In the late afternoon of March 27. 1964 Alaska was shattered for three to five minutes by one of the (second) strongest and destructive earthquakes ever to be recorded in modern times, magnitude 9.2.
The earthquake displaced almost the entire south coast of Alaska along Prince William Sound, some areas were raised by 9 meters and along some faults the displacement reached 15 meters. The Earthquake caused heavy damage on 75% of buildings and infrastructure in Alaska, the costs of the disaster was estimated in hundreds of millions dollars, but because of the sparsely inhabited area hit, death toll was low with only 131 people killed.
Ground fissures opened; more than 2.000 landslides and avalanches occurred across south-central Alaska, most remarkable were the generated tsunamis, its effects observed even in Japan. Buildings in Seattle (Washington) begun to swing by the approaching seismic wave, the ground was measurable deformed even in Florida.
On some lakes in Alaska the movement of the water cast chunks of ice onto the land, causing damage on the surrounding trees up to 9 meters above ground. Unusual water movements, attributed cautiously to the earthquake, were observed in the South Dakota and so far as Puerto Rico and Australia.
In Anchorage the earthquake was felt for 10 seconds, then the ground collapsed, up to 400 meter long fissures opened, houses and streets were engulfed by the liquefied underlying argillite.
The earthquake displaced almost the entire south coast of Alaska along Prince William Sound, some areas were raised by 9 meters and along some faults the displacement reached 15 meters. The Earthquake caused heavy damage on 75% of buildings and infrastructure in Alaska, the costs of the disaster was estimated in hundreds of millions dollars, but because of the sparsely inhabited area hit, death toll was low with only 131 people killed.
Ground fissures opened; more than 2.000 landslides and avalanches occurred across south-central Alaska, most remarkable were the generated tsunamis, its effects observed even in Japan. Buildings in Seattle (Washington) begun to swing by the approaching seismic wave, the ground was measurable deformed even in Florida.
On some lakes in Alaska the movement of the water cast chunks of ice onto the land, causing damage on the surrounding trees up to 9 meters above ground. Unusual water movements, attributed cautiously to the earthquake, were observed in the South Dakota and so far as Puerto Rico and Australia.
In Anchorage the earthquake was felt for 10 seconds, then the ground collapsed, up to 400 meter long fissures opened, houses and streets were engulfed by the liquefied underlying argillite.
Fig.1. Aerial photographs of destructive land-slides and damage in Anchorage Graben at head of a landslide. Photo by A. Grantz/ U. S.Geological Survey.Many of these phenomena will be later observed and studied for the very first time by scientists - two hours after the earthquake the first geologists arrived to Anchorage.
A half hour later the tsunami reached the city of Valdez.
The residents of Valdez after the earthquake had hoped to find shelter at the local harbour, but from the sea a 30 meter high wave approached the coast. A 10.000 ton heavy ship was thrown on land, the light-house and many buildings torn away, 32 people were killed by the earthquake and the impact of the wave on land. For hours after the earthquake the sea was tumultuous, in the evening with the high tide slowly the waves again inundated the surviving area of the city of Valdez.
In the seaport of Seward on the peninsula of Kenai the wave knocked over a 110 ton heavy locomotive and destroyed the tubes of an oil refinery, the effluent oil exploded and a terrible fire broke out.
Six hours later the wave reached (the island of) Vancouver Island, an hour later the coast of Oregon, the wave continued its path of destruction until Crescent City in California.
The effects of the tsunami were observed across the Pacific Ocean even in Japan.
Fig.2. Alaska Earthquake March 27, 1964. Rockslide avalanche on Sherman Glacier. The source was from the area marked by the fresh scar on Shattered Peak (middle distance). The debris displays flowlines and terminal digitate lobes. No marginal dust layer is present. The steep margin, about 20 meters above the clear ice, is due to more rapid melting of the exposed glacier than the ice protected by the debris. Photo by A. Post, August 25, 1965/ Geological Survey.
Bibliography:
Committee on the Alaska Earthquake of the Division of Earth Sciences National Research Council (1968): The Great Alaska Earthquake of 1964. National Academy of Sciences, Washington: 473
GATES, A.E. & RITCHIE, D. (2007): Encyclopedia of earthquakes and Volcanoes. Facts on file science library. 3th ed. New York: 346
WALKER, B. (1982): Earthquake. Planet Earth. Time Life Books: 154
Online Resources:
GATES (2007): U.S.G.S. (21.10.2009): Historic Earthquakes - Prince William Sound, Alaska 1964.
The residents of Valdez after the earthquake had hoped to find shelter at the local harbour, but from the sea a 30 meter high wave approached the coast. A 10.000 ton heavy ship was thrown on land, the light-house and many buildings torn away, 32 people were killed by the earthquake and the impact of the wave on land. For hours after the earthquake the sea was tumultuous, in the evening with the high tide slowly the waves again inundated the surviving area of the city of Valdez.
In the seaport of Seward on the peninsula of Kenai the wave knocked over a 110 ton heavy locomotive and destroyed the tubes of an oil refinery, the effluent oil exploded and a terrible fire broke out.
Six hours later the wave reached (the island of) Vancouver Island, an hour later the coast of Oregon, the wave continued its path of destruction until Crescent City in California.
The effects of the tsunami were observed across the Pacific Ocean even in Japan.
Fig.2. Alaska Earthquake March 27, 1964. Rockslide avalanche on Sherman Glacier. The source was from the area marked by the fresh scar on Shattered Peak (middle distance). The debris displays flowlines and terminal digitate lobes. No marginal dust layer is present. The steep margin, about 20 meters above the clear ice, is due to more rapid melting of the exposed glacier than the ice protected by the debris. Photo by A. Post, August 25, 1965/ Geological Survey.Bibliography:
Committee on the Alaska Earthquake of the Division of Earth Sciences National Research Council (1968): The Great Alaska Earthquake of 1964. National Academy of Sciences, Washington: 473
GATES, A.E. & RITCHIE, D. (2007): Encyclopedia of earthquakes and Volcanoes. Facts on file science library. 3th ed. New York: 346
WALKER, B. (1982): Earthquake. Planet Earth. Time Life Books: 154
Online Resources:
GATES (2007): U.S.G.S. (21.10.2009): Historic Earthquakes - Prince William Sound, Alaska 1964.
The tsunami snuck up the fjord of Port Alberni, BC. I think it formed a seiche although I can't find documentation for that at the moment, but it is the case held up as an example of our tsunami vulnerability. The municipal website and CBC archives provide more details.
ReplyDeleteJust a note, the the last paragraph you wrote "the island of Vancouver" which implies that you are referring to the City of Vancouver and the (small) island it lies upon, but I think you are probably meaning to describe Vancouver Island, where a destructive tsunami hit in 1964, while the City of Vancouver is sheltered from the Pacific Ocean and was unscathed during this event. If I am mistaken, ignore me, but as a native to Vancouver Island, I was slightly confused as to which you were meaning to describe.
ReplyDeleteThanks for the information – in fact it is Vancouver Island!
ReplyDeleteI found the notion that there were a first wave, channelized by the fjord and so higher than expected by the earthquake and water depth, following immediately the earthquake and this would be a tsunami in strict sense, (reflected?) waves combined with the beginning high tide followed hours later (GATES & RITCHIE 2007) – this is very interesting as the documentary refers to tidal waves after midnight.