* Study Finds Blocks Reduce Human-Linked Seismic Noise
* It allowed scientists to listen to Earth’s natural vibrations.
* The seismic silence time is more pronounced than ever recorded
By Kate Kelland
LONDON, July 23 (Reuters) – COVID-19 blocks worldwide led to the longest and most pronounced reduction in human-related seismic vibrations ever recorded, sharpening scientists’ ability to hear Earth’s natural signals and detect earthquakes, according to a study found Thursday.
The vibrations travel through the earth like waves, creating seismic noise from earthquakes, volcanoes, wind, and rivers, as well as human actions such as travel and industry.
In the study, published in the journal Science and conducted using international seismometric networks, the scientists found that human-linked earth vibrations decreased by an average of 50% between March and May this year.
“The 2020 Silent Seismic Noise Period is the longest and most prominent global anthropogenic seismic noise reduction on record,” they wrote. The work was co-directed by the Royal Belgian Observatory and five other institutions using data from 268 monitoring stations in 117 countries.
Starting in China in late January, and followed by Europe and the rest of the world in March through April, researchers saw “a wave of calm” as global blocking measures were taken to curb the coronavirus pandemic.
Travel and tourism were practically interrupted, millions of schools and industries closed, and many people were confined to their homes.
The relative quiet allowed scientists to “listen” in more detail to the earth’s natural vibrations, said Stephen Hicks, a seismologist at Imperial College London, who co-directed the work.
“It has produced a new window on natural seismic signals and could allow us to see more clearly than ever what differentiates human and natural noise,” he said.
The study said its findings also showed that seismologists can help establish how long it takes for people to react to the imposition and lifting of blocking measures.
The largest falls in human-induced vibrations were observed in densely populated areas such as Singapore and New York, but falls were also observed in remote areas such as Germany’s Black Forest and Rundu in Namibia. Barbados, where the blockade coincided with the tourist season, experienced a 50% drop in seismic noise. (Report by Kate Kelland, Philippa Fletcher edition)
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