Main Menu >  Plate Tectonics and Volcanoes  >  San Andreas Fault >  5:12 A.M., April 18, 1906 With 45 seconds of intense shaking, the Pacific Plate lurched 6 m (20 ft) northward relative to the North American Plate, and an unsuspecting city was jolted awake. The great San Francisco earthquake, and the fire that followed, devastated the city and claimed an estimated 3,000 lives.