Abstract
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. 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 represent the wide geographical
spread of Canada. The source of data for the study was seismic stations
run by the Canadian National Seismograph Network (CNSN). Data available
freely on the Incorporated Research Institutions for Seismology (IRIS)
website was used. Python and ObsPy were used to load and convert raw
data into Probabilistic Power Spectral Densities (PPSDs). The seismic
vibrations in the PPSDs that fell between 0.1 HZ and 20 HZ were
extracted and averaged for every two weeks period to determine the trend
of seismic vibrations. The lockdown had an impact on seismic vibrations
in almost all the cities I analyzed. Except for Ottawa, the seismic
vibrations decreased between 14% - 44% with the biggest decrease in
Yellowknife in the Northwest Territories. In the 3 densely packed cities
of the population over 1 million - Toronto, Montreal, and Calgary, the
seismic vibrations dropped by over 30%. In the case of Ottawa, the
seismic vibrations increased by 8%. 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. Finally, a comprehensive online training module was created
using Jupyter notebooks to allow researchers to analyse lockdown data
from other seismic stations.