Preprints
https://doi.org/10.5194/se-2021-38
https://doi.org/10.5194/se-2021-38

  26 May 2021

26 May 2021

Review status: a revised version of this preprint was accepted for the journal SE and is expected to appear here in due course.

The effect of 2020 COVID-19 lockdown measures on seismic noise recorded in Romania

Bogdan Grecu1, Felix Borleanu1, Alexandru Tiganescu1,2, Natalia Poiata1,3, Raluca Dinescu1, and Dragos Tataru1 Bogdan Grecu et al.
  • 1National Institute for Earth Physics, Magurele, 050811, Romania
  • 2Technical University of Civil Engineering Bucharest, Bucharest, 020396, Romania
  • 3Université de Paris, Institut de Physique du Globe de Paris, CNRS, F-75005 Paris, France

Abstract. After the World Health Organization declared COVID-19 a pandemic in March 2019, Romania followed the example of many other countries and imposed a series of restrictive measures, including restricting people's mobility and closing social, cultural and industrial activities to prevent the spread of the disease. In this study, we analyze continuous vertical component recordings from the stations of the Romanian Seismic Network – one of the largest networks in Europe containing 148 stations – to explore in detail the seismic noise variation associated with the reduced human mobility and activity in Romania due to COVID-19. We focused our investigation on four frequency bands – 2–8 Hz, 4–14 Hz, 15–25 Hz and 25–40 Hz – and found that the largest reductions in seismic noise associated with the lockdown corresponds to the high frequency range, from 15 to 40 Hz. We found that all the stations with large reductions in seismic noise (> ~40 %) are located inside and near schools or in buildings, indicating that at these frequencies the drop is related to the drastic reduction of human activity in these edificies. In the lower frequency range (2–8 Hz and 4–14 Hz) the variability of the noise reduction among the stations is lower than in the high frequency range, and the noise level is reduced by up to 35 %. This drop is due to reduced traffic during the lockdown, as most of the stations showing such changes in seismic noise in these bands are located within cities, near main or side streets. In addition to the noise reduction observed at stations located in populated areas, we also found seismic noise lockdown-related changes at several stations located far from urban areas, with movement of people in the vicinity of the station explaining the noise reductions. Apart from the opportunity to investigate in more detail the seismic noise characteristics due to human mobility and activity, we show that noise reduction during the lockdown has also improved the earthquake detection capability of the accelerometers located in noisy urban environments.

Bogdan Grecu et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on se-2021-38', Anonymous Referee #1, 29 Jun 2021
    • AC1: 'Reply on RC1', Bogdan Grecu, 10 Aug 2021
  • RC2: 'Comment on se-2021-38', Anonymous Referee #2, 29 Jun 2021
    • AC2: 'Reply on RC2', Bogdan Grecu, 10 Aug 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on se-2021-38', Anonymous Referee #1, 29 Jun 2021
    • AC1: 'Reply on RC1', Bogdan Grecu, 10 Aug 2021
  • RC2: 'Comment on se-2021-38', Anonymous Referee #2, 29 Jun 2021
    • AC2: 'Reply on RC2', Bogdan Grecu, 10 Aug 2021

Bogdan Grecu et al.

Data sets

RO: Romanian Seismic Network National Institute for Earth Physics https://doi.org/10.7914/SN/RO

Model code and software

SeismoRMS - A simple python/jupyter notebook package for studying seismic noise changes (Version 1.0) T. Lecocq, F. Massin, C. Satriano, M. Vanstone, and T. Megies https://doi.org/10.5281/zenodo.3820046

Bogdan Grecu et al.

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Short summary
The lockdown imposed in Romania to prevent the spread of COVID-19 has significantly impacted the human activity across the country. By analyzing the ground vibrations recorded at seismic stations, we were able to monitor the changes in human activity before and during the lockdown. The reduced human activity during the lockdown has also provided a good opportunity for stations sited in noisy urban areas to record earthquake signals that would not have been recorded under normal conditions.