Fifty years ago, a 9.2-magnitude earthquake rocked Alaska for nearly five minutes. Once the shaking from the largest earthquake ever recorded in North America stopped, however, the worst was yet to come.
[slideshow]As the sunlight waned on March 27, 1964, Alaska’s frozen ground shivered violently. Periodic rumbles were nothing new to Alaskans—four out of every five U.S. earthquakes occur in the state—but the quake that struck at 5:36 p.m. local time on Good Friday was unlike any they had experienced before.
The earthquake centered 75 miles east of Anchorage caused the ground of south central Alaska to heave and convulse. Alaskans struggled to stay on their feet. Roads cracked like shattered peanut brittle. Telephone poles snapped like matchsticks. Trees whipped so viciously that their tops touched the ground. Groaning buildings buckled. The severe shaking pulverized the soil into a quicksand that swallowed houses and cars.[slideshow]
The Great Alaska Earthquake lasted for nearly five minutes and registered a magnitude of 9.2, still the largest ever recorded in North America and second only to the 9.5-magnitude quake that struck Chile in 1960. According to the U.S. Geological Survey (USGS), the earthquake was as powerful as all subsequent American earthquakes combined and “so large that it caused the entire Earth to ring like a bell.” More than 1,000 miles away in Seattle, the Space Needle swayed from the vibration, and water-level recorders in every state except for Rhode Island, Delaware and Connecticut registered the quake. Water sloshed in harbors as far away as Louisiana, where several fishing boats capsized as a result. Life magazine reported at the time that the earthquake contained 400 times the total energy of all nuclear bombs ever exploded up to 1964.
The shaking left behind destruction of truly seismic proportions. Along Anchorage’s Fourth Avenue, which dropped 20 feet, basements became first floors. Buildings collapsed. Gas tanks exploded. Rail lines were bent like licorice sticks and twisted into knots. Utility lines were severed. The powerful earthquake even permanently altered the Alaskan landscape. Geodetic surveys found that much of the state’s southern coastline moved seaward by more than 50 feet. Some areas rose in elevation by nearly 40 feet as others sank by almost 10 feet.
As destructive as the initial shaking was, however, the bigger disaster followed minutes later. The earthquake that began a dozen miles deep under Prince William Sound sparked submarine landslides that triggered catastrophic tsunamis. A monster wave more than 200 feet tall knifed through the Valdez Inlet before slamming into the Alaskan coastline. Tidal waves killed 31 in Valdez along with 25 in Chenega, one-third of the small village’s population. In Seward, the earthquake had ruptured oil tanks that were set ablaze, and when the tsunami arrived, it created a terrifying wave of fire. (Following the earthquake, towns such as Seward, Valdez and Chenega were moved to safer ground.)
Fatalities were not limited to Alaska, however. Tsunamis radiated out from the epicenter, and four hours after the initial earthquake, the sea invaded waterfronts along the Pacific Ocean coastline. With little warning under the cover of darkness around midnight, waves more than 14 feet above tidal height flooded 29 blocks of Crescent City, California, and killed 11. Further north, four campers on a beach in Newport, Oregon, also perished from the waves. The tsunamis even caused damage as far away as Hawaii and Japan.
For more than a year following the devastating earthquake, thousands of aftershocks rattled the frayed nerves of Alaskans. In the first day alone, 11 aftershocks with magnitudes of greater than 6.0 shook the state. According to the USGS, the Great Alaska Earthquake caused over $300 million in damage ($2.3 billion in 2013 dollars) and took the lives of 131 people, 119 of those due to the tsunamis. The sparseness of the Alaskan population kept both numbers low in spite of the earthquake’s power.
Out of the death and destruction, however, the Great Alaska Earthquake left a lasting legacy. Geologists who studied the quake gathered reams of data that provided a greater scientific understanding of earthquakes. Scientists learned more about soil liquefaction and tidal waves, which spurred the development of the National Tsunami Warning Center. In addition, in 1964, plate tectonics was a just-emerging geological theory that the earth’s shell was composed of interlocking plates resembling a jigsaw puzzle, a concept bolstered when it was found that the cause of the Alaskan quake was not a vertical break in a fault, but an angled lunge forward. Geologists have now determined that the Pacific Plate pushes against the North American continent at the rate of 2.3 inches per year, and when the irresistible force finally overwhelmed the immovable object on Good Friday in 1964, it slid underneath the continental plate and violently unleashed centuries of pent-up energy in the Great Alaska Earthquake.