Alaska Earthquake Information Center Roger Hansen Alaska spans 4,800 km of the boundary between the oceanic Pacific and continental North American plates and is one of the world's most active regions associated with earthquakes and volcanism.
Earthquakes occur throughout most areas of the entire state.
The greatest concentration of earthquakes is along the Pacific margin where the Pacific plate is being subducted beneath southern Alaska and the Aleutian Islands. The historical record indicates that magnitude 7 and larger shocks are about seven times more frequent in southern Alaska than in California. Three of the seven largest earthquakes in the world this century originated in Alaska on the boundary between the Pacific and North American plates. The northwestward motion of the Pacific plate relative to the North American plate is accommodated by dextral transcurrent faulting in southeast Alaska on the Queen Charlotte-Fairweather fault system, and by underthrusting and subduction of the Pacific plate along the Aleutian megathrust. Prior to the Good Friday earthquake of 1964, there were only two seismographic stations in Alaska that operated with any degree of regularity.