Edition 1

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The 1964 Great Alaska Earthquake and Tsunami

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A magnitude 9.2 earthquake ruptured the Alaska–Aleutian subduction zone for roughly four and a half minutes, making it the most powerful earthquake recorded in United States history. Shaking, landslides, ground failure, and local and ocean-wide tsunamis devastated communities from Prince William Sound to Kodiak and caused deaths as far away as California.

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27 March 1964

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Prince William Sound rupture zone and south-central Alaska

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Alaska’s coastal communities, ports, railways, and new urban development occupied an active plate boundary whose largest earthquakes were not yet understood through the modern framework of plate tectonics. Tsunami warning infrastructure in North America was also limited.

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The Pacific Plate thrust beneath the North American Plate, abruptly displacing an immense section of the seafloor and coastline. The rupture produced strong, prolonged shaking; submarine and coastal landslides generated additional local waves.

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Tsunamis and fires compounded shaking damage in Valdez, Seward, Whittier, Kodiak, and other communities. Anchorage suffered major landslides and building failures. Reconstruction required relocation, new port facilities, and sustained federal and state support.

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Field evidence helped establish how subduction-zone earthquakes work and informed the emerging theory of plate tectonics. The disaster also drove improvements in land-use planning, earthquake engineering, monitoring, and the tsunami warning system centered in Palmer, Alaska.

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The event made cascading coastal risk visible at continental scale. Its unusually complete scientific record still informs hazard models for communities around the Pacific.

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Earthquake Park in Anchorage preserves part of the Turnagain Heights landslide landscape. Changed shorelines, uplifted terrain, relocated towns, scientific markers, and the National Tsunami Warning Center carry the event into the present.

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Fatality totals vary slightly by source depending on whether indirect deaths and distant tsunami losses are included. The epicenter marker represents the rupture’s starting area, not the enormous full zone of damage.

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Chaos Tourist editorial

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M9.2 Alaska Earthquake and Tsunami of March 27, 1964
On This Day: Great Alaska Earthquake and Tsunami

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