The eerie silence of lock downed cities spread across the globe as people fled the new coronavirus.
Seismologists who measure the shaking of Earth’s surface the drop in this kind of human caused noise was unprecedented.
Researchers examined data from a global network of 268 seismic stations in 117 countries.
They tracked seismic sound from late January as the lockdown in China spread to Europe and the rest of the world along with the virus.
European scientists say 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.
The study is by Imperial College London and the Royal Observatory of Belgium.
Seismologist and co-author Dr Stephen Hicks says: “It should allow us to really understand what contributes to the anthropogenic (created by human activity) seismic noise and then to find out how can we model it how can we how can we sort of predict that five different regions, then we might be able to remove that from our real time seismic signals and to actually detect some smaller earthquakes, for example, that we might not have anticipated to occur during normal times, so that quiet periods might reveal some hidden signals. And that’s really important, for example, for for earthquake hazard to understand how stress is being built up or released along geological faults, inactive tectonic plate boundaries.”
These months of silence might make us forget the impact of humankind in the cities, the festivities, the crowds, the traffic.
“The image we give is that if you’re on a stage in front of a stadium full of crowd waiting for your concert. If everyone is quiet and someone at the back says, hey, you hear it. If everyone talks, you don’t. And so this is hello from the Earth. We hear it, we hear the smallest hellos during this quiet period. So for places in cities where you have fault zones close by, and there’s numerous places in the world that are like that, close to fault zones, or on zones, then this quietening is important,” says lead author Dr Thomas Lecocq.
The scientists are working with a range of researchers to see whether this dramatic change in environment had a significant impact on the atmosphere and surrounding wildlife.
“The teams, they used satellites to show that the S02 (sulphur dioxide) and N02 (nitrogen dioxide) components so the chemical change of the atmosphere, composition sorry of the atmosphere has changed quite, quite strongly in the last last three months. Not necessarily everywhere, and the way we thought about it. So, for example, they still see dust in the air, and that didn’t really diminish because probably dust is not linked to the to the traffic as far as understand that is their speciality. But so we linking also with them to see, okay, what if we bring an observable that is independent, it’s a physical observation, probably narrow observation around the station, maybe a few kilometres around each station. But if they can extract a grid point from their satellite observation, maybe we can compare also, air pollution and seismic waves,” says Lecocq.
The scientists are now after further evidence, but Lecocq says if we were able to make a dramatic change for our survival against the virus, we should be able to do the same for other important human goals.
“These cities are super quiet, I mean, were at least during this period, it was for a bad reason but it’s also linked to a fact that we all as individuals have decided that we would make small efforts altogether, and altogether, we made it to prevent this virus to spread. But what if we’re just altogether do something else for something also as big as climate change, for example. So this, this, this witnessing this this change, we saw all over the world, this wave of changes in seismic noise, but also into quietening that you can hear with your ears. This is just fantastic in terms of like the science and the link with what we feel and what we need to do as humans to to make this planet and the environment better.”
The study is being published in the journal Science today (23 July 2020).