The result is introduced in different countries, quarantine measures, fewer people use public and private transport, a large number of plants and factories stopped. Billions of people never leaving their homes, BBC reports.
All this has led to the reduction of vibrations on the surface of the crust. For the planet, the mass of which is six billion trillion tons, these changes may look minor, nevertheless they were recorded by seismographs.
First, the sharp decline noted by the researchers at the Royal Observatory in Belgium, saying that the fluctuations of the earth’s surface in the range of 1-20Hz (lower than the sound of the bass, like the sound of a great organ) became much weaker after the government introduced restrictive measures in the outbreak of coronavirus.
Similar changes were noted by scientists in other countries.
The silence in the mountains
Seismologists in Nepal noted a drastic reduction of vibrations on the surface. Fellow of the Paris Institute of Geophysics says that the effect in the city impressive, but scientists at the California Institute of technology called the changes “absolutely wild”.
The drop in the level of background noise caused by human activities is clearly seen in this illustration.
As the scientists explain, the seismographs are very sensitive devices fixing external vibrations: they respond not only to earthquakes but also to fluctuations at the Earth’s surface caused by other sources — natural or man-made.
So, they react to the vibrations produced by cars, industry, aircraft, construction work or the usual movement of people moving groups or singly.
Simply put, life in the city is recorded at a nearby seismic station as background noise. The sensitivity of the instruments is so high that the effects of imposed quarantine measures immediately reflected on their records.
In the illustration above — the testimony of one of the 22 seismographs installed in secondary schools of Nepal in the framework of the project “Seismology for students.”
Changes in the graph show the difference between the background noise in the range of 4-14 Hz in the daytime and at night. The black dotted line marks the date of the end of school exams in grades 1-9, after which starts to happen decline in fluctuations. Pink dotted line is the day when Nepal was declared a quarantine.
Noticeable drop in noise level indicates that in this region froze a large part of human activity, including at night — indicating that the reduction in transport and production activity.
Clean air, quiet oceans
Coronavirus and how it reacts humanity, not only affects all of us, but on nature and the ecology of the planet.
Satellite observations show that air pollution emissions of nitrogen dioxide (produced by passenger cars, buses, trucks and power plants) has decreased dramatically.
In addition, the world became quiet — and not just on the surface, but under water. Researchers studying the level of noise in cities or in the depths of the ocean say that this level is significantly decreased.
More clear signals
The new data do not indicate that the crust ceased to fluctuate. But the weakening of the oscillations in a particular frequency range due to the fact that people sit at home, helping scientists to understand how to operate these fluctuations.
What people do can be viewed as a kind of background noise that does not allow to exactly understand how it behaves in the Earth and why.
“We are now able to receive signals with less interference, allowing you to squeeze some more information,” says Andy Frassetto of the Seismological Institute of the state of Washington.
The decrease in the intensity of human-caused vibrations of the earth made a particularly interesting effect in Brussels. Thanks to the lockdown, the seismologists got the ability to detect small earthquakes and other seismic phenomena that remained unnoticed for devices placed in certain places.
Take, for example, the seismic station in Brussels. Geologist and seismologist Thomas Lecoq of the Royal Observatory of Brussels, first drew attention to this phenomenon explains that in usual time, the seismic station almost useless.
Such stations are usually built in the side of the densely populated areas, where produce people the noise complicates the detection of weak vibrations in the earth’s crust. But the station in Brussels was built over a hundred years ago and since then has been absorbed by the sprawling city.
From the daily noise of the big city of Brussels, the station is usually incapable to detect small seismic events. Instead, scientists collect data from another station, whose measuring instruments are located in a specially drilled mine at a considerable depth.
“However, at the moment due to the lull in the city station surface works almost as well as the one under the earth,” the scientist said.
Some researchers even managed to determine exactly what caused the reduction of background noise in their region. Stephen Hicks, Imperial College London, connects it with the fall of traffic on the M4 motorway linking London with Wales.
“Quite clearly that the buildup of noise at dawn, now is not expressed so sharply as in previous weeks. I believe that this is due to the fact that the traffic during rush hour is not as busy now — fewer people driving to work and carrying children to school”, — explained the scientist.
Something similar was observed in the past. In different seasons, and at different times of the day, people behave differently: in winter, for example, often sit at home, and in the summer moved more actively.
At night the background noise level is reduced; in addition, such a decline occurs regularly on weekends and public holidays.
But the current noise reduction much longer — for weeks and months, not day or more, as it usually happens during Christmas in Christian countries.
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