COVID-19 lockdown effects on the seismic recordings in Central America
Fecha
2021-09-30
Tipo
artículo original
Autores
Arroyo Solórzano, Mario
Castro Rojas, Diego Andrés
Massin, Frédérick
Linkimer Abarca, Lepolt
Arroyo Hidalgo, Ivonne Gabriela
Yani Quiyuch, Robin Onelio
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Resumen
A noticeable decrease in seismic noise was registered
worldwide during the lockdown measures implemented
in 2020 to prevent the spread of COVID-19. In Central America,
strong lockdown measures started during March of 2020.
In this study, we used seismic stations from Costa Rica,
Guatemala, El Salvador, and Nicaragua to study the effects
of these measures on seismic records by characterizing temporal
variations in the high-frequency band (4–14 Hz) via
spectral and amplitude analyses. In addition, we studied the
link between the reduction in seismic noise and the number
of earthquake detections and felt reports in Costa Rica and
Guatemala. We found that seismic stations near the capitals
of Costa Rica, Guatemala, and El Salvador presented a decrease
in their typical seismic noise levels, from 200 to 140,
from 100 to 80, and from 120 to 80 nm, respectively. Our results
showed that the largest reduction of 50% in seismic
noise was observed at seismic stations near main airports,
busy roads, and densely populated cities. In Nicaragua, the
seismic noise levels remained constant ( 40 nm), as no lockdown
measures were applied. We suggest that the decrease
in seismic noise levels may have increased earthquake detections
and the number of felt reports of low-magnitude earthquakes.
However, the variations observed in several seismic
parameters before and after the lockdown are not significant
enough to easily link our observations or separate them from
other contributing factors. Our results imply that the study
of seismic noise levels can be useful to verify compliance
with lockdown measures and to explore their effects on earthquake
detection and felt reports.
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Palabras clave
Central America, Seismology, COVID-19