The Good Friday Alaska Earthquake of 3/27/64

The pic. above is Fourth Avenue in Anchorage, Alaska right after the big earthquake of March 27, 1964. Here the pavement sank 11 feet in response to 14 feet of horizontal movement.

The quake occurred at 5:36 pm on Good Friday, sixty years ago. The shaking lasted an incredible 4 minutes and 38 seconds. The temblor measured magnitude 9.2 and it remains the strongest earthquake in modern history in North America and 2nd strongest in modern world history after the 9.5 Chile quake of 1960. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis resulting from the earthquake caused 131 deaths.

Six hundred miles (970 km) of fault ruptured at once and moved up to 60 ft. (18 m), releasing about 500 years of stress buildup. Soil liquefaction, fissures, landslides, and other ground failures caused major structural damage much damage to property. Anchorage sustained great destruction or damage to many inadequately earthquake-engineered houses, buildings, and infrastructure (paved streets, sidewalks, water and sewer mains, electrical systems, and other man-made equipment), particularly in the several landslide zones along Knik Arm. Two hundred miles (320 km) southwest, some areas near Kodiak were permanently raised by 30 feet (9 m). Southeast of Anchorage, areas around the head of Turnagain Arm near Girdwood and Portage dropped as much as 8 feet (2.4 m), requiring reconstruction and fill to raise the Seward Highway above the new high tide mark.

In Prince William Sound, Port Valdez suffered a massive underwater landslide, resulting in the deaths of 32 people between the collapse of the Valdez city harbor and its docks, and inside a ship that was docked there at the time. Nearby, a 27-foot (8.2 m) tsunami destroyed the village of Chenega, killing 23 of the 68 people who lived there. Survivors out-ran the wave, climbing to higher ground.

Post-quake tsunamis severely affected Whittier, Seward, Kodiak, and other Alaskan communities, as well as people and property in British Columbia, Washington, Oregon, and California.^[4] Tsunamis also caused damage in Hawaii and Japan. Tsunami waves were noted in over 20 countries, including Peru, New Zealand, Papua New Guinea, Japan, Mexico, and in the continent of Antarctica. The largest tsunami wave was recorded in Shoup Bay, Alaska, with a height of about 220 ft. (67 m) Evidence of motion directly related to the earthquake was also reported from Florida and Texas.

Twelve people were killed by the tsunami in or near Crescent City, California, while four children were killed on the Oregon coast at Beverly Beach State Park.^[21] Other coastal towns in the U.S. Pacific Northwest and Hawaii were damaged. Minor damage to boats occurred as far south as Los Angeles.^[22] Effects of the earthquake were even noted as far east as Freeport, Texas, where tide gauges recorded waves similar to seismic surface waves.^[23]Seiches were detected in wells in countries around the world, including England, Namibia, and Australia.

A fault between the Pacific and North American plates ruptured near College Fjord in Prince William Sound. The epicenter of the earthquake was 12.4 mi (20 km) north of Prince William Sound, 78 miles (125 km) east of Anchorage and 40 miles (64 km) west of Valdez. The focus occurred at a depth of approximately 15.5 mi (25 km). Ocean floor shifts created large tsunamis (up to 220 feet (67 m) in height), which resulted in many of the deaths and much of the property damage.^[5] Large rockslides were also caused, resulting in great property damage. Vertical displacement of up to 38 feet (11.5 m) occurred, affecting an area of 100,000 square miles (260,000 km²) within Alaska.

There were hundreds of aftershocks in the first weeks following the main shock. In the first day alone, eleven major aftershocks were recorded with a magnitude greater than 6.0. Nine more struck over the next three weeks. In all, thousands of aftershocks occurred in the months following the quake, and smaller aftershocks continued to strike the region for more than a year.

In the longer term, the U.S. Army Corps of Engineers led the effort to rebuild roads, clear debris, and establish new town sites for communities that had been completely destroyed, at a cost of $110 million.^[29] The West Coast and Alaska Tsunami Warning Center was formed as a direct response to the disaster. Federal disaster relief funds paid for reconstruction as well as financially supporting the devastated infrastructure of Alaska’s government, spending hundreds of millions of dollars that helped keep Alaska financially solvent until the discovery of massive oil deposits at Prudhoe Bay.