The effect of confinement due to COVID-19 on seismic noise in Mexico

Abstract:

The world began the year 2020, facing the pandemic of COVID-19, the disease caused by the SARS-Cov2 coronavirus. Governments implemented strategies that have involved confinement in our homes to contain the rapid transmission of the virus, reducing our mobility and thus spreading the virus. Reduction on mobility has been reflected in a decrease in seismic noise levels in the world's seismic stations, especially in those installed in cities. In Mexico, starting on March 23, the #QuédateEnCasa campaign (#StayAtHome) began, asking the population who were not engaged in essential activities and who were in a position to do so, to stay home. The effect on seismic noise at stations in cities, especially in Mexico City, was immediate, reaching its minimum in the first week of May. However, around those dates, the Government's speech changed upon returning to the "New Normal," proposed as of May 17. Although there was no relaxation in the confinement measures in several cities, an increase in seismic noise began to manifest. The levels continued to rise, showing fluctuations and, in general, without returning to normal levels in places like Mexico City. On the other hand, in some stations, a decrease related to human activity was not observed, but an increase was even seen.

In this work, we explore seismic noise levels' relationship with the confinement measures implemented by the state governments and the active cases of COVID-19 at the sites where the seismic stations are located. We also explore the correlation with various aspects of seismicity, such as the perception of movement by small to moderate earthquakes, as well as statistics in the catalog of the National Seismological Service.