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Most Powerful North American Earthquake: The Great Alaskan Earthquake

On March 27, 1964, Alaska experienced the most powerful earthquake in North American and the second most powerful earthquake ever recorded in an event that became known as the Great Alaskan Earthquake or Good Friday Earthquake. The only recorded earthquake that had a stronger moment magnitude was the 1960 Valdivia earthquake in Chile, where 2,230-6,000 people died and the cost of damage ranged between US$400-$800 million.

At 5:36 p.m., the fault between the Pacific and North American plates ruptured in the Prince William Sound resulting in an earthquake that had magnitude of 9.2. The Maximum Intensity on the Mercalli scale classified the earthquake as an “extreme” earthquake, which means that “few, if any structures remain standing” and that there are “numerous landslides, cracks and deformations of the ground.” The epicenter of the earthquakes was located 78 miles east of Anchorage and 40 miles west of Valdez at a depth of 15.5 miles. The Great Alaskan Earthquake was a megathrust earthquake because of the location of the Aleutian fault line, which is located at the subduction zone between the Pacific and North American plates. 

The earthquake caused soil liquefaction, which caused rockslides on land, resulting in property damage. The soil liquefaction also resulted in massive underwater landslides, which caused tsunami waves throughout the Pacific Ocean. The Port of Valdez, where the underwater landslide originated, was wrecked and 30 people died as the tsunami waves and landslide destroyed the town’s harbor, docks, and ships. Tsunami waves were measured in 20 countries with the highest waves being measured in Shoup Bay, Alaska at 67 meters in height.

In total, 139 people died in Great Alaskan Earthquake. While the earthquake itself caused only 15 deaths, the tsunami caused 106 deaths in Alaska, 5 deaths in Oregon, and 13 deaths in California. The total cost of damage caused by the earthquake was $311 million. While Anchorage was not affected by tsunami waves, it received the most damage from the earthquake, while other Alaskan towns, such as Chenega and Portage were completely destroyed.

Items in Our Collection:

The Great Alaskan Earthquake of 1964 by National Research Council Committee of the Alaska Earthquake

Tectonics of the March 27, 1964, Alaska Earthquake by George Plafker

The Prince William Sound, Alaska, earthquake of 1964 and aftershocks by Ferus J Wood, Louis E Leipold, US Coast and Geodetic Survey; United States Environmental Science Services Administration; United States Department of Commerce