Quote:
Originally Posted by Bill Douglas
Yes, it's layers of lead and rubber making up the foundations. The idea is to stop the jolt from earthquakes. The building boogies about because the ground is moving, but the sudden stop from the ground moving down the up, or left then right, has been softened.
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There's an interesting version, which is a big ass swimming pool on the roof. The mass of free water will create a 2-arm pendulum effect, which has a higher frequency but lower amplitude. Eventually the water gets into sync with the building vibrations, but out of phase, thus reducing them. There are a couple of designs, called "tuned mass dampers". I think the swimming pool one ended up being an accident.