http://humboldt.edu- 10/14/13
Most earthquakes occur at or near plate boundaries. The motion of these plates stress faults through Northern California.
In the past 150 years, nearly 40 earthquakes of magnitude 6 or larger have affected Northern California. Most of these earthquakes were centered on faults nearby. But very large earthquakes located elsewhere in the Pacific basin, like the 1964 magnitude 9.2 Alaska earthquake can generate tsunamis that threaten our coast.
