Good Friday Earthquake
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The Good Friday Earthquake (also called the Great Alaska Earthquake) of Friday, March 27, 1964 (Good Friday, a Christian holy day associated with a historical earthquake[1]), 5:36 P.M. AST (03:36 3/27 UTC) had a moment magnitude of 9.2 and was an 8.4 on the Richter scale. It was the most powerful recorded earthquake in U.S. and North American history, and the third most powerful ever measured by seismograph. 131 deaths were attributed to the earthquake. The epicenter of the earthquake was , 20 km north of Prince William Sound, 125 km (78 miles) east of Anchorage and 64 km (40 miles) west of Valdez. The rupture occurred at a depth of approximately 25km and its duration was approximately 4 minutes. The powerful earthquake also caused some parts of Alaska to experience earthquake liquefaction, causing much damage to property and leading to landslides.
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[edit] The earthquake
At 5:36 p.m. Alaska Standard Time (3:36 a.m. March 27, 1964 UTC), just as people were traveling home, a fault between the Pacific and North American plates ruptured near College Fjord in Prince William Sound. The earthquake lasted for three to five minutes in most areas. Ocean floor shifts created large tsunamis (up to 20 meters (70ft) in height), which resulted in many of the deaths and much of the property damage. Large rockslides were also created which resulted in great property damage. Vertical displacement of up to 11.5 m (38 feet) occurred, affecting an area of 250,000 km² (100,000 miles²) within Alaska.
[edit] Type of earthquake
The Good Friday Earthquake was a megathrust (subduction zone) earthquake, caused by the Pacific Plate subducting beneath the North American Plate.
[edit] Death toll, damage and casualties
131 people were killed as a result of the earthquake: 9 in the earthquake itself, 106 from tsunamis in Alaska, and 16 from tsunamis in Oregon and California. Property damage was estimated at over $300 million ($1.8 billion in 2007 U.S. dollars).
[edit] Anchorage area
Most property damage occurred in Anchorage, 120 km (75 mi) northwest of the epicenter. Nine people were killed, the only deaths directly attributed to the earthquake. Anchorage was not hit by tsunamis, but downtown Anchorage was heavily damaged, and parts of the city built on clay or near bluffs, most notably the Turnagain Heights neighborhood, suffered landslide damage. Most other areas of the city were only moderately damaged
The small coastal towns of Girdwood and Portage, located approximately 60 km (40 mi) southeast of Anchorage on Turnagain Arm, were destroyed. Girdwood was later relocated a few miles inland, while Portage, which subsided below the high-water level, was abandoned entirely.
[edit] Elsewhere in Alaska
Most towns in the Prince William Sound, Kenai Peninsula, and Kodiak Island areas, especially the major ports, such as Seward and Kodiak, were heavily hit by a combination of seismic damage, tsunamis, subsidence, and/or fire. Valdez was not totally destroyed as is commonly thought and was inhabited for the next three years; the town was later moved to more solid ground 7 km (4 mi) west of its original site. Several of the smaller, low-lying Alaska Native villages in the area (such as Chenega and Afognak) were mostly or totally destroyed. The earthquake also caused the ballistic missile detection radar of Clear Air Force Station to go offline for six minutes, the only unscheduled interruption in its operational history. The Million Dollar Bridge also collapsed.
[edit] Canada
A 1.4 m (4.5 ft) wave reached Prince Rupert, British Columbia, just south of the Alaska Panhandle, about 3.3 hours after the quake. The tsunami then reached Tofino, on the exposed west coast of Vancouver Island, and travelled up a fjord to hit Port Alberni twice, damaging 375 homes and washing away 55 others. The towns of Hot Springs Cove, Zeballos, and Amai also saw damage. The damage in British Columbia was estimated at $10 million Canadian ($65 million in 2006 Canadian dollars, or $56 million in 2006 U.S. dollars).
[edit] Elsewhere
12 people were killed by the tsunami in Crescent City, California, while four children were killed on the Oregon Coast at Beverly Beach State Park.[2] Other towns along the U.S. Pacific Northwest and Hawaii were damaged. Minor damage to boats reached as far south as Los Angeles.
Since the entire Earth vibrated as a result of the quake, minor effects were felt worldwide: several fishing boats were sunk in Louisiana and water sloshed in wells in South Africa.[3]
[edit] Aftershocks
Over 10,000 aftershocks were recorded following the main shock. In the first day alone, eleven aftershocks were recorded with a magnitude greater than 6.0. An additional nine more occurred over the next three weeks. It was not until eighteen months later that the aftershocks were no longer a danger.
[edit] Gallery
 Dramatic sea level change in Valdez after the earthquake |
 Tire impaled with a piece of wood, due to the force of the tsunami |
 Seward waterfront, mid-1964 |
 Turnagain Heights landslide - exposed earth appears dark against the snow |
[edit] See also
[edit] Notes
- ^ Good Friday is associated with the crucifixion of Jesus, followed by an earthquake according to Matthew 27:51-54)
- ^ Oregon’s pioneer spirit. Statesman Journal, December 26, 1999.
- ^ http://www.usgs.gov/newsroom/article.asp?ID=106
[edit] External links
- USGS report on the earthquake
- U.S. Geological Survey Photo Library -- earthquake photos
- The Great Alaskan Earthquake & Tsunamis of 1964 -- NOAA report
- The Effects of the March 28, 1964 Alaska Tsunami in British Columbia, Canada
- Eyewitness Accounts
