Standing 296 meters tall above Tokyo Bay, the Yokohama Landmark Tower sits directly in one of the most seismically active and typhoon-prone zones on Earth. To maintain structural integrity and ensure occupant comfort during high winds and major earthquakes, the skyscraper relies on a sophisticated active mass damper (AMD) system installed near its top on the 71st floor. Designed by Mitsubishi Heavy Industries, the system consists of two independent 170-ton pendulum masses that act as dynamic counterweights.
Unlike passive tuned mass dampers—such as the famous 660-ton sphere in Taipei 101 which relies solely on gravity and fluid dampers—the Yokohama system is active. High-precision accelerometers throughout the tower detect sway within milliseconds. Computer algorithms calculate the dynamic forces and instruct powerful servomotors to actively drive the heavy weights on tracks in the opposite direction of the building's movement.
By actively shifting the center of gravity, the system neutralizes up to 50 percent of wind sway and significantly reduces peak accelerations from earthquake ground motion. The dual-axis motorized control allows response to complex rotational swaying patterns, preventing structural fatigue and stopping nausea-inducing motion for occupants on upper floors.