The effect of 2020 Covid-19 pandemic lockdowns on seismic ambient noise recorded in Eastern Dharwar region, south-eastern India

In March 2020, after the declaration of the COVID-19 pandemic by the World Health Organization (WHO), all the countries worldwide imposed a series of restrictions on public movement, and social, cultural, and industrial activities to prevent the spread of the disease. India was no exception. As a precautionary measure, the Indian government announced a complete lockdown from zero hours on 25th March 2020. With it, a drastic reduction in seismic noise level was observed in the short- period band (0.1–1 s). The short-period band is mostly dominated by anthropogenic or cultural noise due to human activities. In this study, we have analyzed the impact of lockdown on seismic noise level using the power spectral density (PSD) at 14 broadband seismometers installed at different locations in Eastern Dharwar region, south-eastern India. The PSDs were estimated before and after the lockdown to explore the noise level variation associated with the reduced human activity and mobility. Due to the lockdowns, the reduction in the seismic noise is observed in the level of 2–20 dB. Also, the obtained noise reduction is more in stations located in rural areas than the stations located in urban areas. We have observed a significant reduction in cultural noise and negligible reduction in microseismic noise level at all the stations.