EARTHQUAKE-ACTIVATED SHELF SECURITY SYSTEM

An earthquake-activated shelf security system has two guide rails attached to both sides of a shelf or pallet rack. At least one retainer is moveably constrained to move along the guide rails by a rotating loop located on each end of the retainer. The guide rail has a retainer rest portion and allows the retainer to rest in a prepared configuration without moving down the rail unless acted upon by a shaking event such as an earthquake. A movable backstop is located along a back portion of the retainer rest portion. The position of the rest stop can be adjusted to adjust the sensitivity of the system to earthquakes. The guide rails have retainer stops located at selected positions to keep the retainer from moving past. In one embodiment two retainers are provided and in another embodiment, a mesh is provided to contain items that would otherwise fall through.