Earth’s crust shaking less as people stay home

The COVID-19 lockdowns globally have not only made air breathable or rivers clean but have also resulted in the way our Earth moves, as researchers now report a drop in seismic noise (the hum of vibrations in the planets crust) because transport networks, real estate and other human activities have been shut down.

According an article inthe journal Nature, efforts to curb the spread of coronavirus mean that theplanet itself is moving a little less, which could “allow detectors tospot smaller earthquakes and boost efforts to monitor volcanic activity andother seismic events”.

   

Vibrations caused by moving vehicles and industrialmachinery produce background noise, which reduces seismologists’ ability todetect other signals occurring at the same frequency.

“A noise reduction of this magnitude is usually onlyexperienced briefly around Christmas,” said Thomas Lecocq, a seismologistwith the Royal Observatory of Belgium in Brussels which has observed the dropin seismic noise.

Data from a seismometer at the observatory show thatmeasures to curb the spread of COVID-19 in Brussels caused human-inducedseismic noise to fall by about one-third.

In Belgium, scientists report at least a 30 per centreduction in that amount of ambient human noise since lockdown began there.

The current drop has boosted the sensitivity of theobservatory’s equipment, improving its ability to detect waves in the same highfrequency range as the noise, said the Nature article.

However, not all seismic monitoring stations will see aneffect as pronounced as the one observed in Brussels.

According to Emily Wolin, a geologist at the US GeologicalSurvey in Albuquerque, New Mexico, many stations are purposefully located inremote areas to avoid human noise.

“These should see asmaller decrease, or no change at all, in the level of high-frequency noisethey record,” she was quoted as saying.

The fall in noise could also benefit seismologists who usenaturally occurring background vibrations, such as those from crashing oceanwaves, to probe Earth’s crust.

A fall in human-induced noise could boost the sensitivity ofdetectors to natural waves at similar frequencies

“There’s a big chance indeed it could lead to bettermeasurements,” said Lecocq.

The reduction in seismic activity, like reduction in airpollution, also show that people are adhering to social distancing guidelines.

“From the seismological point of view, we can motivate people to say, ‘OK look, people. You feel like you’re alone at home, but we can tell you that everyone is home. Everyone is doing the same. Everyone is respecting the rules,’” Lecocq told CNN.

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