
TY  - JOUR
A1  - Squire, S.G. 
A1  - Hillis, R.R. 
A1  - Rutty, M.J. 
T1  - Hammer-induced seismic investigations in an area of observed anisotropy
JF  - Exploration Geophysics
JO  - Explor. Geophys.
Y1  - 1995
VL  - 26
IS  - 3
SP  - 202
EP  - 205
KW  - 
UR  - https://doi.org/10.1071/EG995202 
N2  - A seismic experiment was undertaken in order to investigate the effect of an observed (outcropping) fracture set on shear-wave propagation, and more specifically whether the observed fracture set induced shear-wave birefringence. The source for the experiment was a hammer swung to impact horizontally on a source block coupled to the ground by two large metal pins. Eight three-component geophones recorded arrivals up to 40m offset from the hammer source. Impacts of opposite polarity in the in-line and cross-line direction were differenced in order to maximise S-wave, and minimise P-wave energy. After vector gain, filtering and rotation of the recorded data into in-line and cross-line directions, Alford rotation was undertaken on selected windowed events in order to detect shear-wave birefringence. In-line and cross-line energy is maximised by a co-ordinate rotation to the north?south direction, parallel to the observed fracture direction, suggesting that the observed fracture direction results in an anisotropy that induces shear-wave birefringence. 
ER  -

