Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures
by T. Lecocq (Royal Observatory of Belgium, Belgium), S. Hicks (Imperial College London, UK), K. van Noten (Royal Observatory of Belgium, Belgium), K. van Wijk (University of Auckland, New Zealand), P. Koelemeijer (Royal Holloway University of London, UK)R.S.M. de Plaen (Universidad Nacional Autónoma de México)F. Massin (ETH Zurich, Switzerland)G. Hillers (University of Helsinki, Finland)J.D. Assink (KNMI)O.F.C. den Ouden (KNMI)L.G. Evers (KNMI)M.R. Koymans (KNMI)S. Shani Kadmiel (KNMI)R. Sleeman (KNMI)
Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the coronavirus disease 2019 (COVID-19) pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. Although the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This quiet period provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of human activities.
Lecocq, T., S. Hicks, K. van Noten, K. van Wijk, P. Koelemeijer, R.S.M. de Plaen, F. Massin, G. Hillers, J.D. Assink, O.F.C. den Ouden, L.G. Evers, M.R. Koymans, S. Shani Kadmiel and R. Sleeman, Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures