Elastic rebound in an earthquake. Artwork of the surface displacement of the earth according to the elastic rebound theory of earthquake formation. At top, a straight fence separates crops from soil. The region is on a fault between two plates, which are pushed in the directions shown by the large orange arrows (second diagram). Friction between the plates stops them moving, but the pressure deforms the land, bending the fence. Once the pressure exceeds the frictional force, an earthquake occurs, and the plates rapidly move past each other (red arrows, third diagram). This release (rebound) of stored elastic energy leaves the plates displaced (bottom) from their previous position. The San Andreas fault in California, USA, is a fault like this.