The San Andreas Fault received its name from Andrew Lawson after the 1906 earthquake. He named it for San Andreas Lake, a (now) man-modified sag pond in San Mateo county through which the fault...
The San Andreas fault is actually a "Strike-Slip" fault, which means that the movement of the plates is a side-to-side movement past each other. The Pacific plate, relatively speaking, is moving...
The San Andreas Fault is the convergent plate boundary between the North American and Pacific tectonic plates. The plates are not moving in the same direction, therefore the faulting.