Earth's vibrations quieted during COVID-19 lockdowns

July 24 (UPI) -- Planet Earth didn't jiggle as much as usual between March and May of this year, according to researchers.

A new study, published in the journal Science, suggests the COVID-19 pandemic -- and the resulting restrictions on businesses and the movements of citizens -- led to a reduction in seismic noise.

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.

When researchers measured the reduction in human-caused seismic noise, they found the most significant declines were recorded near urban centers, particularly New York and Singapore. But even seismic sensors buried deep underground registered drops in human-caused seismic noise.

Researchers analyzed noise declines across 268 seismic stations in 117 countries. The pandemic's dampening effect first appeared in China, followed by Europe and North America.

The reduction in vibrations is the latest characteristic of what some scientists are calling the "anthropause" -- the decline in pollution and noise resulting from the global pandemic.

"This is the first global study of the impact of the coronavirus anthropause on the solid Earth beneath our feet," study co-author Stephen Hicks, a seismologist at Imperial College London, said in a news release.

The study also analyzed seismic data recorded by citizen-operated seismometers, which pick up more localized seismic activity. These sensors revealed especially stark declines in seismic noise on college campuses.

Over the last few decades, as global cities and human populations have increased in size, human-caused seismic noise levels have slowly increased. Seismic noise produced by humans can make it harder for sensors to pick up on natural seismic activity.

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 earthquake, landslide or volcanic eruption.

"With increasing urbanization and growing global populations, more people will be living in geologically hazardous areas," said lead study author Thomas Lecocq, a scientist at the Royal Observatory of Belgium.

"It will therefore become more important than ever to differentiate between natural and human-caused noise so that we can 'listen in' and better monitor the ground movements beneath our feet," Lecocq said. "This study could help to kick-start this new field of study."