Borehole Geophone
Systems
GeoSurvey Systems offers a selection of wall-lock borehole geophones.
Model BHG-2 (pictured on the right in photograph) contains a 3-component
geophone in an X-Y-Z orientation. The outside diameter is 1.85 inches (47
mm), small enough to fit inside a schedule-40, 2-inch plastic pipe. The
clamping mechanism is a robust, steel spring compressed by a DC electric
motor. There are no rubber bladders to break or tubes to leak, and
operation is relatively independent of depth. BHG-2 models have been used
to depths of 500 meters (consult factory for details). Geophone elements
are available with 10, 14, 28 or 40 Hz natural frequencies.
