Temporal changes in anthropogenic seismic noise levels associated with economic and leisure activities during the COVID-19 pandemic

Abstract

Seismic ambient noise with frequencies > 1 Hz includes noise related to human activities. A reduction in seismic noise during the COVID-19 pandemic has been observed worldwide, as restrictions were imposed to control outbreaks of the SARS-CoV-2 virus. In this context, we studied the effect of changes in anthropogenic activities during COVID-19 on the seismic noise levels in the Tokyo metropolitan area, Japan, considering time of day, day of the week, and seasonal changes. The results showed the largest reduction in noise levels during the first state of emergency under most conditions. After the first state of emergency was lifted, the daytime noise reverted to previous levels immediately on weekdays and gradually on Sundays. This was likely because economic activities instantly resumed, while non-essential outings on Sundays were still mostly avoided. Furthermore, the daytime noise level on Sundays was strongly reduced regardless of changes on weekdays after the second state of emergency, which restricted activities mainly at night. Sunday noise levels gradually increased from the middle of the second state of emergency, suggesting a gradual reduction in public concern about COVID-19 following a decrease in the number of infections. Our findings demonstrate that seismic noise can be used to monitor social activities.

Variabilities in Urban Ambient Noise Before, During, and After Covid-19 Lockdown in the Peruvian Capital

“…A similar approach to highlighting the noise change at a particular frequency range can be seen in other related studies (e.g., Pandey et al, 2020;Poli et al, 2020;Somala, 2020;Yabe et al, 2020;Arroyo-Solórzano et al, 2021;Grecu et al, 2021;Kuponiyi and Kao, 2021;Nimiya et al, 2021;Pérez-Campos et al, 2021;Shen and Zhu, 2021). This is the frequency range where most of the day-to-day human activities occur like walking, traveling and other related cultural activities.…”

“…The variations in the hours of day and days of weeks are also analyzed by calculating ambient noise PSD so that a link between the COVID 19 and noise reduction can be established. The relative change in PSD is calculated at three different frequency ranges (3)(4)(5)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(5)(6)(7)(8)(9)(10), particularly affected by the urban activities following an approach adopted after Nimiya et al (2021). The hourly variations in noise follow a distinct pattern associated with anthropogenic activities (Nimiya et al, 2021).…”

“…The relative change in PSD is calculated at three different frequency ranges (3)(4)(5)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(5)(6)(7)(8)(9)(10), particularly affected by the urban activities following an approach adopted after Nimiya et al (2021). The hourly variations in noise follow a distinct pattern associated with anthropogenic activities (Nimiya et al, 2021). These PSD presentations show the temporal variations in UAN at different hours of the days before, during and after the COVID lockdown (Figure 5).…”

Earth-shaking J. LEAGUE supporters

“…This suggests that observing human-induced seismic waves will be useful for monitoring human activity in a stadium. As shown by the noise level decrease during the COVID-19 pandemic (e.g., Lecocq et al 2020 ; Yabe et al 2020 ; Nimiya et al 2021 ), seismometers can be a new tool for monitoring human activities in society. Observing and analyzing unique signals generated in urban environments will also be useful for assessing local shallow subsurface structural models (e.g., Quiros et al 2016 ; Lavoué et al 2020 ), which is key for improving ground shaking prediction.…”

“…In 2020, due to the COVID-19 pandemic, the noise levels of seismometers globally have decreased (e.g., Lecocq et al 2020). A clear drop in the seismic noise level due to reduced social activities was also observed in the MeSOnet (Yabe et al 2020;Nimiya et al 2021).…”