Normal applications of shallow geophysical methods such as ground penetrating radar (GPR) cannot achieve significant penetration (more that a couple feet) in situations where surficial materials are highly conductive and/or cluttered with shallow pipes, wires or rebar.  Patented shear wave technology has lead to the improvement of reflection seismology to near GPR resolution. A high-resolution shear wave reflection seismic method with sufficient resolution to identify voids (or pipes) on the order of 1-foot diameter has been developed.  Key to the application of this method is a patented vibratory source capable of putting shear wave signals into the ground at frequencies ranging from 30-4000Hz at a peak force of 200 pounds.

(Left) Shear wave seismic data showing a grout-filled void. The void created subsidence beneath a highway.

(Right) The MicroVib provides high resolution high signal/noise ratios even in extremely noisy conditions.

The panel below shows voids as small as 1-foot over a concrete structure that is 7 feet below ground surface.

The MicroVib is an ideal source for surveys in areas where access is extremely limited.

A comparison of shear wave data collected with the MicroVib (left) versus data collected in the same location by a conventional, larger shear wave vibrator source.  Note the continuity of shallower events.