Seismometers around the world mainly act as ears to the ground to learn about the Earth’s subsurface structure and dynamics. Still, seismic waveforms record more than earthquakes and volcanic activity. Wind and ocean waves generate seismic noise, while seismographs in the vicinity of cities record the occasional rock concert, rugby and football game.
In the battle against the COVID-19 pandemic, seismic stations have recorded a reduction in anthropogenic noise sources. In New Zealand that has been reported by Geonet and the Ru educational seismic network, for example. In general, nights are quieter than days, and weekends are quieter than weekdays. However, after the closing of schools and workplaces, noise levels during weekdays is equivalent to nights and weekends.
In recent days, seismologists have seen seismic noise levels pick up again in cities around the globe. Some countries have officially reduced the restrictions on regular daily lives, but in other places there is seismic evidence of society slowly running out of patience with the strict rules of lock-downs. In the figure below, you can see this does not appear the case for New Zealand: data from a seismometer in a borehole in Herne Bay shows the noise levels in the city of Auckland remain much lower than before the lock-down. Kia Kaha, Tamaki Makaurau!