Guidocorona - seismic vibrations are the energetic waves that travel along the surface of the Earth that are produced by movement of the Earth's crust, especially along fault lines -- not only earthquakes, but less intense, continuous motion ("microseismic" activity). These seismic waves have transverse, perpendicular and rotational components (forces) capable of travelling long distances with great rapidity.
The seismic wave acts on a building much like a wave on the ocean passing under a boat -- when the wave passes under it, it forces the boat to move up and down, also pushes the boat forward and back and rocks it to and fro.
For convenience, we often include under the heading "seismic vibration" other sources of low-frequency vibration: automobiles, trucks and buses; trains and subways; the effect if tides around coastal areas, the effect of wind on high rise buildings (sway), even low frequency vibration produced by large applicances in the building -- large fans, A/C, etc.
The seismic wave acts on a building much like a wave on the ocean passing under a boat -- when the wave passes under it, it forces the boat to move up and down, also pushes the boat forward and back and rocks it to and fro.
For convenience, we often include under the heading "seismic vibration" other sources of low-frequency vibration: automobiles, trucks and buses; trains and subways; the effect if tides around coastal areas, the effect of wind on high rise buildings (sway), even low frequency vibration produced by large applicances in the building -- large fans, A/C, etc.