Abstract: A seismic directional sensor for solid-borne sound has at least one geophone with pronounced directional characteristic. The measuring electrical vibration signals, which are obtained at different circumferential angular positions of the radial longitudinal axis of the geophone and are to be compared with one another, are correlated with the direction of a seismic ray extending at right angles to the longitudinal axis of the geophone, which is ineffective in its neural circumferential angular position.The neutral circumferential angular position is determined by the ratio of the amplitude of the measuring signals which are determined on both sides adjacent to the neutral circumferential angular position in effective circumferential angular positions of the geophone. The vibration pattern of the measuring signals is antiphase in relation to the respective other side.

Abstract: In an acoustic ground vibration detector for the detection of infrasound ground vibrations, comprising at least one three-component geophone probe, the three individual geophones of said geophone probe are electrically connected in series and act upon an operation amplifier whose output signal activates a Reed relay. The activated Reed relay switches on a sound signal transmitter which produces an audible acoustic signal for the duration of the ground vibration signal. The acoustic ground vibration detector is intended in particular for locating buried persons. Moreover, it serves to protect important objects by registering infrasound ground vibrations produced by footfall sound.