seismograph earthquakes

European lockdown a boon to seismologists checking Earth’s vibrations

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Seismologists across Europe have been looking at the effects of the coronavirus lockdown on seismic activity and found a notable drop in ground vibrations.

A seismologist at the Royal Observatory in Belgium discovered that seismic levels had fallen between 30 and 50 per cent since the middle of last month, which coincides with the country closing schools and businesses as part of the lockdown.

Scientists say the reduction in seismic noise may help them to see signals from earthquakes more clearly that are normally buried in the noise.

In theory, this reduction in noise should help them to detect more earthquakes in the UK, Europe and around the world, according to Brian Baptie, a seismologist at the British Geological Survey (BGS) in Edinburgh.

“We measure ground vibrations from earthquakes using seismometers,” he said. “These are incredibly sensitive, so they also pick up other sources of vibration, too, including human activity such as road traffic, machinery and even people walking past. All these things generate vibrations that propagate as seismic waves through the Earth.

“We compared the average daytime noise levels at seismic stations in the UK in the two-week period since the start of the Covid-19 lockdown with the average noise levels for the beginning of the year. The results show reductions in noise levels at most of our stations of between 10-50 per cent.”

He said it was “important” to note that there hadn’t been any change in seismic activity, merely the ability of scientists to detect it. He also expects activity to increase back to former levels once lockdown protocols are ended.

There are around 100 seismic monitors located across the UK, with reductions in noise most prevalent in areas with lots of human activity, such as airports, train stations, busy roads, construction sites and even schools and universities.

City-based detectors - those closest to urban centres - are most likely to see the biggest improvements recording locations of earthquakes and aftershocks.

“We would expect those sensors that are closest to sources of human-generated noise to show the biggest improvement, while those that are already in quiet rural areas may not change so much,” said Baptie. “That means that city-based detectors will get better.”

For now, the team are excited by the prospect of being able to get more specific data from the recordings, thanks to the greater sensitivity.

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