What is the elastic rebound theory?
Following the great 1906 San Francisco earthquake, Henry Feilding Reid examined the displacement of the ground surface around the San Andreas Fault. From his observations he concluded that the earthquake must have been the result of the elastic rebound of previously stored elastic strain energy in the rocks on either side of the fault. In an interseismic period the earth’s plates (see plate tectonics) move relative to each other except at most plate boundaries where they are locked. Thus if a road is built across the fault as in the figure panel Time 1 it is perpendicular to the fault trace at the point E where the fault is locked. The far field plate motions (large arrows) cause the rocks in the region of the locked fault to accrue elastic deformation, figure panel Time 2. the deformation builds at the rate of a few cm per year, over a time period of many years. When the accumulated strain is great enough to overcome the strength of the rocks an earthquake occurs. During the earthquak
