Abstract: A dual mode multiple-element resonant cavity piezoceramic borehole energy source is disclosed. Thus, a source for generating detectable seismic waves in a wellbore is provided which is capable of transmitting useful signals over long distances between the source and the related receiver or receivers. A liquid-filled elongated column is provided which defines a longitudinal axis and has a resonant frequency. A resonator comprising at least one substantially cylindrical piezoelectric element having an axis approximately parallel to the axis of the borehole for inducing seismic waves in the borehole is furnished. The resonator is constructed and arranged for vibrating at the first resonant frequency, and is also constructed and arranged for vibrating at a second frequency in a hoop mode to generate seismic waves having the second frequency.