The San Andreas fault zone has been a very significant source of major California earthquakes. From 1812 to 1906 it generated four major earthquakes of M ~7 or larger in two pairs on two major portions of the fault. A pair of major earthquakes occurred on the central to southern region, where the 1857 faulting overlapped the 1812 earthquake faulting. A pair of major earthquakes occurred on the northern region, where the 1906 faulting overlapped the 1838 earthquake faulting.
