The Ballard Borehole Seismic Source is a tool designed to enable engineering geophysicists and geotechnical engineers to conduct high quality P- and S-wave crosshole tests in accordance with ASTM standards.

Unlike P-wave energy which appears first on a seismic record, S-wave energy must be enhanced to be positively recognized within existing wave trains. This can be best accomplished by a reverse polarity seismic source rich in S-wave energy. Since the polarity of an S-wave can be controlled (unlike the P-wave) the seismic source can provide a positive identification if it is capable of S-wave phase reversal. 

The Ballard Borehole Seismic Source is designed to offer S-wave enhancement, S-wave phase reversal, suppressed (but adequate) P-wave energy, light weight, signal repeatability, high frequency (fast rise time), maximum reliability, and low cost. An inflatable sidewall anchor system provides positive borehole clamping. A single three-in-one, 0.5 inch diameter cable houses the controls for reversible spring loaded hammer activation, zero-time geophone and air for the clamping mechanism.