On March 27, 1964, at 5:36 PM local time, a magnitude 8.3 earthquake struck southern Alaska. This was the second most powerful earthquake ever recorded with modern seismometers. It resulted from slippage of the Pacific Plate under the North American Plate at a depth of about 30 km in the eastern Aleutian subduction zone. Four minutes of intense ground shaking caused serious damage in Anchorage, 130 km from the epicenter. Of the 129 fatalities, 120 resulted from tsunamis (large ocean waves), which pounded the coast as far south as California. The main shock was followed by 175 aftershocks of magnitude 5 or greater during the following 3 days.
