Abstract: A gravity gradient logging tool is used to conduct a gravimetry survey of an earth formation. A pair of piezoelectric transducers are located at spaced apart positions within the logging tool. Each transducer is loaded with a known mass and excited electrically so as to vibrate at a characteristic resonant frequency. The period of vibration of each transducer is measured as the logging tool continuously traverses the formation. The difference in the measured periods of vibration is determined as a measure of gravity gradient along the formation.