When the World Stood Still: Seismic Noise Reduced by Coronavirus-Induced Lockdowns, New Study Claims

Seismic noise is caused by vibrations within the earth that can be triggered by natural processes like earthquakes and volcanic eruptions, but can also be caused by human activity, such as during construction work, transport, or simply by thousands of people cheering at a stadium during a rock concert.
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Terms like "self-isolation" and "nationwide lockdown" might trigger a strong sense of nausea for people in most countries, but it turns out that the months-long house arrest that many of us went through, although very challenging, has had a positive effect. A new study led by the Royal Observatory in Belgium claims that there has been a 50 percent reduction in global seismic noise in the past months, which scientists attribute to the changes in life brought about by the coronavirus pandemic.

In the study, which was published on 23 July in the journal Science, the researchers analysed data from 268 seismic stations in 117 countries and found that the world had experienced a wave of quietening that started in January in China and was followed by Europe and the rest of the world in March, April, and May.

"This quiet period is likely the longest and largest dampening of human-caused seismic noise since we started monitoring the Earth in detail using vast monitoring networks of seismometers. Our study uniquely highlights just how much human activities impact the solid Earth, and could let us see more clearly than ever what differentiates human and natural noise”, said one of the study's co-authors, Dr Stephen Hicks from the Department of Earth Science and Engineering at Imperial College London.

Scientists say that thanks to the dramatic drop in seismic noise produced by human activity they were able to listen to previously undetected earthquakes signals. This means that in the future, the study will help them differentiate between noise caused by humans and noise caused by natural events, which will in turn help geologists warn about upcoming natural disasters. Dr Thomas Lecocq, the lead author of the research, said its findings might kick-start a new field of study.

"With increasing urbanization and growing global populations, more people will be living in geologically hazardous areas. 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. This study could help to kick-start this new field of study", said Dr Lecocq.
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