Patent ID: 8228762

Claim:
A seismic energy source, comprising: a base plate and a top block fixedly coupled in a frame, the baseplate configured for contact with a part of the Earth's subsurface to be seismically energized, the frame having associated therewith a first electromagnet assembly comprising a first electromagnet; a second electromagnet disposed in a travelling reaction mass, the traveling reaction mass movably disposed in the frame between the first electromagnet assembly and the top block, the reaction mass including at least a third electromagnet associated therewith; and circuits for selectively energizing the first, second and at least a third electromagnets, the circuits configured to energize the first and second electromagnets to repel each other such that the traveling reaction mass is lifted from the first electromagnet, the circuits configured to energize the at least a third electromagnet after a selected delay time to cause magnetic attraction between the traveling reaction mass and the top block.