Half the world is on lockdown. So, the constant hum of cars, trucks, trains and heavy machinery has stopped, drastically reducing the intensity of the vibrations rippling through the Earth's crust. Seismologists, who use highly sensitive equipment, have noticed a difference in the hum caused by human activity, according to Fast Company.

In Belgium, scientists report at least a 30 percent reduction in that amount of ambient human noise since lockdown began there, according to Popular Mechanics. Scientists say this may be beneficial to seismologists, as it will allow them to detect minor earthquakes and to improve their tracking of volcanic activity and other seismic events, as Nature reported.

Thomas Lecocq, a geologist and seismologist at the Royal Observatory in Belgium, first pointed out the phenomenon, according to CNN. He noticed the 30 to 50 percent reduction since the country started its social distancing measures in mid-March and businesses and industries shut down. Lecocq said the vibrations he has seen are on par with what it is like on Christmas Day in Belgium.

While most seismologist instruments are placed outside cities to avoid vibrations caused by urban centers, the one in Brussels was built more than 100 years ago and the city has expanded around it since then. That proximity to the city accounts for the dramatic dip in seismic activity, as CNN reported.

The seismic effect of one car, one train, or one jackhammer is miniscule, together they crescendo in a significant din background noise that reduces seismologists ability to detect other signals at the same frequency, according to Nature.

The dips from human activity have been noticed in other cities around the world, including in London and Los Angeles, as Fortune reported. In a tweet, a British seismologist, shared data from a sensor near a motorway, showing large dips in daytime activity.