Earthquake detection and alarm unit and system

A vertical motion detection and alarm unit for detecting vertical motion comprising:

• a frame having an upper side and a lower side, attached or placed on the ground or a structure to be monitored;
• an upper rocker connected on said upper side by an upper axis and a lower rocker connected on said lower side by a lower axis, wherein
• said upper rocker and said lower rocker are capable of pivoting about said upper axis and said lower axis, respectively, with respect to said frame,
• wherein the upper axis and the lower axis are parallel and horizontal to each other, and
• wherein said upper rocker has an upper counter weight at a distance from the upper axis and said lower rocker has a lower counter weight at a distance from the lower axis;
• a pipe having an upper end and a lower end and a weight freely moving within the pipe and connected to the upper end with a spring, the pipe being connected between said upper rocker and said lower rocker, such that:
• the upper end is connected to said upper rocker with an upper pivot, at a distance from and on an opposite side from the upper counter weight, and
• the lower end is connected to said lower rocker with a lower pivot, at the distance and opposite to the lower counter weight;
• wherein said upper counter weight and said lower counter weight balance the upper rocker and the lower rocker against the weight in the pipe;
• a lower needle connected to the lower rocker and pointing substantially vertically towards the upper rocker;
• an adjustable resilient member connected to said lower side of the frame, and inserted to a cavity within said lower rocker;
• a trigger mechanism connected to said upper rocker wherein the trigger mechanism comprises a spring-loaded upper needle, wherein in an armed state, a distal end of said spring-loaded upper needle rests on a distal end of said lower needle, and
• wherein relative motion between the distal end of said lower needle and the distal end of said spring-loaded upper needle activates said trigger mechanism by allowing the spring-loaded upper needle to be pushed by the spring to an activated position;
• and
• a switch coupled to said spring-loaded upper needle is capable of producing an alarm signal when said spring-loaded upper needle moves to its activated position,
• wherein a vertical motion of said frame causes said upper rocker and said lower rocker to rotate thus activating said trigger mechanism, and
• wherein changing the length of said resilient member changes a magnitude of said vertical motion that is required to activate said trigger mechanism.