4950 20241203105127.0 10.1126/science.abd2438 DOI SCART-2020-0142 Lecocq, T. Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures 2020 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. NO Hicks, S.P. Van Noten, Koen van Wijk, K. Koelemeijer, P. De Plaen, R.S.M. Massin, F. Hillers, G. Anthony, R.E. Apoloner, M.-T. Arroyo-Solórzano, M. Assink, J.D. Büyükakpinar, P. Cannata, A. Cannavo, F. Carrasco, S. Caudron, C. Chaves, E.J. Cornwell, D.G. Craig, D. den Ouden, O.F.C. Diaz, J. Donner, S. Evangelidis, C.P. Evers, L. Fauville, B. Fernandez, G.A. Giannopoulos, D. Gibbons, S.J. Girona, T. Grecu, B. Grunberg, M. Hetényi, G. Horleston, A. Inza, A. Irving, J.C.E. Jamalreyhani, M. Kafka, A. Koymans, M.R. Labedz, C.R. Larose, E. Lindsey, N.J. McKinnon, M. Megies, T. Miller, M.S. Minarik, W. Moresi, L. Márquez-Ramírez, V.H. Möllhoff, M. Nesbitt, I.M. Niyogi, S. Ojeda, J. Oth, A. Proud, S. Pulli, J. Retailleau, L. Rintamäki, A.E. Satriano, C. Savage, M.K. Shani-Kadmiel, S. Sleeman, R. Sokos, E. Stammler, K. Stott, A.E. Subedi, S. Sørensen, M.B. Taira, T. Tapia, M. Turhan, F. van der Pluijm, B. Vanstone, M. Vergne, J. Vuorinen, T.A.T. Warren, T. Wassermann, J. Xiao, H. Science 2020 thomas.lecocq@observatoire.be https://science.sciencemag.org/content/early/2020/07/22/science.abd2438 https://github.com/ThomasLecocq/2020_Science_GlobalQuieting https://github.com/ThomasLecocq/SeismoRMS 2013361 http://publi2-as.oma.be/record/4950/files/Figure2.png Global temporal changes in seismic noise. Global daily median high frequency seismic noise is depicted, normalized to percentage variation of the baseline before lockdown measures and sorted by lockdown date. Each line of the image corresponds to one seismic station. Data gaps are shown in white. Location and country code are indicated for each station; see fig. S1 for network and station codes 26012 http://publi2-as.oma.be/record/4950/files/Figure2.jpg?subformat=icon-180 icon-180 Global temporal changes in seismic noise. Global daily median high frequency seismic noise is depicted, normalized to percentage variation of the baseline before lockdown measures and sorted by lockdown date. Each line of the image corresponds to one seismic station. Data gaps are shown in white. Location and country code are indicated for each station; see fig. S1 for network and station codes 40854 http://publi2-as.oma.be/record/4950/files/Figure2.gif?subformat=icon icon Global temporal changes in seismic noise. Global daily median high frequency seismic noise is depicted, normalized to percentage variation of the baseline before lockdown measures and sorted by lockdown date. Each line of the image corresponds to one seismic station. Data gaps are shown in white. Location and country code are indicated for each station; see fig. S1 for network and station codes published in REFERD