Today In History: 27 March 1964 – Devastating Earthquake 9.2M in Alaska


On the 27th of March 1964 USCG; At 5:36pm local time (March 28 at 3:36 UTC) an earthquake of magnitude 9.2 occurred in the Prince William Sound region of Alaska, triggering a major tsunami that claimed 139 lives and caused damage from the Kodiak Islands to northern California.

The earthquake rupture started approximately 25 km beneath the surface, with its epicenter about 6 miles (10 km) east of the mouth of College Fiord, 56 miles (90 km) west of Valdez and 75 miles (120 km) east of Anchorage.

The earthquake lasted 4.5 minutes and is still the second largest instrumentally recorded in the world, next to the M9.5 earthquake in Chile in 1960. It remains the most powerful recorded earthquake in US history.

The shock generated a tsunami that devastated many towns along the Gulf of Alaska, and left serious damage at Alberni and Port Alberni, Canada. It even took 15 lives along the West Coast of the United States, and also felt in Hawaii.

Image: US Geological Survey.

The maximum wave height recorded was 67 meters at Valdez Inlet. It was also recorded on tide gages in Cuba and Puerto Rico.

Great Alaska Earthquake
U.S. GEOLOGICAL SURVEY/AP The Government Hill Elementary School is shown destroyed by a landslide following an earthquake in Anchorage, Alaska, March 1964

The earthquake was felt over a large area of Alaska and in parts of western Yukon Territory and British Columbia, Canada.

The earthquake was accompanied by vertical displacement over an area of about 520,000 square kilometers. The major area of uplift trended northeast from southern Kodiak Island to Prince William Sound and trended east-west to the east of the sound. Vertical displacements ranged from about 11.5 meters of uplift to 2.3 meters of subsidence relative to sea level. Off the southwest end of Montague Island, there was absolute vertical displacement of about 13 – 15 meters. Uplift also occurred along the extreme southeast coast of Kodiak Island, Sitkalidak Island, and over part or all of Sitkinak Island. This zone of subsidence covered about 285,000 square kilometers, including the north and west parts of Prince William Sound, the west part of the Chugach Mountains, most of Kenai Peninsula, and almost all the Kodiak Island group.

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