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.
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
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