As international governments began to implement measures of social isolation due to the COVID-19 pandemic, the world has become more silent. Now, a new study reveals that the confinement recorded between March and May was the longest period of silence ever recorded in human history.
According to the recently published study in the scientific journal Science, the confinement period emerged as a unique opportunity for researchers in the field of seismology to realize the impact of human activities on Earth's vibrations, known as seismic noise.
Scientists indicate that humans are the third largest source of seismic noise. The vibrations caused by human activities end up mixing with the natural sounds of the Earth, making it difficult in many cases for the work of seismologists.
The researchers collected data from 268 seismic monitoring stations around the world, combining it with information from the Apple and Google mobility reports.
In all, 185 of the seismic monitoring stations demonstrated significant reductions in seismic noise. The study details that the silence began in late January in China and, by mid-March, had already spread to the rest of the world.
Although the period between Christmas and Chinese New Year is generally the quietest, the differences from previous years are striking. For example, in Sri Lanka, there was a reduction in the order of 50%, the highest figure identified. Even seismic sensors that are at a great depth were able to detect the reduction in human activities.
It is recalled that, in March, several images captured by drones all over the world already revealed a panorama of deserted cities in the United States due to the confinement.
The images revealed empty parks and stadiums and the gigantic avenues, usually with big traffic jams, without cars. All the general activity seemed to be non-existent in the different cities, as you can see on the video of different locations that we compiled.
In the same month, the aerial photographs published by the space technology company Maxar showed the before and after of spaces that are normally quite busy, now with far fewer people. The visas included tourist attractions, from religious destinations to theme parks, but also airports, which were emptied as business and leisure trips were canceled.
What do ground observation data tell us about the impact of COVID-19?
In addition to the measuring instruments present on Earth, satellites have helped scientists to understand the impact of COVID-19 on terrestrial activities. The pandemic brought the tourism sector to a virtual standstill, and in June, images captured by ESA's Copernicus Sentinel-2 mission showed anchored vessels and numerous planes parked on the runways.