Frequency dependent polarization analysis of ambient seismic noise recorded at a broadband seismometer in the central United States

• DOI: 10.1007/s11589-010-0743-5
• Publication Date: 2010-11-02T14:48:43Z
• Authors: Keith D. Koper; Veronica L. Hawley
• Keywords: Seismometer; Microseism; Seismic Noise; Rayleigh Wave; Frequency band; Ambient noise level

We present a new approach to polarization analysis of seismic noise recorded by three-component seismometers. It is based on statistical analysis of frequency-dependent particle motion properties determined from a large number of time windows via eigenanalysis of the 3-by-3, Hermitian, spectral covariance matrix. We applied the algorithm to continuous data recorded in 2009 by the seismic station SLM, located in central North America. A rich variety of noise sources was observed. At low frequencies ( 3 Hz), Rayleigh-type energy was again dominant in the form of Rg waves created by nearby cultural activities. Analysis of the time dependence of noise power shows that a frequency range of at least 0.02–1.0 Hz (much larger than the microseism band) is sensitive to annual, meteorologically induced sources of noise.