Staying at home has led to a notable reduction in the hum of ground vibrations in the UK generated by human activities such as air and road traffic and industrial work, geoscientists have said.
Experts said that compared to noise levels before lockdown, signals from seismometers across the country show ambient noise caused by people going about their daily lives has dropped between 20% and 50% in the last five weeks.
Seismometers are normally used to record earthquakes and volcanic activity, but they also track the vibrations in the planet’s upper crust, or seismic noise, caused by humans.
Dr Brian Baptie, head of seismology at the British Geological Survey in Nottingham, told the PA news agency: “We have got a network of around 100 sensors all across the UK measuring seismic activity.
“What we have since lockdown is that noise levels at nearly all of our stations have gone down by somewhere between 20% to 50%.”
The experts said the reduction in seismic noise has been higher in areas where there is a lot of human activity, such as airports, train stations, busy roads, construction sites and even schools and universities.
Dr Paula Koelemeijer, a global seismologist at Royal Holloway, University of London, said a seismometer located near London King’s Cross station in London recorded a 30% drop in seismic noise while a device at her home in Twickenham in west London has shown a noise reduction of 25%, compared to the pre-lockdown noise levels.
She told PA: “This suggests more people are in their houses, there is less car traffic, and fewer trains are running.”
Meanwhile Dr David Cornwell, a geophysicist at the University of Aberdeen, said compared with peak noise during a normal day, the noise levels at his university campus have dropped by 65% since students were sent home five weeks ago.
This meant some of his seismometers are able to pick up natural noises, like those generated by the wind and the sea, he added.
These effects have also been observed around the world, with more than two billion people currently staying at home.
Dr Cornwell told PA: “Globally, other seismologists have reported noise levels in cities to be between 20% and 50% lower compared to the noise levels recorded before lockdown, but there have been a few cases, such as one in Nepal, where the reduction has been as large as 80%.”
The drop in human-generated noise has also given scientists an opportunity to spot smaller earthquakes and other seismic events from around the world.
Dr Cornwell told PA: “If a minor earthquake happened in Japan, I would be able to record it in my office or in our instruments across the UK.”
Meanwhile, Reuben Peckham, director of 24 Acoustics, a consultancy firm which helps architects design noise-sensitive buildings, said his sound-measuring instruments at a construction site in Surrey have been picking up unusual noises during the day, like the sounds of birds, that would normally be masked by the noises from heavy traffic or construction machinery.
He told PA: “Birdsong has definitely been more prevalent in our monitors since lockdown.”