COVID-19 lockdown caused 50 percent global reduction in human-linked
Earth vibrations

Date:
July 23, 2020
Source:
Imperial College London
Summary:
The lack of human activity during lockdown caused human-linked
vibrations in the Earth to drop by an average of 50 percent between
March and May 2020.



FULL STORY ========================================================================== [Seismograph (stock | Credit: (c) Anna / stock.adobe.com] Seismograph
(stock image).

Credit: (c) Anna / stock.adobe.com [Seismograph (stock | Credit: (c)
Anna / stock.adobe.com] Seismograph (stock image).

Credit: (c) Anna / stock.adobe.com Close The lack of human activity
during lockdown caused human-linked vibrations in the Earth to drop by
an average of 50% between March and May 2020.


==========================================================================
This quiet period, likely caused by the total global effect of social distancing measures, closure of services and industry, and drops in
tourism and travel, is the longest and most pronounced quiet period of
seismic noise in recorded history.

The new research, led by the Royal Observatory of Belgium and five
other institutions around the world including Imperial College London,
showed that the dampening of 'seismic noise' caused by humans was more pronounced in more densely populated areas.

The relative quietness allowed researchers to listen in to previously
concealed earthquake signals, and could help us differentiate between
human and natural seismic noise more clearly than ever before.

Co-author Dr Stephen Hicks, from Imperial's Department of Earth Science
and Engineering, said: "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." The paper is published today
in Science.



========================================================================== Anthropause Measured by instruments called seismometers, seismic noise
is caused by vibrations within the Earth, which travel like waves. The
waves can be triggered by earthquakes, volcanoes, and bombs -- but also
by daily human activity like travel and industry.

Although 2020 has not seen a reduction in earthquakes, the drop in
human-caused seismic noise is unprecedented. The strongest drops were
found in urban areas, but the study also found signatures of the lockdown
on sensors buried hundreds of metres underground and in more remote areas.

Human-generated noise usually dampens during quiet periods like over the Christmas/New Year period and Chinese New Year, and during weekends and overnight. However, the drop in vibrations caused by COVID-19 lockdown
measures eclipse even those seen during these periods.

Some researchers are dubbing this drop in anthropogenic (human-caused)
noise and pollution the 'anthropause'.



==========================================================================
Dr Hicks said: "This is the first global study of the impact of the
coronavirus anthropause on the solid Earth beneath our feet." To gather
the data, researchers looked at seismic data from a global network of 268 seismic stations in 117 countries and found significant noise reductions compared to before any lockdown at 185 of those stations. Beginning
in China in late January 2020, and followed by Europe and the rest of
the world in March to April 2020, researchers tracked the 'wave' of
quietening between March and May as worldwide lockdown measures took hold.

The largest drops in vibrations were seen in the most densely
populated areas, like Singapore and New York City, but drops were
also seen in remote areas like Germany's Black Forest and Rundu in
Namibia. Citizen-owned seismometers, which tend to measure more localised noise, noted large drops around universities and schools around Cornwall,
UK and Boston, USA -- a drop in noise 20 per cent larger than seen during school holidays. Countries like Barbados, where lockdown coincided with
the tourist season, saw a 50 per cent decrease in noise. This coincided
with flight data that suggested tourists returned home in the weeks
before official lockdown.

Listening in Over the past few decades, seismic noise has gradually
increased as economies and populations have grown.

The drastic changes to daily life caused by the pandemic have provided
a unique opportunity to study their environmental impacts, such as
reductions in emissions and pollution in the atmosphere. The changes
have also given us the opportunity to listen in to the Earth's natural vibrations without the distortions of human input.

The study reports the first evidence that previously concealed earthquake signals, especially during daytime, appeared much clearer on seismometers
in urban areas during lockdown.

The researchers say the lockdown quietening could also help them
differentiate between human-caused noise and natural signals that might
warn of upcoming natural disasters.

Lead author Dr Thomas Lecocq from the Royal Observatory of Belgium said:
"With increasing urbanisation 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." The study's authors hope that their work will spawn further research on the seismic lockdown, as well as finding previously hidden
signals from earthquakes and volcanoes.

Dr Hicks said: "The lockdowns caused by the coronavirus pandemic may have
given us a glimmer of insight into how human and natural noise interact
within the Earth. We hope this insight will spawn new studies that help
us listen better to the Earth and understand natural signals we would
otherwise have missed."

========================================================================== Story Source: Materials provided by Imperial_College_London. Original
written by Caroline Brogan. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Thomas Lecocq, Stephen P. Hicks, Koen Van Noten, Kasper van Wijk,
Paula
Koelemeijer, Raphael S. M. De Plaen, Fre'de'rick Massin, Gregor
Hillers, Robert E. Anthony, Maria-Theresia Apoloner, Mario
Arroyo-Solo'rzano, Jelle D. Assink, Pinar Bu"yu"kakpınar,
Andrea Cannata, Flavio Cannavo, Sebastian Carrasco, Corentin
Caudron, Esteban J. Chaves, David G. Cornwell, David Craig,
Olivier F. C. den Ouden, Jordi Diaz, Stefanie Donner, Christos
P. Evangelidis, La"slo Evers, Benoit Fauville, Gonzalo A. Fernandez,
Dimitrios Giannopoulos, Steven J. Gibbons, Ta'rsilo Girona, Bogdan
Grecu, Marc Grunberg, Gyo"rgy Hete'nyi, Anna Horleston, Adolfo Inza,
Jessica C. E. Irving, Mohammadreza Jamalreyhani, Alan Kafka, Mathijs
R. Koymans, Celeste R. Labedz, Eric Larose, Nathaniel J. Lindsey,
Mika McKinnon, Tobias Megies, Meghan S. Miller, William Minarik,
Louis Moresi, Vi'ctor H. Ma'rquez-Rami'rez, Martin Mo"llhoff,
Ian M. Nesbitt, Shankho Niyogi, Javier Ojeda, Adrien Oth, Simon
Proud, Jay Pulli, Lise Retailleau, Annukka E. Rintama"ki, Claudio
Satriano, Martha K. Savage, Shahar Shani-Kadmiel, Reinoud Sleeman,
Efthimios Sokos, Klaus Stammler, Alexander E. Stott, Shiba Subedi,
Mathilde B. So/rensen, Taka'aki Taira, Mar Tapia, Fatih Turhan, Ben
van der Pluijm, Mark Vanstone, Jerome Vergne, Tommi A. T. Vuorinen,
Tristram Warren, Joachim Wassermann, Han Xiao. Global quieting
of high-frequency seismic noise due to COVID-19 pandemic lockdown
measures. Science, July 23, 2020; DOI: 10.1126/ science.abd2438 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200723143728.htm

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