Abstract
We present a method to extract seismic signals from three-component
array data and estimate their polarization properties at each station.
The technique is based on a singular value decomposition (SVD) of
the complex three-component analytic signal and applies to linearly
as well as elliptically polarized seismic phases. To increase accuracy
we simultaneously analyze data from different stations and apply
a noise weighting based on prearrival data. For polarization analysis,
an automated routine is also included. The automated routine selects
the data window with the best signal-to-noise ratio from which to
obtain a polarization. A linearity measure and a confidence interval
accompany the polarization estimate at each station in the array.
We test our technique for automated polarization analysis on synthetic
P-wave data and compare results with those from other methods. A
microseismic dataset from the North Sea provides a unique opportunity
to statistically compare previous and independently obtained P-wave
polarizations with those provided by the automated technique presented
here. We conclude that, for P-wave polarization analysis, our method
is robust and significantly more accurate than conventional, mainly
manual methods. This is especially so on data with polarized and
correlating background noise. It is also faster and provides meaningful
quality estimates. 10.1785/0120050235
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