As well
known, each type of seismic waves has a specific particle motion. The basic
surface waves Love and Rayleigh show the particle motions polarized linearly in
the transversal-horizontal plane and elliptically in the vertical-radial plane,
respectively. Like in the body waves, polarization properties can be used to
design the surface wave discrimination filter. The process consists of
weighting the amplitudes of vertical (Z),
radial (R) and tangential (T) components of the ground motion at
each frequency according to the particle motion. The weighting process is
applied to entire length of each component for selected window length and
moving interval, but weights are not applied to the original phase values. The
weighted parts for each window are transformed to the time domain and filtered
signals are obtained as the arithmetic average of values of the overlapping
points. The method has been applied to the broad-band
digital three-component records at stations having about 10° epicenter
distances of Bogazici University Kandilli Observatory and Earthquake Research
Institute (KOERI) of Erzurum earthquakes and noticed that the window length and
moving interval in proportion to epicenter distance affect the results on a
large scale. For the cases in which the best results are obtained, it has been
determined that the ratio between the window length and moving interval for
increased epicenter distances are 3.95, 4.5 and 4.8, respectively.
Cite this paper
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