The San Andreas Fault is actually a fault system made up of many interconnected faults that stretch across California.
It marks the boundary between the Pacific Plate and the North American Plate, with the plates moving horizontally past each other.
The plates along the San Andreas Fault move at an average rate of about 1.3 inches (33 millimeters) per year.
The fault extends approximately 800 miles (1,287 kilometers) through California, from the Salton Sea in the south to Cape Mendocino in the north.
The San Andreas Fault was responsible for the great 1906 San Francisco earthquake, which devastated the city and led to over 3,000 deaths.
The fault passes through some scenic and geologically significant areas, including the Carrizo Plain, where the fault's trace is clearly visible.
It is considered one of the most dangerous fault lines in the world due to the high population density in areas it traverses, including Los Angeles and San Francisco.