A Simple Mechanical Impact System (SMIS) was developed recently as a non-explosive seismic source. The SMIS consists of an impact head, a steel rod with extensions, and an anchoring system. The system is small and simple, and can be conveniently installed in a shallow borehole oriented in any direction. The SMIS was developed to address two problems commonly associated with non-explosive seismic sources: insufficient seismic strength and lack of repeatability. Field tests have shown that it is possible to produce clear and repeatable signals with this system even when the SMIS is installed in a coal seam.