抄録
A shear wave generator which can operate at an arbitrary depth in a borehole is developed. This generator consists of a power supply and an electrode device. The device is composed of a steel pipe with a small slit along its generatrix and of a pair of discharge electrodes. Between the electrodes, an impact is generated by high-voltage discharge, which acts on the wall of borehole through the slit in the pipe. The impulsive force is a horizontal single force superposed on a center of expansion. The wave energy sent out from a center of expansion can be reduced by covering the pipe except for the slit with an absorber. The horizontal single force radiates effective SH waves, which can be observed by transversely sensitive geophones located in the direction perpendicular to that of the slit.
