Effect of coronavirus lockdowns on the ambient seismic noise levels in Gujarat, northwest India

Ketan Singha Roy,M Ravi Kumar,Santosh Kumar,Jyoti Sharma

doi:10.1038/s41598-021-86557-9

Ketan Singha Roy, M Ravi Kumar + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-86557-9

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Abstract

The Covid-19 pandemic created havoc and forced lockdowns in almost all the countries worldwide, to inhibit social spreading. In India as well, as a precautionary measure, complete and partial lockdowns were announced in phases during March 25 to May 31, 2020. The restricted human activities led to a drastic reduction in seismic background noise in the high frequency range of 1–20 Hz, representative of cultural noise. In this study, we analyse the effect of anthropogenic activity on the Earth vibrations, utilizing ambient noise recorded at twelve broadband seismographs installed in different environmental and geological conditions in Gujarat. We find that the lockdowns caused 1–19 dB decrease in seismic noise levels. The impact of restricted anthropogenic activities is predominantly visible during the daytime in urban areas, in the vicinity of industries and/or highways. A 27–79% reduction in seismic noise ground displacement (drms) is observed in daytime during the lockdown, in populated areas. However, data from station MOR reveals a drastic decrease in drms amplitude both during the day (79%) and night times (87%) since factories in this area operate round the clock. The noise at stations located in remote areas and that due to microseisms, shows negligible variation.

Highlights

The Covid-19 pandemic created havoc and forced lockdowns in almost all the countries worldwide, to inhibit social spreading
Since the quality of data is important in seismic studies, interference of useful signals with anthropogenic noise leads to loss of precious information, in view of the difficulty in isolating seismic signals from background noise covering the same frequency range
We have clearly estimated the reduction in seismic noise during the lockdown, in the frequency range of 1 to 20 Hz that is representative of anthropogenic noise sources

Summary

Introduction

The Covid-19 pandemic created havoc and forced lockdowns in almost all the countries worldwide, to inhibit social spreading. We have fmin studied the variation in seismic noise levels using d rms values in different frequency bands between 1 and 20 Hz, to analyze the effect of anthropogenic noise during pre-, co- and post-lockdown periods.

Results

Conclusion