Comprehensive analysis of seismic ambient noise in the Indian subcontinent

This study investigates seismic ambient noise characteristics in the Indian subcontinent, focusing on cultural noise (CN) and microseism noise (MS). Analysis of MS noise is crucial for understanding climate change and oceanic activity. Characterization of the CN band is also important for imaging the earth's crustal structure. We use the data from 10 stations of the Indian network in the Indian subcontinent. Seismic ambient noise has been assessed across the continent's northern, southern, eastern, and western regions. We have applied the frequency-dependent polarization analysis technique to estimate the power spectral density (PSD). To understand the noise source, we have conducted the polarization analysis that detects polarized signals based on the instantaneous degree of polarization (DOP). The results show that CN has the strongest amplitude depicting clear diurnal variations. We notice the seasonality in the amplitude, source direction, and quantity of polarized signals in the MS band. Furthermore, the impact of tropical cyclones on the amplitude spectra of the MS band is quite evident in our analysis. Moreover, the southwest monsoon significantly influenced the distribution of MS noise across the subcontinent.