Seismologists say a quieter Earth on pandemic lockdown means their instruments are picking up far more information.
Documenting seismic activity is vital to several different kinds of science.
There are similar notable changes to measurements in infrasound and weather.
Scientists say the “quieter” Earth during protective self-quarantine has reduced the ambient seismic noise. Human activity of all kinds, as we travel and gather and drive around, generates vibrations that distort measurements from finely tuned seismic instruments. In Belgium, scientists report a 30 percent reduction in that amount of ambient human noise since the COVID-19 (coronavirus) lockdown began there.
Now, the resulting quiet means surface seismic readings are as clear as the ones scientists usually get from the same instruments buried 100 meters beneath the Earth’s surface, making measurements more more specific and easier to use and understand. Any seismic noise that falls into the same instrument range as human noise is suddenly much clearer, like if you were trying to listen to two people talking and one simply stopped.
No cost of human life is worth any exchange of scientific data, of course, and the sooner our global self quarantine can safely end, the better. But if the self quarantine extends longer, scientists say they’ll continue to notice new ways their instruments and readings are changing.
We can never seamlessly compare conditions over long time periods because of how many factors are at play, but a much quieter Earth might give measurements similar to ones a hypothetical 19th century scientist could observe. And having this data as a comparison point could prove useful going forward.
There are practical, everyday ways that seismic activity measurements are used. The Global Seismographic Network (GSN) is a set of hundreds of monitoring labs around the world where earthquakes and other seismic activities are recorded and addressed. This includes triangulating locations for aftershocks. Scientists can’t predict earthquakes—they can only measure and spread information as quickly as possible.
Human activity can also directly induce earthquakes, which scientists say is one reason the number of earthquakes in the American midwest, for example, has increased since the beginning of the fracking boom. They say it’s not fracking itself, but the associated waste fluid disposal that can trigger these earthquakes. Even so, these aren’t predictable—just identifiable in hindsight and in areas of known higher risk.
Seismology isn’t the only field experiencing a temporary sea change due to COVID-19 (coronavirus) human activity. Weather expert Dr. Marshall Shepherd reported that infrasound, which is noise below the frequency of human hearing but in this case not seismic noise, has also decreased. Shepherd's colleague told him that one of the big local examples of infrasound was from a wind tunnel research facility, and when that facility temporarily closed, a large amount of infrasound went quiet.
Climate and weather science are experiencing fluke readings, too. Much has been made of how China’s amount of pollution has fallen during lockdown, similar to the impact during a no-fly time in 2010, when a volcano in Iceland blanketed Europe with ash. (That event was balanced out perhaps, by how much toxic gas came out of the volcano.) And weather observation and prediction might suffer because of the almost total stoppage of passenger flights, which record important data all day every day.
No one asked for this time of global self quarantine, but scientists are helping us document what’s happening from the ground up—and underground.
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