Zusammenfassung
In a pilot vertical seismic profiling study, P-wave and cross-polarized
S-wave vibrators were used to investigate the potential utility of
shear-wave anisotropy measurements in characterizing a fractured
rock mass. The caprock at The Geysers geothermal field was found
to exhibit about an 11 percent velocity variation between SH-waves
and SV-waves generated by rotating the S-wave vibrator orientation
to two orthogonal polarizations for each survey level in the well.
The effect is generally consistent with the equivalent anisotropy
expected from the known fracture geometry.
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