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Thursday, January 28, 2021
Ian Cubitts
Ian Cubitts

Human noise down 50% globally during lockdown, study shows

COVID-19 lockdown restrictions have caused a 50% reduction in seismic noise globally.

The global study, which included researchers from the Australian National University (ANU), saw the biggest reduction in human generated noise from over 300 seismic stations around the world.

ANU researcher, Associate Professor Meghan Miller, said while most Australian data showed similar trends, Canberra’s seismic noise didn’t reduce as much as other cities.

“The Canberra seismic station data showed slightly lower noise levels than normal, but higher than other cities such as Melbourne,” she said. 

“It would be because a lot of government offices and public agencies were still open during the lockdown and there was still a lot of commuting and moving around.”

Seismometers are used within stations to record vibrations, knows as seismic waves, measuring them after earthquakes.

There are 50 seismic stations around Australia, with one stationed in Canberra at Melrose High School in Pearce.

Professor Miller said while many cities are seeing seismic noise increase to normal levels following COVID-19 lockdown, data in Melbourne is currently showing a second reduction.

“It is interesting to see the data right now in Victoria going back to low levels as they move into a second lockdown period,” she said.

“All of the stations are low over Christmas when people are usually on holidays and as soon as lockdown started you can see there is a dramatic decrease.

“Once school started back, they were ramping back up to almost a normal level, but it has decreased dramatically in Melbourne.”

The reduction in noise has shown researchers previously concealed earthquake signals, which are not always visible when human generated noise is at a higher level.

Professor Miller said one interesting part of the data was the visible reduction in noise while community sport was off limits.

“If you looked at data from schools, the noise levels went up when students returned but at that point sports weren’t allowed to start,” she said.

“At the time, even when school went back, with no school sports on a Saturday morning you could see a dramatic decrease to the regular level of noise.”

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