According to some embodiments, a borehole deployable apparatus is described that can be used to generate strong vibrations in a subterranean rock formation. In some embodiments, the apparatus accelerates a mass using mechanisms built into the tool and causes the mass to strike the borehole wall. The mechanisms can control the mass acceleration, and the frequency of strikes. In some embodiments, the apparatus is designed for use in the field of petroleum recovery where the vibrations are used to create or re-establish a flow rate for the fluids in the formation.