1964

1964 Alaska earthquake

The Great Alaska earthquake and tsunamis strike

The shaking lasted about four and a half minutes — long enough that in some places the local tsunami arrived before the ground stopped moving.

5:36 p.m. on Good Friday

At 5:36 p.m. Alaska Standard Time on Good Friday, 27 March 1964, a magnitude-9.2 megathrust earthquake began beneath the Prince William Sound region, about 25 kilometres below the surface.

Roughly four and a half minutes of shaking ruptured about 580 miles of fault, causing landslides, submarine slumps, liquefaction, subsidence and uplift across south-central Alaska.

In Anchorage, major ground failures damaged or destroyed roughly 30 downtown blocks and devastated parts of Government Hill and Turnagain Heights, where about 200 acres and 75 homes went down with the bluff.

Waves before the shaking stopped

Submarine landslides triggered by the quake produced local tsunamis that reached some communities within minutes — in places before the ground had stopped moving.

At Chenega the waves arrived within minutes, destroyed all but two buildings and killed 23 of the village's 75 inhabitants, according to a modern USGS reconstruction. The trans-Pacific tsunami caused further deaths and damage along the coasts of Oregon and northern California.

The official counts disagree

The two principal compilations differ. The current USGS summary gives 131 deaths — 115 in Alaska and 16 in Oregon and California — while NOAA's NCEI database gives 139, of which 124 are attributed directly to tsunamis.

Eleven aftershocks above magnitude 6.0 followed during the first day. President Johnson declared the entire state a major disaster area on 28 March.

Sources

Researched 23 Aug 2026 8 sources 2 audit passes Date corrected

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date corrected. The research places this at 1964-03-27.

What the sources leave uncertain

The local civil date is securely March 27; the instrumental UTC date is March 28. Both appear in catalogs because Alaska Standard Time was nine hours behind UTC.
Official casualty compilations conflict. The current USGS summary uses 131 deaths, while NOAA's NCEI database uses 139, of which 124 are assigned to tsunamis. The listed figure of 125 is supported by neither compilation.
Tsunami and earthquake-death classifications differ among official datasets, producing totals such as 119, 122, or 124 tsunami deaths.
USGS historical treatments have assigned maximum Modified Mercalli intensity X, while the modern USGS event page displays IX. Intensity should therefore be attributed to a specific assessment.