Intrinsic noise level of noise cross-correlation functions and its implication to source population of ambient noises
Journal
Geophysical Journal International
Journal Volume
209
Journal Issue
1
Pages
141-151
Date Issued
2017
Author(s)
Abstract
We present a quantitative procedure to evaluate the intrinsic noise level (INL) of the noise cross-correlation function (NCF). The method is applied to realistic NCFs derived from the continuous data recorded by the seismic arrays in Taiwan and Korea. The obtained temporal evolution of NCF noise level follows fairly the prediction of the theoretical formulation, confirming the feasibility of the method. We then apply the obtained INL to the assessment of data quality and the source characteristics of ambient noise. We show that the INL-based signal-to-noise ratio provides an exact measure for the true noise level within the NCF and better resolving power for the NCF quality, and such measurement can be implemented to any time windows of the NCFs to evaluate the quality of overtones or coda waves. Moreover, since NCF amplitudes are influenced by both the population and excitation strengths of noises, while INL is primarily sensitive to the overall source population, with information from both measurements, we may better constrain the source characteristics of seismic ambient noises.
SDGs
Type
journal article