PRELIMINARY REPORT ON A SINGLE-CHANNEL STATISTICAL TECHNIQUE FOR SUPPRESSING LONG-PERIOD MICROSEISMIC NOISE.
GEOTECH GARLAND TX
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The probability distribution of the sample power of long-period microseismic noise at any frequency can be represented as that of a scaled chi-square variable. A computer program has been written which estimates the upper 90 percent probability limit on this distribution for a series of discrete frequencies representing the long-period spectrum, from a set of sequential samples of the noise. Subtraction of these upper 90 percent limits from the spectra of subsequent data samples results in a substantial improvement in the time-domain signal-to-noise ratios of any transient Rayleigh wave signals in the subsequent samples. Examples demonstrating the effectiveness of the technique are presented. Author