Good Friday Tsunami (1964)

At 5:36 P.M. on March 27, 1964 (Good Friday), one of the most powerful earthquakes on record struck the Gulf of Alaska. The quake, with an epicenter nearly 500 miles from the nearest coast, lasted for three to four minutes and registered 9.6 on the Richter scale. The quake was felt over an area of 500,000 square miles. Earthquake damage in Anchorage was significant, with parts of the downtown area thrust up nearly 30 feet. The earthquake was associated with the development of several tsunamis that are collectively known as the Good Friday tsunami of 1964.

There are two basic forms of tsunami. The first is caused by tectonic activity, such as a powerful earthquake. The second is caused by a submarine landslide. This can be caused by earthquake activity, but other causes are possible. In 1964, both forms of tsunami were present. Combined, the earthquake and tsunami killed 115 people. Of those, 25 were killed by the consequences of tectonic tsunamis, while 81 were killed by tsunamis created by a submarine slide.

A tsunami, which is a pressure wave moving through the ocean, may be virtually unnoticeable to those in the immediate vicinity if the tsunami is still in deep water. As the pressure wave approaches a coastline, it pushes the water ahead of it, creating a wave. When a tsunami strikes a coastline, it causes the water along the coast to rise. This is referred to as the run-up, and includes not only the tsunami water, but also the water from rivers or bays pushed forward by the force of the tsunami pressure wave. In 1964, the run-up in Shoup Bay, near Valdez, Alaska, was 170 feet.

The effects of a tsunami are largely associated with the proximity of their cause to the affected area. A tsunami created near a coastline can create a worst-case scenario, with a wave of 30 to 45 feet striking in five to 45 minutes. In such circumstances, there would be insufficient time to alert those threatened by the approaching tsunami to evacuate, let alone those in the hazard area. The second type of tsunami is a remote tsunami, creating a wave that travels hundreds of miles that, because of the distance from the causal event, may not be expected by the threatened populace. The 1964 tsunami impacted both immediate and remote areas.

The tsunami struck Alaska approximately 20 to 45 minutes after the quake, depending on distance from the epicenter. The effects were felt in Kodiak 30 minutes after the earthquake, and 45 minutes afterward in Valdez. Several small fishing villages were devastated. Proportional to the population, Chenega, Alaska, suffered the greatest damage from the tsunami. A small village, Chenega had 10 buildings and a population of 75. When the wave struck, it destroyed 80 percent of the buildings, including the community's church, which was being used as a shelter. Twenty-three people, or nearly 31 percent of the population, were killed, including many of the village elders, who had taken refuge in the church.

The remote effects of the tsunami caused $10 million in damage to the Canadian Pacific coast, and $20 million in damage and 16 deaths on the west coast of the United States. Crescent City, California, nearly 1,600 [Page 250]miles from the quake, was struck almost five hours after the earthquake. The tsunami caused 20-foot floodwaters in the downtown area. It killed 12 people, and 29 city blocks were destroyed. The harbor was heavily damaged, with 15 boats destroyed. Four hundred families were displaced.

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