In geology, a fracture in the rocks of the Earth's crust, where compressional or tensional forces cause the rocks on the opposite sides of the fracture to be displaced relative to each other.
Faults range in length from a few inches to hundreds of miles, and displacement may also range from less than an inch to hundreds of miles along the fracture surface (the fault plane). Most, if not all, earthquake s are caused by rapid movement along faults. Faults are common throughout the world. A well-known example is the San Andreas Fault near the western coast of the U.S. The total movement along this fault during the last few million years appears to have been several miles.