How Earthquakes Make Buildings Vibrate 1 - Introduction

Every building has its own fundamental frequency. If the ground below the building started to shake to and fro at the buildings natural frequency, it would cause the building to vibrate very strongly. This is known as resonance.

If the ground vibrated at a different frequency, the building would not vibrate as strongly. In fact the building's vibrations get much smaller, as the frequency of shaking moves further away from the natural frequency of the building.

When the ground shakes during an earthquake, it does not have one frequency of vibration, but it is made up from a mixture of frequencies. A building will vibrate more strongly when any of those frequencies are close to its fundamental frequency.

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Vibrating Buildings
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from Bristol University