Earth shaking less as coronavirus lockdowns curb human-related seismic activity

Normally there’s a whole lot o’ shakin’ going on. But during lockdown, not so much.

Without humans and their mechanical devices stomping and rumbling across the planet, Earth’s surface has calmed down — and it’s showing up on seismology instruments everywhere.

It’s a bonanza for researchers, giving them “a rare opportunity to study the modern world under some truly bizarre conditions,” The Atlantic reported, “and they’re scrambling to collect as much data as they can.” 

It started with an observation in Brussels, where seismologist Thomas Lecocq, with the Royal Observatory of Belgium, noticed that vibrations due to human activity dropped by about a third after lockdown measures were imposed in an effort to curb the spread of coronavirus. 

The university’s seismometer registered the drop after schools, restaurants and other public venues closed down, and nonessential travel halted, in the middle of last month, Lecocq told Nature. 

The drop may be as steep as a 50% reduction,  a decrease normally seen only briefly around major holidays.

The drop is making the instruments more sensitive too, he said. 

“This is really getting quiet now in Belgium,” he told Nature. 

It’s the noise decrease (not) heard round the world, as seismologists in France, New Zealand and the U.S. have seen similar drops.  

Here’s daily mode noise power from a station in Los Angeles over the past month,” tweeted California Institute of Technology PhD student Celeste Labedz, along with a graph. “The drop is seriously wild.” 

In London, seismologist Paula Koelemeijer doesn’t have to go farther than her living room. A tissue-box-sized seismometer at the foot of her fireplace has registered the change in nearby train noise, she told The Atlantic. Now it’s free to pick up more subtle, natural vibrations, such as distant earthquakes, she said. 

“It’s very literally reflecting a slowdown of our lives,” Koelemeijer told The Atlantic. “Normally we wouldn’t pick up a 5.5 [magnitude earthquake] from the other side of the world, because it would be too noisy, but with less noise, our instrument is now able to pick up 5.5’s with much nicer signals during the day.”  

Also dropping, besides the seismic noise, is audible noise — both above and below the ocean. The underwater cacophony imposed by thousands of cruise ships other vessels has abated with the suspension of most cruise lines. Given the already documented effect of that noise on marine life, researchers are also eager to study the quieter ocean — while it lasts. 

“Just pulling those cruise ships out of the water is going to reduce the amount of global ocean noise almost instantaneously,” Michelle Fournet, a marine ecologist at Cornell who studies acoustic environments, told The Atlantic. “We’re experiencing an unprecedented pause in ocean noise that probably hasn’t been experienced in decades.”