Abstract: A method is described for controlling the magnetic field strength of an electromagnetic geophone by: a) providing a specified center value each for a geophone sensitivity parameter and a geophone damping parameter; b) magnetizing an electromagnetic geophone to full saturation of the magnet; c) measuring the value each for the fully saturated geophone sensitivity parameter and damping parameter; d) partially demagnetizing the geophone; e) measuring the value each for the partially demagnetized geophone sensitivity and damping parameters; f) calculating a slope for a geophone demagnetization line representing geophone demagnetization versus demagnetizing force by utilizing the measured fully saturated geophone sensitivity and damping parameters as one point on the line and utilizing the measured partially demagnetized geophone sensitivity parameter and damping parameter as another point on the line; and g) calculating an amount of demagnetization required to provide the geophone with sensitivity and damping par