1. A method for selecting a location for extracting minerals comprising the steps of: (a) prospecting a target mining area to investigate subsurface structures; (b) measuring, at predetermined locations, seismic signals that represent reflections of seismic energy by subsurface structures and interfaces; (c) from the measured seismic signals, synthesizing seismic data representing signals measurable at locations other than said predetermined locations, thereby obtaining a more dense representation of the subsurface structures and interfaces; and (d) using said seismic traces and said synthesized seismic data to select a mining location.