SEISMOGRAPH Russian patent published in 2003 - IPC

FIELD: seismology. SUBSTANCE: invention is related to means registering horizontal vibrations of ground generated by seismic waves from sources of natural and artificial origin. Given facility includes horizontal seismograph with extended arm of pendulum with magnet on its end and fragment of magnetically soft cylindrical surface of revolution with radius somewhat larger than radius of rotation of pendulum attached to body and installed beneath magnet. Axis of cylindrical surface coincides with axis of swinging of pendulum. EFFECT: increased period of own vibrations of pendulum system that is essential for registration of movement of ground emerging with passage of seismic waves. 2 dwg