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But now, due to the COVID-19 pandemic and operational restrictions still very active in many states, the most dramatic reduction in that anthropogenic seismic noise has been observed in the entire history of observations.
“This quiet period is probably the longest and strongest reduction in man-made seismic noise since we began to observe the entire planet in detail with an extensive network of seismometers.” Our study uniquely highlights how human activities affect Earth’s hard crust and can help us understand more clearly than ever how human-induced noise differs from natural noise, “said Stephen Hicks, a seismologist at Imperial College London (UK).
This quiet period is probably the longest and strongest reduction in man-made seismic noise since we began observing the entire planet in detail with an extensive network of seismometers.
Earthquakes are continuously recorded. Hundreds of seismic vibration monitoring stations located around the world even help us predict and understand volcanic and earthquake activity, as well as describe changes in water levels in the oceans and even changes in atmospheric pressure.
But all these signals must be distinguished from the general noise caused by human activity, which, on a planetary scale, never ceases substantially. It is true that at some specific time there is a significant reduction in people’s noise, let’s say that weekends are usually quieter. And festive periods: Christmas, New Year, Chinese New Year. But even at that moment, the noise of the people does not disappear.
People noise has not disappeared even now, during the pandemic. But its decline is stronger than ever: noise has been suppressed by about 50 percent, and that decline has been going on for months.
The study is based on data collected over many months, including 2020. In May. The data was collected by 268 seismic activity monitoring stations located in 117 countries around the world. When individual countries announced restrictions on international travel and domestic business activities, first in China, in January, and then in Europe, and eventually around the world, to curb the spread of COVID-19 infection, a clear trend emerged. .
Scanpix Photo / World Seismometer Design Map
185 of all seismic stations recorded significant attenuation of the high-frequency anthropogenic signal, which was correlated with activity limitations in those regions.
The most pronounced effects occurred in densely populated areas, such as cities, but, according to the researchers, the effect is noticeable even in low-density rural areas. And even seismological stations installed far away from people have seen changes, for example, a station installed in Germany at a depth of 150 meters below the Black Forest.
This suggests that the anthropogenic seismic wave field is much broader than previously thought, which is very useful since the Black Forest seismic station has often been used as a “low noise” reference point.
This period of silence, the decline in human activity on the planet caused by the global pandemic, which some scientists have already called anthropopause, is also called a gift of science by seismologists. And it gives two reasons for such an evaluation.
First, by comparing the pre-pandemic period with the quarantine period, scientists can better characterize human-induced seismic noise than ever before.
Second, when the roar decreases, scientists can hear earthquake signals much more clearly than would normally have been drowned out by the noise of the human roar, especially if those signals only reach seismometers located near densely populated cities.
“As urbanization expands and the world population grows, more and more people will live in geologically dangerous areas. Therefore, in the future, it will be more important than ever to separate natural seismic phenomena from man-made grunts for that we can better listen and observe the movements of the Earth under our feet. And this research may be the starting point for this new field of research, “explained Thomas Lecocq, seismologist and lead author of the Royal Observatory of Belgium.
In some regions of the world, seismic activity levels are already beginning to return to pre-pandemic levels (although pandemic activity is far from normalizing globally), but these inactive months have already provided a new level of Invaluable base noise from which future seismic data will be evaluated.
VIDEO: The effect of COVID-19 global blockade is anthropogenic seismic noise
The human population continues to grow. This in turn will increase the complexity of seismic observations (the more people, the more traffic), so the ability to clearly distinguish some of the anthropogenic noise from the general seismic signal will greatly facilitate the task of detecting actual Earth movements. , especially those who endanger property or lives.
“The coronavirus-induced operational constraints have given us an insight into how humans and natural noise interact within Earth. We hope this knowledge will serve as the basis for new research that will help us better listen to Earth and understand the natural signals we would normally lose, “said Hicks.
The results of the study were published in the journal Science.
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