The Great Alaskan Earthquake 1964
The Largest Earthquake Ever Recorded in North America
Statistics of the Great Alaskan Earthquake of 1964
On Good Friday, March 27, 1964, at 5:36 PM local time in Alaska, an earthquake with a magnitude of 9.2 struck Prince William Sound. This earthquake is the third largest recorded in the world. Within the first 24 hours, there were 11 aftershocks and with a magnitude greater than 6.0 and 9 more took place over the next few weeks. In total, there were over 10,000 aftershocks.
The second strongest earthquake in the world occurred on December 26 2004 and had a magnitude of 9.3. The epicenter was on the ocean floor near the west coast of Sumatra. The strongest earthquake in the world occured in Valdivia Chile on May 22 1960 with a magnitude of 9.5 on the Richter scale.
Cause of the Great Alaskan Earthquake of 1964
Coastal Alaska is on a fault zone where the Pacific plate meets the North American plate. The earthquake took place on a thrust fault where the Pacific plate slips underneath the North American plate. It was determined that the slip of the continental plate took place 16 miles underground. The epicenter was near Prince William Sound which is situated between Valdez and Anchorage.
The ground clay turned to liquid and caused it to become unstable. This is a process called liquefaction. Fissures opened up as more solid ground dropped, rose up and tilted. Some residents claimed the ground waves were over 3 feet high.
Cities and Towns Most Affected by the Great Alaskan Earthquake of 1964
Anchorage suffered the most damage because of liquefaction:
- An area of clay bluffs, called Turnagain Heights collapsed and over 75 homes were lost.
- Part of the main street sunk into a 10 foot hole and extensive damage was done to buildings in a 30 block radius.
- The façade at the J.C.Penney store broke away from the building and crashed into the street, killing two people.
- An apartment building and several schools collapsed.
- The air traffic control tower at the Anchorage airport fell over, killing the controller.
- Water, sewer and gas lines ruptured plus telephone and electrical service were disrupted.
- Nine deaths were reported.
Valdez: is located 120 miles east of Anchorage:
- A freighter at the town dock was being unloaded. The wave created by the earthquake entered the harbor and lifted the freighter 30 feet. There were 28 people killed at the dock and the freighter broke free into the harbor.
- Many waterfront homes and commercial buildings were destroyed.
- Large waves continued at 30 minute cycles for the next 9 hours.
- The waves combined with high tide, caused extensive flooding.
Seward:
- Located 80 miles south of Anchorage, it also experienced huge harbor waves and flooding.
- The biggest catastrophe was the fires that broke out. Tanks at a large oil storage facility exploded and sent flames across the harbor.
- Twelve people died.
Kodiak Island:
- It was not damaged by the earthquake but it was hit by very large harbor waves.
- The water in the harbor suddenly receded and it sunk down to 2 feet, leaving fishing boats sitting on the bottom. This was caused by the pulling of the waves.
- When the waves struck, the boats were tossed into the town, some of them 3 blocks from the harbor.
- Two canneries were wiped out.
- Eight people died.
Tsunami Caused by the Great Alaskan Earthquake of 1964
The uplift of the ocean floor generated a tsunami with an estimated speed of 400 miles per hour. This caused more deaths in areas outside of Alaska. The tsunami went across the Pacific as far as the Hawaiian Islands. Along the North American coast, there were waves that caused extensive property damage.
- The worst hit was Port Alberni British Columbia Canada where the wave funneled through an inlet and it washed away 55 homes and damaged 375 others. Nobody was killed.
- There were 12 people killed in Crescent City California and 4 died in Beverly Beach State Park in Oregon. Other coastal towns and cities (including Hawaii) also suffered damage.
It was fortunate that the death toll was very small considering the size of the earthquake. This was due to the low density of population in Alaska. Because it was Good Friday many businesses and schools were closed. It is also a good thing that many of the buildings in Alaska were built out of wood because it is a more flexible material.
Sources:
- U.S. Geological Survey (includes pictures)
- Vibration Data
Related Articles on Earthquakes:
The 1906 Great San Francisco Earthquake
The 1989 San Francisco Earthquake
New Madrid Earthquake USA, 1911-1912
Haiti Earthquake January 12, 2010
Anchorage Alaska Earthquake Damage
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Tire Impaled by Tsunami in Whittier Alaska
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Landslide Turnagain Heights Anchorage
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Glacier Bay Alaska
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