Earthquakes are the shaking of the earth’s surface caused by the earth’s rocky outer layer. Earthquakes occur because of the energy stored within the earth. It is usually due to the strain within the rocks that is suddenly released.
It can happen when two plates rub together. The plates travel in different directions and at different speeds. If one plate is slowly forced underneath the other, pressure builds up until the plates rip a part. This is the process causes the ground to move and called an earthquake.
The damage an earthquake causes depends on where it is and the time it is happening. The size will vary from small to large. Earthquakes can deform the ground, make buildings and other structures collapse, and creates tsunamis (which means large sea waves.) Every year there are several million small earthquakes.