Seismic background noise has been reduced due to the worldwide COVID-19 lockdowns a new study shows. There are thousands of seismic stations around the world. Those stations record the movement of plates using seismometers. As humans go about their daily life they shake the ground ever so slightly. We shake the ground when we drive, cheer at a sporting event, and construct buildings. Even though small compared to our entire planet, those small movements are picked up on the same seismometers that monitor Earth’s plate movements.
Since human movements are fairly predictable they can be identified and canceled out as background noise when looking at seismograms. A reduction of this noise was first observed in China in January 2020. Then, from March to May North America and Europe saw reductions in seismic noise by almost 50%. These reductions are significant because they mask high-frequency movements that get canceled out with the human noise. During the period from March to May, geophysicists were able to observe more discrete seismic activity.
“The noise level we observe during lockdowns lasted longer and was often quieter than the Christmas to New Year period.”
Typically, geophysicists see a reduction in anthropogenic background noise around holidays and on weekends. The reductions in noise were significantly greater than any reduction in the past. The drastic reduction in background noise has put a renewed focus on what this noise can be used for and what else it could be hiding.