Reduction in human-induced seismic noise during the pandemic lockdown

Change between December 2019 and May 2020 of the amplitude of vibrations (ground
Change between December 2019 and May 2020 of the amplitude of vibrations (ground movement caused by human activity) detected by seismic sensors in different cities. Each line shows the variations in amplitude in each city. Each pixel represents one day. White dots correspond to the start of lockdown in each given city. In blue are low vibration amplitudes, observed more frequently after lockdown began, but also during this year’s New Year celebrations and on the weekends. © Thomas Lecocq et al.

A team of 76 seismologists, including several French scientists from the CNRS, the Paris Institute of Earth Physics (IPGP), Université de Paris, Université de Strasbourg and the French National Research Institute for Sustainable Development (IRD) 1 discovered that the lockdown measures used in the fight against the spread of COVID-19 have led to a 50% reduction in seismic noise due to human activity across the globe between January-June 2020. The seismologists were taken aback by the extent of the reduction and the hitherto unexpected impact human activity has on the subsurface. By analysing data from more than 300 seismic stations worldwide, the scientists were able to observe the decrease, even identifying the "wave" of lockdowns moving through China, then through Italy to finally reach the rest of the world. This seismic quiet is due to the physical distancing measures set up by public authorities, the reduction in economic and industrial activity as well as in tourism and travel. In addition to this unexpected discovery, the findings published on 24 July 2020 in an article in Science, help to better quantify seismic noise caused by human activity. The researchers suggest using seismic noise to monitor this activity as an alternative to the use of personal data. These measures may also lead to a better understanding of certain natural phenomena normally drowned out by the seismic noise.