foundation

In an earthquake, the release of energy in the Earth’s crust creates seismic waves, or waves of force, that spread out from the energy release center, or epicenter.  As a wave passes an object on the ground, the ground and object move with the wave a short distance and then spring back, only to be hit by another wave, and another, and another.  This massive shifting of the ground puts great lateral stress on objects such as buildings.  As the stress on the structures that make up the building accumulates, the building eventually fails in numerous locations.  For a small-scale example, glue a cardboard house to another piece of cardboard and then shake it back and forth.  The weakest part of the house (probably the glue in this example) will fail and the house will fall over.  When Earthquakes are powerful enough, they create massive damage to cities such as what happened in Haiti.  Read more... (356 words, 3 images, estimated 1:25 mins reading time)