The VBS-2 Vibrating Wire Stress Meter measures stress changes in elastic rocks. The Stress meter is a high strength steel-proving ring wedged tightly across one diameter inside a borehole drilled into a rock. Distortion, caused by changing rock stress, is measured by means of a vibrating wire that is tensioned across the diameter. Changes in rock stress cause changes in the resonant frequency of vibration of the tensioned wire. Installed in boreholes up to 100 feet long. Diamond drill holes are preferable.

The transducer uses a shaft coupled to a spring, which in turn, is coupled to a vibrating wire element. Movement of the shaft changes the tension in the spring and in the wire causing a corresponding change in its frequency of vibration.