Coronavirus may have inadvertently caused Earth to vibrate less, with lockdown measures leading to a huge drop in the use of industrial machinery and transportation around the world.
Seismologists have said that since measures to curb the spread of the virus were put in place, there has been a noticeable drop in the planet’s “seismic noise.” This is the persistent vibration of the ground as a result of a multitude of factors, including human activity.
These vibrations are recorded by seismometers—instruments that measure ground motion that are normally used to monitor events like earthquakes and volcanic eruptions. The background seismic noise has to be taken into account when scientists are studying geological events.
The COVID-19 pandemic began in December last year, when cases of the virus were identified in the city of Wuhan, China. The number of cases rose quickly, and by the end of January, the World Health Organization had confirmed 9,826 cases across 20 countries.
Since then, this figure has increased almost 100 fold. At the time of writing, the Johns Hopkins University dashboard tracker had confirmed over 877,000 cases in 180 countries.
To curb the spread of the virus, containment measures have been put in place in countries across the globe, aimed at limiting the movement and contact of people. At one point, a third of the global population was under some form of lockdown. These measures brought a halt to many industries and transport networks.
It is thought the drop in vehicles on the roads and industrial output is so extensive, there could be a huge fall in carbon dioxide emissions, with carbon monoxide emissions falling by almost 50 percent compared to 2019, the BBC reports.
But the huge fall in the use of industrial machinery and vehicles also appears to have led to a reduction in seismic noise. Thomas Lecocq, a seismologist at the Royal Observatory of Belgium in Brussels, said a huge drop had been observed, Nature magazine reports. His recordings suggest manmade seismic noise had fallen by around one third. “This is really getting quiet now in Belgium,” he is quoted as saying.
A similar drop was reported by Stephen Hicks, at the U.K.’s Imperial College London. On Twitter, he presented graphs showing the fall in average daytime background seismic noise. “It seems quite clear that over the last few days, the increase in noise level at dawn… is much less steep than over the past few weeks,” he Tweeted. “I guess this is due to a much weaker morning rush hour—fewer people commuting and no school runs.”
Celeste Labedz, a geophysics PhD student at Caltech, responded saying she had observed a similar reduction in Los Angeles. “The drop is seriously wild,” she said.
Ian Main, Professor of Seismology and Rock Physics at the U.K.’s University of Edinburgh, told Newsweek it would be surprising if there had been no drop in ‘cultural noise’ from transport and industry as a result of the lockdown. This would be more apparent at stations near these sources, he said.
“For lower frequencies associated with geophysical sources e.g. ocean storms… I would not expect to see any significant change,” he said, adding it may be that “Earth is vibrating in between earthquakes less than normal, but only at higher frequencies generated by cultural noise.”
The drop in seismic noise could help seismologists studying earthquakes and volcanoes to better monitor activity. Without the background noise, spotting small changes in seismic activity may be easier. “There’s a big chance indeed it could lead to better measurements,” Lecocq told Nature.
This article has been updated to include comments from Ian Main.