O Grande Sismo do Alasca foi há 58 anos

Fourth Avenue in Anchorage, Alaska, looking east from near Barrow Street. The southern edge of one of several landslides in Anchorage, this one covered an area of over a dozen blocks, including 5 blocks along the north side of Fourth Avenue. Most of the area was razed and made an urban renewal district

       
The 1964 Alaskan earthquake, also known as the Great Alaskan Earthquake, the Portage Earthquake and the Good Friday Earthquake, was a megathrust earthquake that began at 5:36 P.M. AST on Good Friday, March 27, 1964. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis resulting from the earthquake caused about 143 deaths.

Lasting nearly three minutes, it was the most powerful recorded earthquake in U.S. and North American history, and the second most powerful ever measured by seismograph. It had a magnitude of 9.2, making it the second largest earthquake in recorded history.

The powerful earthquake produced earthquake liquefaction in the region. Ground fissures and failures caused major structural damage in several communities, much damage to property and several landslides. Anchorage sustained great destruction or damage to many inadequately 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 southwest, some areas near Kodiak were permanently raised by 30 feet (9.1 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 30 people between the collapse of the Valdez city harbor and docks, and inside the 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 high ground. Post-quake tsunamis severely affected Whittier, Seward, Kodiak, and other Alaskan communities, as well as people and property in British Columbia, Oregon, and California. Tsunamis also caused damage in Hawaii and Japan. Evidence of motion directly related to the earthquake was reported from all over the earth.

  

      

Geology

At 5:36 p.m. Alaska Standard Time (3:36 a.m. March 28, 1964 UTC), a fault between the Pacific and North American plates ruptured near College Fjord in Prince William Sound. The epicenter of the earthquake was 61.05°N 147.48°W, 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. 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 miles² (250,000 km²) within Alaska.

Studies of ground motion have led to a peak ground acceleration estimate of 0.14 - 0.18 g.

The Alaska Earthquake was a subduction zone earthquake (megathrust earthquake), caused by an oceanic plate sinking under a continental plate. The fault responsible was the Aleutian Megathrust, a reverse fault caused by a compressional force. This caused much of the uneven ground which is the result of ground shifted to the opposite elevation.
  

 

Calculated travel time map for the tectonic tsunami produced by the 1964 Prince William Sound earthquake in Alaska

          
Death toll, damage and casualties

Various sources indicate that about 131 people died as a result of the earthquake: nine as a result of earthquake itself, 106 from subsequent tsunamis in Alaska and 16 from tsunamis in Oregon and California. Property damage was estimated at over $310 million ($2.25 billion in current U.S. dollars).

   

Anchorage area

Most damage occurred in Anchorage, 75 mi (120 km) northwest of the epicenter. Anchorage was not hit by tsunamis, but downtown Anchorage was heavily damaged, and parts of the city built on sandy bluffs overlying "Bootlegger Cove clay" near Cook Inlet, most notably the Turnagain neighborhood, suffered landslide damage. The neighborhood lost 75 houses in the landslide, and the destroyed area has since been turned into Earthquake Park. The Government Hill school suffered from the Government Hill landslide leaving it in two jagged, broken pieces. Land overlooking the Ship Creek valley near the Alaska Railroad yards also slid, destroying many acres of buildings and city blocks in downtown Anchorage. Most other areas of the city were only moderately damaged. The 60-foot concrete control tower at Anchorage International Airport was not engineered to withstand earthquake activity and collapsed, killing one employee.

The house at 918 W. 10th Avenue suffered damage peripherally, but one block away the recently completed and still unoccupied Four Seasons Building on Ninth Avenue collapsed completely with one whole wing sticking up out of the rubble like a seesaw.

The hamlets of Girdwood and Portage, located 30 and 40 mi (60 km) southeast of central Anchorage on the Turnagain Arm, were destroyed by subsidence and subsequent tidal action. Girdwood was relocated inland and Portage was abandoned. About 20 miles (32 km) of the Seward Highway sank below the high-water mark of Turnagain Arm; the highway and its bridges were raised and rebuilt in 1964-66.
     

A winter scene of a "Ghost forest" that was killed and preserved by salt water along with ruined buildings at the site of the former town of Portage, 2011

        
Elsewhere in Alaska

Most coastal towns in the Prince William Sound, Kenai Peninsula, and Kodiak Island areas, especially the major ports of Seward, Whittier and Kodiak were heavily damaged by a combination of seismic activity, subsidence, post-quake tsunamis and/or earthquake-caused fires. Valdez was not totally destroyed, but after three years, the town relocated to higher ground 7 km (4 mi) west of its original site. Some Alaska native villages, including Chenega and Afognak, were destroyed or damaged. The earthquake caused the Cold-War era ballistic missile detection radar of Clear Air Force Station to go offline for six minutes, the only unscheduled interruption in its operational history. Near Cordova, the Million Dollar Bridge crossing the Copper River also collapsed. The community of Girdwood was also confined to the southern side of the Seward Highway when water rushed into Turnagain Arm arm and flooded or destroyed any buildings left standing to the north of the highway. Interestingly, only the ground immediately along the highway and that on the north side of the road dropped, prompting geologists to speculate that Girdwood may rest upon an ancient cliff face, now covered by countless thousands of years of sediment and glacial deposits.

   

Canada
A 4.5 ft (1.4 m) wave reached Prince Rupert, British Columbia, just south of the Alaska Panhandle, about three hours after the quake. The tsunami then reached Tofino, on the exposed west coast of Vancouver Island, and traveled up a fjord to hit Port Alberni twice, washing away 55 homes and damaging 375 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).
    
Elsewhere
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. Other towns along the U.S. Pacific Northwest and Hawaii were damaged. Minor damage to boats reached as far south as Los Angeles.
As the entire planet 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 Africa.
    
Aftershocks
There were thousands of aftershocks for three weeks, following the main shock. In the first day alone, eleven major aftershocks were recorded with a magnitude greater than 6.2. Nine more occurred over the next three weeks. It was not until more than a year later that the aftershocks were no longer noticed.

       

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O Exxon Valdez provocou uma enorme maré negra no Alasca há 33 anos

 

    

Exxon Valdez (atualmente chamado Dong Fang Ocean e anteriormente conhecido também como Exxon Mediterranean, SeaRiver Mediterranean, S/R Mediterranean e Mediterranean) foi um navio petroleiro que ganhou notoriedade a 24 de março de 1989, quando entre 50.000 m³ e 150.000 m³ (aproximadamente 257.000 barris) do petróleo que transportava foram lançadas ao mar, na costa do Alasca, depois de o navio encalhar na Enseada do Príncipe Guilherme (Prince William Sound). Como consequência, houve um grande desastre ambiental. Centenas de milhares de animais morreram nos meses seguintes. De acordo com as estimativas, morreram 250.000 pássaros marinhos, 2.800 lontras marinhas, 250 águias e 22 orcas, além da perda de milhares de milhões de ovos de salmão. Foi o segundo maior derrame de petróleo da história dos Estados Unidos. Na época, o navio pertencia à ExxonMobil.

  

  

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Os Estados Unidos tomaram posse do seu maior estado há 154 anos

O Alasca, à esquerda, em vermelho, com a sua localização na América do Norte

Em 1867, os Estados Unidos da América compraram o território do Alasca ao Império Russo. A operação foi conduzida pelo Secretário de Estado norte-americano William Henry Seward.

À época, a transação foi considerada absurda e era referida como "a loucura de Seward" (William H. Seward's folly). O território comprado, com área aproximada de 1.600.000 km² constitui o atual estado norte-americano do Alasca.

O Império Russo estava em dificuldades financeiras e em vias de perder o território do Alasca sem compensação, em algum futuro conflito, sobretudo para o rival da época, o Império Britânico, que detinha o vizinho Canadá e cuja possante Royal Navy poderia facilmente tomar o controle da costa, de defesa difícil para a Rússia. O Czar Alexandre II decidiu então vender o território aos Estados Unidos e encarregou o seu embaixador, o barão Edouard de Stoeckl, de abrir negociações com o Secretário de Estado William Seward, de quem era amigo, no início de março de 1867.
As negociações concluíram-se após discussões que duraram uma noite inteira e a assinatura do tratado foi feita às 4 horas da manhã de 30 de março com um preço de compra de 7.200.000 dólares americanos. A opinião pública americana foi muitíssimo desfavorável a esta compra.
O Senado dos Estados Unidos da América ratificou o tratado a 9 de abril de 1867, por 37 votos a favor e 2 contra.
Estima-se que o Alasca contava na altura com 2.500 russos ou mestiços e 8.000 aborígenes, no total mais de 10 000 habitantes, sob o comando direto da companhia russa das peles, e cerca de 50.000 esquimós viviam sob essa jurisdição.
Os europeus viviam em 23 povoações sitas nas ilhas ou na costa. Em pequenos postos, havia quatro ou cinco russos que se encarregavam da compra e armazenamento de peles trazidas pelos nativos e do reabastecimento de navios que vinham buscar a mercadoria. Havia duas vilas principais. A primeira, New Archangel, atualmente Sitka, foi fundada em 1804, como base de apoio ao rentável negócio de peles de leão marinho. Tinha cerca de 116 barracões que abrigavam 968 habitantes. A segunda era Saint-Paul, na ilha Kodiak, que, com 100 barracões e 283 habitantes, era o centro da indústria de peles de foca.
O nome aleúte Alasca foi escolhido pelos americanos. A cerimónia de transferência teve lugar em Sitka, em 18 de outubro de 1867. Soldados russos e americanos desfilaram junto à casa do governador; a bandeira russa foi arriada e a americana hasteada e saudada por salvas de artilharia. O capitão Alexis Pestchouroff disse "General Rousseau, pela autoridade de sua Majestade, o Imperador da Rússia, transfiro aos Estados Unidos da América o território do Alasca". Em retribuição, o general Lovell Rousseau aceitou o território. Numerosos fortes e fortins, construções de madeira, foram cedidos aos americanos. As tropas ocuparam as casernas e o general Jefferson C. Davis estabeleceu a sua residência na casa do governador. A maior parte dos russos voltou ao seu país, salvo alguns comerciantes e homens do clero ortodoxo.
O Alaska Day celebra a transferência formal do Alasca, que ocorreu a 18 de outubro de 1867. Hoje em dia, o Alasca celebra o dia da compra, o Seward's Day, na última segunda de março.
A data de 18 de outubro de 1867 é do calendário gregoriano, e a hora, 9:01:20, hora de Greenwich, teve efeito no dia seguinte no Alasca para substituir o calendário juliano e a hora de 14:58:40 "de avanço" sobre a hora de Greenwich. Para os russos, a transferência teve lugar a 7 de outubro de 1867.

Cheque utilizado pelo governo dos Estados Unidos para a compra do Alasca

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O Alasca foi vendido há 154 anos

   

Em 1867, os Estados Unidos da América compraram à Rússia o território do Alasca. A operação foi conduzida pelo Secretário de Estado americano William Henry Seward.

À época, a transação foi considerada absurda e era referida como "a loucura de Seward" (William H. Seward's folly). O território comprado, com área aproximada de 1.600.000 km², constitui o actual estado americano do Alasca.

   

Situação prévia

O Império Russo estava em dificuldades financeiras e em vias de perder o território do Alasca sem compensação nalgum futuro conflito, sobretudo para o rival da época, o Império Britânico, que detinha o vizinho Canadá e cuja possante Royal Navy poderia facilmente tomar o controlo das costas, de difícil defesa para a Rússia. O Czar Alexandre II decidiu então vender o território aos Estados Unidos e encarregou o seu embaixador, o barão Edouard de Stoeckl, de abrir negociações com o Secretário de Estado William Seward, de quem era amigo, no início de março de 1867.

As negociações concluíram-se após discussões que duraram uma noite inteira e a assinatura do tratado foi feita às 04.00 horas da manhã de 30 de março com um preço de compra de 7.200.000 dólares americanos (equivalente a cerca de 1.670 milhões de dólares, a preços de 2006). A opinião pública americana foi muitíssimo desfavorável a esta compra, como indica um historiador, e as críticas foram numerosas [Oberholtzer, p: 541]:

"Already, so it was said, we were burdened with territory which we had no population to fill. The Indians within the present boundaries of the republic strained our power to govern aboriginal peoples. Could it be that we would now, with open eyes, seek to add to our difficulties by increasing the number of such peoples under our national care? The purchase price was large; the annual charges for administration, civil and military, would be yet greater, and continuing. The territory included in the proposed cession was not contiguous to the national domain. It lay away at an inconvenient and a dangerous distance. The treaty had been secretly prepared, and signed and foisted upon the country at four o'clock in the morning. It was a dark deed done in the night.... The New York World said that it was a "sucked orange." It contained nothing of value but furbearing animals, and these had been hunted until they were nearly extinct. Except for the Aleutian Islands and a narrow strip of land extending along the southern coast the country would be not worth taking as a gift.... Unless gold were found in the country much time would elapse before it would be blessed with Hoe printing presses, Methodist chapels and a metropolitan police. It was "a frozen wilderness".

 

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O Grande Sismo do Alasca foi há 57 anos

Fourth Avenue in Anchorage, Alaska, looking east from near Barrow Street. The southern edge of one of several landslides in Anchorage, this one covered an area of over a dozen blocks, including 5 blocks along the north side of Fourth Avenue. Most of the area was razed and made an urban renewal district

       
The 1964 Alaskan earthquake, also known as the Great Alaskan Earthquake, the Portage Earthquake and the Good Friday Earthquake, was a megathrust earthquake that began at 5:36 P.M. AST on Good Friday, March 27, 1964. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis resulting from the earthquake caused about 143 deaths.

Lasting nearly three minutes, it was the most powerful recorded earthquake in U.S. and North American history, and the second most powerful ever measured by seismograph. It had a magnitude of 9.2, making it the second largest earthquake in recorded history.

The powerful earthquake produced earthquake liquefaction in the region. Ground fissures and failures caused major structural damage in several communities, much damage to property and several landslides. Anchorage sustained great destruction or damage to many inadequately 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 southwest, some areas near Kodiak were permanently raised by 30 feet (9.1 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 30 people between the collapse of the Valdez city harbor and docks, and inside the 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 high ground. Post-quake tsunamis severely affected Whittier, Seward, Kodiak, and other Alaskan communities, as well as people and property in British Columbia, Oregon, and California. Tsunamis also caused damage in Hawaii and Japan. Evidence of motion directly related to the earthquake was reported from all over the earth.

  

    

Geology

At 5:36 p.m. Alaska Standard Time (3:36 a.m. March 28, 1964 UTC), a fault between the Pacific and North American plates ruptured near College Fjord in Prince William Sound. The epicenter of the earthquake was 61.05°N 147.48°W, 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. 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 miles² (250,000 km²) within Alaska.

Studies of ground motion have led to a peak ground acceleration estimate of 0.14 - 0.18 g.

The Alaska Earthquake was a subduction zone earthquake (megathrust earthquake), caused by an oceanic plate sinking under a continental plate. The fault responsible was the Aleutian Megathrust, a reverse fault caused by a compressional force. This caused much of the uneven ground which is the result of ground shifted to the opposite elevation.
  

 

Calculated travel time map for the tectonic tsunami produced by the 1964 Prince William Sound earthquake in Alaska

       
Death toll, damage and casualties

Various sources indicate that about 131 people died as a result of the earthquake: nine as a result of earthquake itself, 106 from subsequent tsunamis in Alaska and 16 from tsunamis in Oregon and California. Property damage was estimated at over $310 million ($2.25 billion in current U.S. dollars).

   

Anchorage area

Most damage occurred in Anchorage, 75 mi (120 km) northwest of the epicenter. Anchorage was not hit by tsunamis, but downtown Anchorage was heavily damaged, and parts of the city built on sandy bluffs overlying "Bootlegger Cove clay" near Cook Inlet, most notably the Turnagain neighborhood, suffered landslide damage. The neighborhood lost 75 houses in the landslide, and the destroyed area has since been turned into Earthquake Park. The Government Hill school suffered from the Government Hill landslide leaving it in two jagged, broken pieces. Land overlooking the Ship Creek valley near the Alaska Railroad yards also slid, destroying many acres of buildings and city blocks in downtown Anchorage. Most other areas of the city were only moderately damaged. The 60-foot concrete control tower at Anchorage International Airport was not engineered to withstand earthquake activity and collapsed, killing one employee.

The house at 918 W. 10th Avenue suffered damage peripherally, but one block away the recently completed and still unoccupied Four Seasons Building on Ninth Avenue collapsed completely with one whole wing sticking up out of the rubble like a seesaw.

The hamlets of Girdwood and Portage, located 30 and 40 mi (60 km) southeast of central Anchorage on the Turnagain Arm, were destroyed by subsidence and subsequent tidal action. Girdwood was relocated inland and Portage was abandoned. About 20 miles (32 km) of the Seward Highway sank below the high-water mark of Turnagain Arm; the highway and its bridges were raised and rebuilt in 1964-66.
     

A winter scene of a "Ghost forest" that was killed and preserved by salt water along with ruined buildings at the site of the former town of Portage, 2011

      
Elsewhere in Alaska

Most coastal towns in the Prince William Sound, Kenai Peninsula, and Kodiak Island areas, especially the major ports of Seward, Whittier and Kodiak were heavily damaged by a combination of seismic activity, subsidence, post-quake tsunamis and/or earthquake-caused fires. Valdez was not totally destroyed, but after three years, the town relocated to higher ground 7 km (4 mi) west of its original site. Some Alaska native villages, including Chenega and Afognak, were destroyed or damaged. The earthquake caused the Cold-War era ballistic missile detection radar of Clear Air Force Station to go offline for six minutes, the only unscheduled interruption in its operational history. Near Cordova, the Million Dollar Bridge crossing the Copper River also collapsed. The community of Girdwood was also confined to the southern side of the Seward Highway when water rushed into Turnagain Arm arm and flooded or destroyed any buildings left standing to the north of the highway. Interestingly, only the ground immediately along the highway and that on the north side of the road dropped, prompting geologists to speculate that Girdwood may rest upon an ancient cliff face, now covered by countless thousands of years of sediment and glacial deposits.

   

Canada
A 4.5 ft (1.4 m) wave reached Prince Rupert, British Columbia, just south of the Alaska Panhandle, about three hours after the quake. The tsunami then reached Tofino, on the exposed west coast of Vancouver Island, and traveled up a fjord to hit Port Alberni twice, washing away 55 homes and damaging 375 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).
    
Elsewhere
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. Other towns along the U.S. Pacific Northwest and Hawaii were damaged. Minor damage to boats reached as far south as Los Angeles.
As the entire planet 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 Africa.
    
Aftershocks
There were thousands of aftershocks for three weeks, following the main shock. In the first day alone, eleven major aftershocks were recorded with a magnitude greater than 6.2. Nine more occurred over the next three weeks. It was not until more than a year later that the aftershocks were no longer noticed.

     

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A maré negra do Exxon Valdez provocou um enorme desastre ambiental há 32 anos

    

Exxon Valdez (atualmente chamado Dong Fang Ocean e anteriormente conhecido também como Exxon Mediterranean, SeaRiver Mediterranean, S/R Mediterranean e Mediterranean) foi um navio petroleiro que ganhou notoriedade a 24 de março de 1989, quando entre 50.000 m³ e 150.000 m³ (aproximadamente 257.000 barris) do petróleo que transportava foram lançadas ao mar, na costa do Alasca, depois de o navio encalhar na Enseada do Príncipe Guilherme (Prince William Sound). Como consequência, houve um grande desastre ambiental. Centenas de milhares de animais morreram nos meses seguintes. De acordo com as estimativas, morreram 250.000 pássaros marinhos, 2.800 lontras marinhas, 250 águias e 22 orcas, além da perda de milhares de milhões de ovos de salmão. Foi o segundo maior derrame de petróleo da história dos Estados Unidos. Na época, o navio pertencia à ExxonMobil.

  

  

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O Exxon Valdez provocou um enorme desastre ambiental há 31 anos

   

Exxon Valdez (atualmente chamado Dong Fang Ocean e anteriormente conhecido também como Exxon Mediterranean, SeaRiver Mediterranean, S/R Mediterranean e Mediterranean) foi um navio petroleiro que ganhou notoriedade a 24 de março de 1989, quando 50.000 m³ a 150.000 m³ (aproximadamente 257.000 barris) do petróleo que transportava foram lançadas ao mar, na costa do Alasca, depois de o navio encalhar na Enseada do Príncipe Guilherme (Prince William Sound). Como consequência, houve um grande desastre ambiental. Centenas de milhares de animais morreram nos meses seguintes. De acordo com as estimativas, morreram 250.000 pássaros marinhos, 2.800 lontras marinhas, 250 águias e 22 orcas, além da perda de milhares de milhões de ovos de salmão. Foi o segundo maior derrame de petróleo da história dos Estados Unidos. Na época, o navio pertencia à ExxonMobil.

  

  

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O Grande Sismo do Alasca foi há 55 anos

Fourth Avenue in Anchorage, Alaska, looking east from near Barrow Street. The southern edge of one of several landslides in Anchorage, this one covered an area of over a dozen blocks, including 5 blocks along the north side of Fourth Avenue. Most of the area was razed and made an urban renewal district

    
The 1964 Alaskan earthquake, also known as the Great Alaskan Earthquake, the Portage Earthquake and the Good Friday Earthquake, was a megathrust earthquake that began at 5:36 P.M. AST on Good Friday, March 27, 1964. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis resulting from the earthquake caused about 143 deaths.

Lasting nearly three minutes, it was the most powerful recorded earthquake in U.S. and North American history, and the second most powerful ever measured by seismograph. It had a magnitude of 9.2, making it the second largest earthquake in recorded history.

The powerful earthquake produced earthquake liquefaction in the region. Ground fissures and failures caused major structural damage in several communities, much damage to property and several landslides. Anchorage sustained great destruction or damage to many inadequately 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 southwest, some areas near Kodiak were permanently raised by 30 feet (9.1 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 30 people between the collapse of the Valdez city harbor and docks, and inside the 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 high ground. Post-quake tsunamis severely affected Whittier, Seward, Kodiak, and other Alaskan communities, as well as people and property in British Columbia, Oregon, and California. Tsunamis also caused damage in Hawaii and Japan. Evidence of motion directly related to the earthquake was reported from all over the earth.

  

Geology

At 5:36 p.m. Alaska Standard Time (3:36 a.m. March 28, 1964 UTC), a fault between the Pacific and North American plates ruptured near College Fjord in Prince William Sound. The epicenter of the earthquake was 61.05°N 147.48°W, 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. 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 miles² (250,000 km²) within Alaska.

Studies of ground motion have led to a peak ground acceleration estimate of 0.14 - 0.18 g.

The Alaska Earthquake was a subduction zone earthquake (megathrust earthquake), caused by an oceanic plate sinking under a continental plate. The fault responsible was the Aleutian Megathrust, a reverse fault caused by a compressional force. This caused much of the uneven ground which is the result of ground shifted to the opposite elevation.

Calculated travel time map for the tectonic tsunami produced by the 1964 Prince William Sound earthquake in Alaska

   
Death toll, damage and casualties

Various sources indicate that about 131 people died as a result of the earthquake: nine as a result of earthquake itself, 106 from subsequent tsunamis in Alaska and 16 from tsunamis in Oregon and California. Property damage was estimated at over $310 million ($2.25 billion in current U.S. dollars).

  

Anchorage area

Most damage occurred in Anchorage, 75 mi (120 km) northwest of the epicenter. Anchorage was not hit by tsunamis, but downtown Anchorage was heavily damaged, and parts of the city built on sandy bluffs overlying "Bootlegger Cove clay" near Cook Inlet, most notably the Turnagain neighborhood, suffered landslide damage. The neighborhood lost 75 houses in the landslide, and the destroyed area has since been turned into Earthquake Park. The Government Hill school suffered from the Government Hill landslide leaving it in two jagged, broken pieces. Land overlooking the Ship Creek valley near the Alaska Railroad yards also slid, destroying many acres of buildings and city blocks in downtown Anchorage. Most other areas of the city were only moderately damaged. The 60-foot concrete control tower at Anchorage International Airport was not engineered to withstand earthquake activity and collapsed, killing one employee.

The house at 918 W. 10th Avenue suffered damage peripherally, but one block away the recently completed and still unoccupied Four Seasons Building on Ninth Avenue collapsed completely with one whole wing sticking up out of the rubble like a seesaw.

The hamlets of Girdwood and Portage, located 30 and 40 mi (60 km) southeast of central Anchorage on the Turnagain Arm, were destroyed by subsidence and subsequent tidal action. Girdwood was relocated inland and Portage was abandoned. About 20 miles (32 km) of the Seward Highway sank below the high-water mark of Turnagain Arm; the highway and its bridges were raised and rebuilt in 1964-66.
  

A winter scene of a "Ghost forest" that was killed and preserved by salt water along with ruined buildings at the site of the former town of Portage, 2011

   
Elsewhere in Alaska

Most coastal towns in the Prince William Sound, Kenai Peninsula, and Kodiak Island areas, especially the major ports of Seward, Whittier and Kodiak were heavily damaged by a combination of seismic activity, subsidence, post-quake tsunamis and/or earthquake-caused fires. Valdez was not totally destroyed, but after three years, the town relocated to higher ground 7 km (4 mi) west of its original site. Some Alaska native villages, including Chenega and Afognak, were destroyed or damaged. The earthquake caused the Cold-War era ballistic missile detection radar of Clear Air Force Station to go offline for six minutes, the only unscheduled interruption in its operational history. Near Cordova, the Million Dollar Bridge crossing the Copper River also collapsed. The community of Girdwood was also confined to the southern side of the Seward Highway when water rushed into Turnagain Arm arm and flooded or destroyed any buildings left standing to the north of the highway. Interestingly, only the ground immediately along the highway and that on the north side of the road dropped, prompting geologists to speculate that Girdwood may rest upon an ancient cliff face, now covered by countless thousands of years of sediment and glacial deposits.

  

Canada
A 4.5 ft (1.4 m) wave reached Prince Rupert, British Columbia, just south of the Alaska Panhandle, about three hours after the quake. The tsunami then reached Tofino, on the exposed west coast of Vancouver Island, and traveled up a fjord to hit Port Alberni twice, washing away 55 homes and damaging 375 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).
  
Elsewhere
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. Other towns along the U.S. Pacific Northwest and Hawaii were damaged. Minor damage to boats reached as far south as Los Angeles.
As the entire planet 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 Africa.
  
Aftershocks
There were thousands of aftershocks for three weeks, following the main shock. In the first day alone, eleven major aftershocks were recorded with a magnitude greater than 6.2. Nine more occurred over the next three weeks. It was not until more than a year later that the aftershocks were no longer noticed.

   

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Um desastre chamado Exxon Valdez ocorreu há trinta anos...

Exxon Valdez (também chamado Dong Fang Ocean e anteriormente conhecido também como Exxon Mediterranean, SeaRiver Mediterranean, S/R Mediterranean e Mediterranean) foi um navio petroleiro que ganhou notoriedade a 24 de março de 1989, quando 50.000 m³ a 150.000 m³ (aproximadamente 257.000 barris) do petróleo que transportava foram lançadas ao mar, na costa do Alasca, depois de o navio encalhar na Enseada do Príncipe Guilherme (Prince William Sound). Como consequência, houve um grande desastre ambiental e centenas de milhares de animais morreram nos meses seguintes. De acordo com as estimativas, morreram 250.000 pássaros marinhos, 2.800 lontras marinhas, 250 águias e 22 orcas, além da perda de milhares de milhões de ovos de salmão. Foi o segundo maior derramamento de petróleo da história dos Estados Unidos. Na época, o navio pertencia à ExxonMobil.

Em 2002, a União Europeia proibiu a utilização de navios petroleiros de casco simples e o “Valdez”, renomeado “Mediterranean”, foi enviado para as águas da Ásia.

Em 2007, o Valdez foi convertido num transportador de minérios e renomeado como “Dong Fang Ocean”.

Em 2011, com o nome de “Oriental Nicety,” o navio foi vendido a uma companhia de demolições indiana, as Priya Blue Industries, a mesma empresa que em 2006 tinha atraído má fama após terem afundado um navio que continha amianto.

Em 2012 o “Oriental Nicety” foi desmantelado na Índia.

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O sismo e tsunami que levaram à criação do Centro de Avisos de Tsunamis do Pacífico foi há 72 anos

A baixa de Hilo (capital da Big Island) depois do tsunami de 1946 (daqui)

O Sismo das Ilhas Aleutas de 1946 ocorreu na proximidade das Ilhas Aleutas, arquipélago do Alasca formado por vulcões de um arco insular associado à zona de subdução da placa do Pacífico sobre a placa norte-americana. Foi a 1 de abril de 1946, às 12.28 horas (UTC), com uma magnitude de 7,8 e o epicentro foi em 52.8°N, 163.5°W (e o hipocentro a 25 km de profundidade), sendo seguido por um tsunami. Este último resultou em 165 mortes: 159 no Havai e seis no próprio Alasca (e em prejuízos de 26 milhões de dólares - valores da época). No Alasca a onda do tsunami teve uma altura de pelo menos 35 m e no Havai, na Big Island, teve uma altura máxima de 8,1 m e seis ou sete ondas, com intervalos de 15/20 minutos.

O tsunami foi estranhamente forte para o tamanho do terremoto; foi a última vez que um sismo abaixo de magnitude 9,0 causou mortes através de um tsunami longe da área do sismo. Vários cientistas acreditam que o tsunami pode ter sido causado por um deslizamento de terra submarino causado pelo sismo. O tamanho e efeitos do tsunami levou, em 1949, à criação do Pacific Tsunami Warning Center, tendo este poupado, ao longo da sua existência, imensas vidas com os seus alertas.

   

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A maré negra do Exxon Valdez começou há 29 anos

Exxon Valdez (anteriormente conhecido também como Dong Fang Ocean, Exxon Mediterranean, SeaRiver Mediterranean, S/R Mediterranean e Mediterranean) foi um navio petroleiro que ganhou notoriedade em 24 de março de 1989, quando 50.000 m³ a 150.000 m³ (aproximadamente 257.000 barris) do petróleo que transportava foram lançadas ao mar, na costa do Alasca, depois de o navio encalhar na Enseada do Príncipe Guilherme (Prince William Sound). Em conseqüência, houve um grande desastre ambiental. Centenas de milhares de animais morreram nos meses seguintes. De acordo com as estimativas, morreram 250.000 pássaros marinhos, 2.800 lontras marinhas, 250 águias e 22 orcas, além da perda de milhares de milhões de ovos de salmão. Foi o segundo maior derramamento de petróleo da história dos Estados Unidos. Na época, o navio pertencia à ExxonMobil.

Em 2002, a União Europeia proibiu a utilização de navios petroleiros de casco simples e o “Valdez”, renomeado “Mediterranean”, foi enviado para as águas da Ásia.

Em 2007, o Valdez foi convertido num transportador de minérios e renomeado como “Dong Fang Ocean”.

Em 2011, com o nome de “Oriental Nicety,” o navio foi vendido a uma companhia de demolições indiana, a Priya Blue Industries, a mesma empresa que, em 2006, tinha atraído má fama após terem afundado um navio que continha amianto.

Em 2012 o “Oriental Nicety” foi desmantelado na Índia.

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O Alasca mudou de dono há 150 anos

O Alasca, à esquerda, em vermelho, com a sua localização na América do Norte

Em 1867, os Estados Unidos da América compraram o território do Alasca ao Império Russo. A operação foi conduzida pelo Secretário de Estado norte-americano William Henry Seward.

À época, a transação foi considerada absurda e era referida como "a loucura de Seward" (William H. Seward's folly). O território comprado, com área aproximada de 1.600.000 km² constitui o atual estado norte-americano do Alasca.

O Império Russo estava em dificuldades financeiras e em vias de perder o território do Alasca sem compensação em algum futuro conflito, sobretudo para o rival da época, o Império Britânico, que detinha o vizinho Canadá e cuja possante Royal Navy poderia facilmente tomar o controle da costa, de defesa difícil para a Rússia. O Czar Alexandre II decidiu então vender o território aos Estados Unidos e encarregou o seu embaixador, o barão Edouard de Stoeckl, de abrir negociações com o Secretário de Estado William Seward, de quem era amigo, no início de março de 1867.
As negociações concluíram-se após discussões que duraram uma noite inteira e a assinatura do tratado foi feita às 4 horas da manhã de 30 de março com um preço de compra de 7.200.000 dólares americanos. A opinião pública americana foi muitíssimo desfavorável a esta compra.
O Senado dos Estados Unidos da América ratificou o tratado a 9 de abril de 1867, por 37 votos a favor e 2 contra.
Estima-se que o Alasca contava na altura com 2.500 russos ou mestiços e 8.000 aborígenes, no total mais de 10 000 habitantes, sob o comando direto da companhia russa das peles, e cerca de 50.000 esquimós viviam sob essa jurisdição.
Os europeus viviam em 23 povoações sitas nas ilhas ou na costa. Em pequenos postos, havia quatro ou cinco russos que se encarregavam da compra e armazenamento de peles trazidas pelos nativos e do reabastecimento de navios que vinham buscar a mercadoria. Havia duas vilas principais. A primeira, New Archangel, atualmente Sitka, foi fundada em 1804, como base de apoio ao rentável negócio de peles de leão marinho. Tinha cerca de 116 barracões que abrigavam 968 habitantes. A segunda era Saint-Paul, na ilha Kodiak, que, com 100 barracões e 283 habitantes, era o centro da indústria de peles de foca.
O nome aleúte Alasca foi escolhido pelos americanos. A cerimónia de transferência teve lugar em Sitka, em 18 de outubro de 1867. Soldados russos e americanos desfilaram junto à casa do governador; a bandeira russa foi arriada e a americana hasteada e saudada por salvas de artilharia. O capitão Alexis Pestchouroff disse "General Rousseau, pela autoridade de sua Majestade, o Imperador da Rússia, transfiro aos Estados Unidos da América o território do Alasca". Em retribuição, o general Lovell Rousseau aceitou o território. Numerosos fortes e fortins, construções de madeira, foram cedidos aos americanos. As tropas ocuparam as casernas e o general Jefferson C. Davis estabeleceu a sua residência na casa do governador. A maior parte dos russos voltou ao seu país, salvo alguns comerciantes e homens do clero.
O Alaska Day celebra a transferência formal do Alasca, que ocorreu a 18 de outubro de 1867. Hoje em dia, o Alasca celebra o dia da compra, o Seward's Day, na última segunda de março.
A data de 18 de outubro de 1867 é do calendário gregoriano, e a hora, 9:01:20, hora de Greenwich, teve efeito no dia seguinte no Alasca para substituir o calendário juliano e a hora de 14:58:40 "de avanço" sobre a hora de Greenwich. Para os russos, a transferência teve lugar a 7 de outubro de 1867.

Cheque utilizado pelo governo dos Estados Unidos para a compra do Alasca

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