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

Abstract

ABSTRACT. Recent studies have shown that urban ambient noise (UAN) decreased at many sites due to a slowdown in human activities brought by the SARS-CoV-2 (COVID-19) pandemic lockdowns. Such understanding is inferred from the historical record of the noise levels, which may also help us disambiguate noise sources as required for ambient noise tomography, microseismic and other seismic based studies. As UAN is site-specific, and its analysis enables passive situational awareness, therefore, in the present study, we analyzed the temporal variations in UAN before, during and after the social isolation in the metropolitan region of Lima, the capital of Peru, for the very first time. We used continuous waveforms recorded from February 1st to August 31st, 2020, at the Ñaña (NNA) broadband seismic station for the analysis. Results show the temporal changes occur in different frequency ranges; for example, at frequencies >1 Hz, significant changes in the mean daytime amplitudes are observed, which are absent in the lower frequency range (0.1–1, 1–3, 3–5 Hz). A maximum noise reduction of 37% is observed and should be considered for any future application of UAN. The results were verified by comparing with Community Mobility Reports (CMR) provided by Google using statistical change-point analysis.