Artash Nath, Grade 9 Student, Toronto, Canada

On 7 December 2020, I gave an oral presentation about my research at the Fall Meeting of the American Geophysical Union (AGU). The AGU Fall Meeting 2020 being held online from December 1 – 17 is one of the world’s largest virtual scientific conferences. It is attended by over 25,000 delegates each year.

My oral presentation was on “The Silence of Canadian Cities: The Seismology Impact of the Covid19 Lockdown“. It was selected as the first scientific presentation for session S004 on Social Seismology: The Effect of COVID-19 Lockdown Measures on Global Seismic Noise I. If you are a registered participant at the AGU fall meeting, you can watch the oral presentation at: https://agu.confex.com/agu/fm20/meetingapp.cgi/Session/107644

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On 11 March 2020, the World Health Organization (WHO) declared Coronavirus disease (COVID-19) as a pandemic. The announcement had a cascading effect as countries around the world rushed to declare various states of emergencies. Canada was no exception. All Canadian provinces and territories implemented some health emergency measures to check the spread of COVID-19. This provided an opportunity to study the changes in seismic vibrations registered by the land-based seismic stations before, during, and after the lockdown.

The presentation was based on my research carried over several months during the school lockdown in Canada because of the COVID19. My research had 2 goals:

  • Measure the impact of COVID19 lockdown on seismic vibrations in Canada
  • Validate the sub-surface impacts with surface-level sensors and camera to measure street traffic and sound

I analyzed continuous seismic data for 6 Canadian cities: Calgary (Alberta), Edmonton (Alberta), Montreal (Quebec), Ottawa (Ontario), Toronto (Ontario), and Yellowknife (Northwest Territories).  These cities were selected as they had a seismic station nearby which was active during the lockdown and was providing live data. Furthermore these cities spread over four provinces of Canada were representation of Canada because of their physical location.

I used 9.5 billion‬ lines of seismic data points from 6 seismological stations run by the Canadian National Seismograph Network (CNSN) and the Natural Resources of Canada. The raw waveform data of several months from the seismic stations was transformed to their power spectral density (PSD) to get the intensity of vibrations over different frequencies. The seismic frequencies that were most likely due to anthropogenic signals namely in the range of 4 Hz to 20 Hz were analysed in depth. The average seismic displacement along the vertical axis was calculated for each 15-minute period for the power spectral densities data. It was then repeated for every 24 hours period in the data to get a longer term seismic vibrations trend before the lockdown and during the lockdown.

The results of my research were very interesting. In five of the six cities, Calgary, Edmonton, Montreal, Toronto, and Yellowknife there was a clear decrease in seismic vibrations. In four of these cities the reduction was over 30%.  Only Ottawa, the capital city of Canada which lies in seismically active zone, and was also the epicentre of political activities during the lockdown registered a small increase in the vibrations.

How seismic vibrations decreased in different Canadian cities

These findings based on sub-surface level seismic vibrations were validated by the ground measurements I did in Toronto to measure the traffic and street sounds during the lockdown period. The traffic levels fell by 50% while the street sounds went down by 30% during this period pointing to reduction in transportation and outdoor human activities.

As not all seismic stations were equally close to the cities, they were not equally sensitive to changes in human activities. Furthermore, while lockdown happened in all the cities selected for the study, the strictness enforced and the participation of people in the lockdown varied. Many cities extended the lockdown without any change while others extended the lockdown with a loosening of restrictions. All these differences induced variations in the study.results2

I was very happy to answer several of the questions posed after my presentation. The questions related to differences in changes in seismic vibrations in the six cities of Canada to the analysis of visual and numerical data gathered from my home made instrument.

I thank the primary convener of the session, Thomas Lecocq from the Royal Observatory of Belgium as well as the other convenors, Raphael S.M. De Plaen from National Autonomous University of Mexico, and Koen Van Noten from the Royal Observatory of Belgium for their support, guidance and encouragement. This was my first participation at the AGU meeting and I enjoyed it very much. I look forward to participating in it once again.

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