Transcurrent Fault (Strike-Slip Fault)

Probably the most well known and well studied fault is the transcurrent (strike-slip) fault known as the San Andreas fault of California. This fault marks the margin line between the Pacific and North American Plates. Movement on a strike strip fault is generally horizontal. On the surface, scarps form as hills crossing the fault zone are torn apart by movement over time. Actually anything crossing this fault zone is either slowly torn apart, or offset. Rivers crossing the fault line are called offset streams and are classic signatures of fault activity along the San Andreas. These faults can be very long, the San Andreas is nearly 600 miles long.

The Reverse Fault

The reverse fault is a normal fault except the general movement of the fault blocks is toward

each other, not away from each other as in the normal fault. This forms a thrust fault type expression on the surface with material overlaying other material.

The Normal Fault

The normal fault is not necessarily normal in the sense that it is common....because.... it is not the most common of faults. However what is normal about them is that their movement tends to follow the gravitational pull on the fault blocks involved. The fault plane on the normal fault is generally very steep. In a normal fault the two involved blocks are (by gravity) pulling away from one another causing one of the fault blocks to slip upward and the other downward with respect to the fault plane (it is hard to determine whether both or just one block has moved.). The exposed upward block forms a cliff-like feature known as a fault scarp. A scarp may range from a few to hundreds of meters in height and their length may continue for 300 or more kilometers (around 200 miles).