Studies of past earthquake traces on both the northern San Andreas Fault and the southern Cascadia subduction zone indicate a correlation in time which may be evidence that quakes on the Cascadia subduction zone may have triggered most of the major quakes on the northern San Andreas during at least the past 3,000 years or so . The evidence also shows the rupture direction going from north to south in each of these time-correlated events . The 1906 San Francisco earthquake seems to have been a major exception to this correlation , however , as it was not preceded by a major Cascadia quake
1906 San Francisco earthquake
1906 San Francisco earthquake
Cascadia subduction zone