The San Andreas FAULT is a continental transform FAULT that extends roughly 1, 200 kilometers (750 miles) through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal). The FAULT divides into three segments, each with different characteristics and a different degree of earthquake risk. The San Andreas FAULT is one of the most studied faults in the world and has been the source of some of the largest earthquakes in California's history.