists know that unusual circumstances of confinement will only exist for a short period
The UK has not been shaking as much since entering the Covid blockade.
Seismometer stations, which are normally used to record earthquakes, have detected a large drop in ground vibrations related to human activity.
Scientists at Imperial College London say this background hum is now half of what it would normally be.
The unprecedented seismic silence, a phenomenon reflected in other countries, could offer a unique opportunity to study the interior of the Earth.
“You would have to go back decades to see noise levels like this,” said Dr. Stephen Hicks of Imperial. “I often had quiet moments in the evenings or on weekends, but not continuously, for weeks,” he told BBC News.
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Human activity (cars, trucks, trains, industry, footfall, etc.) appears on seismometers in a frequency band of 5 to 15 hertz.
Dr. Hicks used data from 127 instruments spread across Britain to map signal evolution from mid-January to the present.
It was based in part on high-fidelity science stations operated by the British Geological Survey (BGS), but also on a distributed network of citizen science seismometers incorporating Raspberry-Pi mini computers.
The vibrations detected in both instrument sets are seen to drop dramatically after Prime Minister Boris Johnson orders the closure of Britain on March 23.
“Seismic noise reduction should help us see the signals from earthquakes that are normally buried in noise,” said Dr. Brian Baptie, head of seismology at BGS.
“This could allow us to detect more small earthquakes or to see the low-amplitude parts of ground movements caused by larger earthquakes farther away.”
Scientists around the world are cooperating to exploit the research potential.
Dr. Thomas Lecocq, from the Royal Observatory of Belgium, started a community that operates on the Slack communications platform and calls itself “Lockism Seismology”.
The group has more than 85 members in more than 30 different countries.
Dr. Lecocq said very low magnitude earthquakes were being investigated, as was the activity of volcanoes.
Researchers at Mount Etna in Sicily are trying to hear the quiet hum of the mountain, hoping to learn something new about their behavior, something that could be useful in future monitoring.
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S.L.HICKS
Dr. Hicks’ analysis used data from a network of citizen science seismometers
Dr. Baptie is cautious, however.
“In theory, [the reduction in seismic noise] It could lead to new ideas, since much of our understanding of Earth’s internal structure comes from earthquake observations.
“However, this is generally based on observations over long periods of time, while the time window in which our detection capacity could be improved is likely to be relatively short.”
Dr Hicks added: “It is going to be interesting to see how the noise goes up again and how that varies across the UK. I suspect London sensors became quieter before entering the blockade, relatively speaking compared to your baseline. ”
“We will write a short document just to say that we have this cool observation and that we have seen this seismic noise reaction moving around the world, starting in China. Then we will discuss what we could do with in the future.”
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