The present disclosure provides embodiments seismic energy sources configured to generate enhanced shear wave energy in order to more accurately determine the distribution and orientation of fractures in subterranean formations. At least one seismic energy source includes an elongate rod having a first end and a second end, a detonator coupled to the first end, and a bull plug coupled to the second end. An explosive is helically-wrapped about the elongate rod continuously from the first end to the second end and configured to detonate such that a time-delayed detonation is achieved which induces increased shear wave energy in the surrounding formations.