Abstract: An apparatus actuated by seismic vibrations and other vibrations is disclosed.A vertically or substantially vertically movable rod, a weight or mass in engagement or capable of engagement with the rod and a plurality of pivotable stays or support arms supporting the weight are provided within a housing, and held in a mechanically balanced state in their entirety. When the apparatus undergoes seismic or other vibrations, the mechanical balance is disturbed, whereupon the weight is released from the support arms and allowed to fall together with the vertically movable rod due to the gravitational force, thereby effecting the switching of a related fluid or electric circuit.