Government or official record
On This Day: Great Alaska Earthquake and Tsunami
NOAA National Centers for Environmental Information
Cross-File evidence ledger
Where this source supports the record
Each entry separates the File’s editorial relevance note from its exact, section-level claims. A bibliography link without a direct claim is labeled plainly.
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Natural disasters · 27 March 1964Open File evidence →
The 1964 Great Alaska Earthquake and Tsunami
Prince William Sound rupture zone and south-central Alaska · United States
Why editors use it hereAccount of the tsunami, warning-system legacy, and preserved historical data.
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Quick read
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.
Reviewed 24 July 2026 -
Trigger and conditions
The Pacific Plate thrust beneath the North American Plate, abruptly displacing an immense section of the seafloor and coastline.
Reviewed 24 July 2026 -
Uncertainty
Fatality totals vary slightly by source depending on whether indirect deaths and distant tsunami losses are included.
Reviewed 24 July 2026 -
Why it matters
The event made cascading coastal risk visible at continental scale.
Reviewed 24 July 2026
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Quick read