Diurnal seismic ambient noise and seismic station performance characterization in the Bengal Basin, Bangladesh

Abstract

Seismic ambient noise (SAN) energy can potentially blur regional and teleseismic arrivals as well as various microearthquakes at specific frequencies. Therefore, quantification of the SAN energy level in a region is required to optimize seismic station distribution for seismological investigations. Moreover, evaluation of station performance and noise source is possible from observation of SAN energy levels. The SAN energy distribution from seismic stations in the Bengal Basin (BB), Bangladesh has not yet been estimated. At the same time, this tectonically active and complex region is less studied using seismic methods. This study aims to quantify SAN energy and characterize its diurnal variation along with evaluating station performance at 11 seismic stations, which were temporarily installed in the deeper portion of the BB. Herein, the daily SAN energy level was determined within the period range of 0.02–30 s by estimating the power spectral density (PSD) of seismic data for 7 continuous days. SAN energy and its variation over time were observed using the probability density functions (PDFs) of PSDs and spectrograms, respectively. The sources of SAN energies at different period bands were also investigated by comparing the PSDs with daily variations in human activities, nearby noise sources, local meteorological factors (i.e., air temperature and precipitation), and sea level height. The insights from this study could be useful for the future deployment of seismic networks as well as seismological studies in the BB.