Abstract: A latching device which detects the initial shocks of major earthquakes and activates safety devices before the onset of destructive ground motions. A unidirectional vertical threshold seismoscope is integrated with mechanical and electromechanical safety devices to latch cabinets closed, secure movable objects, shut off gas, water, and electric utilities, activate alarms, early warning networks, and related automated response systems. The device is fully self contained, requires no external power, and is virtually impervious to nonearthquake noise in that it is designed to respond specifically to the vertical acceleration and displacement characteristic of the initial shock waves of a major earthquake.