A vibration sensor that detects seismic ground motion and commands the elevator to immediately move to the nearest landing and open its doors.
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Seismic switches monitor building acceleration in the horizontal plane. When the detected vibration exceeds a preset threshold — typically divided into P-wave (early warning) and S-wave (main shock) sensitivity levels — the controller commands the car to travel at reduced speed to the nearest landing, open doors, and park out of service. This protects passengers from becoming trapped between floors and prevents derailment of guide shoes from rails damaged by the quake. EN 81-77 provides comprehensive requirements for elevators subject to seismic conditions, covering guide rail strength, buffer anchoring, and rope-jump prevention devices.
