1. Measuring near-surface velocity with geophones or hydrophones in a borehole and a source on or near the surface. 2. Engineering seismology measurement of P-and S-wave velocities using a source at the surface and a clamped triaxial geophone in a borehole. S-wave energy is often enhanced by use of directional sources. 3. Induced-polarization method that explores the region near a drill hole using a single potential or current electrode in the drill hole and other electrodes on the ground surface. Compare in-hole IP method.