The1964 Alaska earthquake, also known as theGreat Alaska earthquake andGood Friday earthquake, occurred at 5:36 PMAKST onGood Friday, March 27, 1964.^[2] Across south-centralAlaska, ground fissures, collapsing structures, andtsunamis resulting from the earthquake caused about 139 deaths.^[3]

1964 Alaska earthquake

Fourth Avenue inAnchorage, Alaska, looking east from near C Street. The southern edge of one of severallandslides in Anchorage, this one covered an area of over a dozen blocks, including five blocks along the north side of Fourth Avenue. Most of the area was razed and made anurban renewal district.
Anchorage
UTC time	1964-03-28 03:36:16
ISC event	869809
USGS-ANSS	ComCat
Local date	March 27, 1964 (1964-03-27)
Local time	17:36:16AKST[a]
Duration	4–5 minutes
Magnitude	Mw 9.2–9.3
Depth	25 kilometers (16 mi)
Epicenter	60°54′29″N147°20′20″W / 60.908°N 147.339°W /60.908; -147.339
Type	Megathrust
Areas affected	United States,Canada
Total damage	$311 million (1964 USD) [$2.94 billion (2022 USD)]
Max. intensity	MMI X (Extreme)
Peak acceleration	0.14-0.18g[1]
Tsunami	Major. Run-up of 67 m (220 ft) at Shoup Bay, Alaska.
Casualties	139

Lasting four minutes and thirty-eight seconds, the magnitude 9.2–9.3megathrust earthquake remains the most powerful earthquake ever recorded inNorth America,^[2][4][5] and thesecond most powerful earthquake ever recorded in the world since modern seismography began in 1900.^[6] Six hundred miles (970 km) of fault ruptured at once and moved up to 60 ft (18 m), releasing about 500 years of stress buildup.Soil liquefaction, fissures, landslides, and other ground failures caused major structural damage in several communities and much damage to property.Anchorage sustained great destruction or damage to many inadequatelyearthquake-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 alongKnik Arm. Two hundred miles (320 km) southwest, some areas nearKodiak were permanently raised by 30 feet (9 m). Southeast of Anchorage, areas around the head ofTurnagain Arm nearGirdwood andPortage dropped as much as 8 feet (2.4 m), requiring reconstruction and fill to raise theSeward Highway above the new hightide mark.

InPrince William Sound,Port Valdez suffered a massive underwater landslide, resulting in the deaths of 32 people between the collapse of theValdez 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 ofChenega, killing 23 of the 68 people who lived there. The survivors out-ran the wave, climbing to high ground. Post-quake tsunamis severely affectedWhittier,Seward,Kodiak, and other Alaskan communities, as well as people and property inBritish Columbia,Washington,Oregon, andCalifornia.^[7] Tsunamis also caused damage inHawaii andJapan. Evidence of motion directly related to the earthquake was also reported fromFlorida andTexas.

On March 27, 1964, at 5:36 p.m. AKST (March 28, at 3:36 a.m.UTC),^[a] afault between thePacific andNorth Americanplates ruptured nearCollege Fjord in Prince William Sound. Theepicenter of the earthquake was 12.4 mi (20.0 km) north ofPrince William Sound, 78 miles (126 km) east of Anchorage and 40 miles (64 km) west of Valdez. The focus occurred at a depth of approximately 15.5 mi (24.9 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.^[8] Large rockslides were also caused, resulting in great property damage.Vertical displacement of up to 38 feet (12 m) occurred, affecting an area of 100,000 square miles (260,000 km²) within Alaska.

Studies ofground motion have led to apeak ground acceleration estimate of 0.14–0.18g.^[1] The earthquake was assigned a maximumModified Mercalli intensity of X (Extreme). Shaking was felt across much of Alaska and parts of westernYukon andBritish Columbia in Canada.^[9]

The Alaska earthquake was asubduction zone (megathrust) earthquake, caused by an oceanic plate sinking under a continental plate. The fault responsible was theAleutian 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.^[10] Uplift occurred across 520,000 km² (200,000 sq mi) from southern Kodiak to Prince William Sound and further east of the sound. The maximum uplift was in Montague Island, where the ground was raised 13–15 m (43–49 ft) relative to sea level. The uplift also affected Kodiak, Sitkalidak, and Sitkinak islands. Subsidence was observed for 285,000 km² (110,000 sq mi) from north and west of the sound, in Chugach Mountains, most of Kenai Peninsula, and almost all the Kodiak Island group.^[9]

Two types of tsunami were produced by this subduction zone earthquake. There was a tectonic tsunami produced in addition to about 20 smaller and local tsunamis. These smaller tsunamis were produced by submarine and subaerial landslides and were responsible for the majority of the tsunami damage. Tsunami waves were noted in over 20 countries, including Peru, New Zealand, Papua New Guinea, Japan, Mexico, and in thecontinent of Antarctica. The largest tsunami wave was recorded inShoup Bay, nearValdez, Alaska, with a height of about 220 ft (67 m).^[3]

As a result of the earthquake, 139 people are believed to have died: Fifteen died as a result of the earthquake itself and another 124 died from the subsequent tsunamis in Alaska, Oregon, and California.^[3] Five died from the tsunami inOregon,^[3][12] and 13 died from the tsunami inCalifornia, mostly in or nearCrescent City.^[3][13][14] Property damage was estimated at $116 million^[3] ($871 million in 2023 dollars).^[15]

Most damage occurred in Anchorage, 75 mi (121 km) northwest of the epicenter. Anchorage was not hit by tsunamis, butdowntown Anchorage was heavily damaged, and parts of the city built on sandy bluffs overlying "Bootlegger Coveclay" nearCook Inlet, most notably the Turnagain neighborhood, sufferedlandslide damage. The neighborhood lost 75 houses in the landslide, and the destroyed area has since been turned intoEarthquake Park.^[16] TheGovernment Hill school suffered from theGovernment Hill landslide, leaving it in two jagged, broken pieces. Land overlooking theShip Creek valley near theAlaska 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.^{[citation needed]} The concrete control tower atAnchorage International Airport collapsed, killing the controller on the top floor, as well as trapping two cooks on the first floor, who were later rescued.^{[17][18]: 120}

One house on W. 10th Avenue suffered peripheral damage, but only one block away the recently completed (and still unoccupied) Four Seasons Building on Ninth Avenue collapsed completely, with the concrete elevator shafts sticking up out of the rubble like a seesaw.^{[citation needed]}

The hamlets ofGirdwood andPortage, located 30 and 40 mi (48 and 64 km) southeast of central Anchorage on theTurnagain 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.^{[citation needed]}

Most coastal towns in the Prince William Sound,Kenai Peninsula, andKodiak Island areas, especially the major ports ofSeward,Whittier andKodiak were heavily damaged by a combination of seismic activity,subsidence, post-quake tsunamis and/or earthquake-causedfires. Valdez with 32 dead was not totally destroyed, but after three years, the town relocated to higher ground four miles (6.4 km) west of its original site. SomeAlaska Native villages, includingChenega andAfognak, were destroyed or damaged.^{[citation needed]} The earthquake caused theballistic missile detection radar ofClear Air Force Station to go offline for six minutes,^[19] the only unscheduled interruption in its operational history. NearCordova, theMillion Dollar Bridge crossing theCopper River also suffered damage, with Span #4 slipping off its pylon and collapsing. The community ofGirdwood was also confined to the southern side of the Seward Highway when water rushed into Turnagain Arm and flooded or destroyed any buildings left standing to the north of the highway. 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 covered by thousands of years of sediment and glacial deposits.^{[citation needed]}

A 4.5 ft (1.4 m) wave reachedPrince Rupert, British Columbia, just south of theAlaska Panhandle, about three hours after the earthquake. The tsunami then reachedTofino, on the exposed west coast ofVancouver Island, and traveled up afjord to hitPort Alberni twice, washing away 55 homes and damaging 375 others. The towns ofHot Springs Cove,Zeballos, andAmai also saw damage.^[20] The damage in British Columbia was estimated at CA$10 million ($96 million in 2023 Canadian dollars or $94 million in 2024 US dollars).^[21][22]

Ten people were killed by the tsunami inCrescent City, California, and one other man was killed nearRequa, California after being swept out to sea while fishing in theKlamath River.^[23][24] Four children were killed while camping with their parents on the Oregon coast atBeverly Beach State Park.^[24][25] An additional death that is sometimes attributed to the tsunami took place inBolinas, California; a fisherman wading into a seaside channel at Duxbury Point was swept into the ocean by a strong surge that took place 13 hours after the initial tidal surge.^[24][26] Crescent City was particularly hard-hit, with 30 blocks destroyed, representing half of the city's waterfront business district.^[27] The total damage to Crescent City was estimated at $7.4 million^[28] ($76 million in 2025 dollars). Other coastal towns and harbors in thePacific Northwest,California, andHawaii were damaged, often extensively. Damage to harbors and boats occurred as far south asLong Beach.^[24][29] Effects of the earthquake were even noted as far east asFreeport, Texas, where tide gauges recorded waves similar toseismic surface waves.^[30]Seiches were detected in wells in countries around the world, including England, Namibia, and Australia.^[18]: 145

There were hundreds of aftershocks in the first weeks following the main shock. In the first day alone, eleven major aftershocks were recorded with a magnitude greater than 6.0. Nine more struck over the next three weeks. In all, thousands of aftershocks occurred in the months following the quake, and smaller aftershocks continued to strike the region for more than a year.^[29]

Alaska had never experienced a major disaster in a highly populated area before, and had very limited resources for dealing with the effects of such an event. In Anchorage, at the urging of geologistLidia Selkregg, the City of Anchorage and the Alaska State Housing Authority appointed a team of 40 scientists, including geologists, soil scientists, and engineers, to assess the damage done by the earthquake to the city.^[31] The team, called the Engineering and Geological Evaluation Group, was headed byDr. Ruth A. M. Schmidt, a geology professor at theUniversity of Alaska Anchorage. The team of scientists came into conflict with local developers and downtown business owners who wanted to immediately rebuild; the scientists wanted to identify future dangers to ensure that rebuilt infrastructure would be safe.^[32] The team produced a report on May 8, 1964, just a little more than a month after the earthquake.^[31][33]

The United States military, which has a large active presence in Alaska, also stepped in to assist within moments of the end of the quake. TheU.S. Army rapidly re-established communications with the lower 48 states, deployed troops to assist the citizens of Anchorage, and dispatched a convoy to Valdez.^[34] On the advice of military and civilian leaders, PresidentLyndon B. Johnson declared all of Alaska a major disaster area the day after the quake.

TheU.S. Navy andU.S. Coast Guard deployed ships to isolated coastal communities to assist with immediate needs. Bad weather and poor visibility hampered air rescue and observation efforts the day after the quake, but on Sunday the 29th the situation improved and rescue helicopters and observation aircraft were deployed.^[34] A military airlift immediately began shipping relief supplies to Alaska, eventually delivering 2,570,000 pounds (1,170,000 kg) of food and other supplies.^[35]

Broadcast journalistGenie Chance assisted in recovery and relief efforts, staying on theKENI air waves over Anchorage for more than 24 continuous hours as the voice of calm from her temporary post within the Anchorage Public Safety Building.^[36] She was effectively designated as the public safety officer by the city's police chief.^[36] Chance provided breaking news of the catastrophic events that continued to develop following the magnitude 9.2 earthquake, and she served as the voice of the public safety office, coordinating response efforts, connecting available resources to needs around the community, disseminating information about shelters and prepared food rations, passing messages of well-being between loved ones, and helping to reunite families.^[37]

In the longer term, theU.S. Army Corps of Engineers led the effort to rebuild roads, clear debris, and establish new townsites for communities that had been completely destroyed, at a cost of $110 million.^[35] TheWest Coast and Alaska Tsunami Warning Center was formed as a direct response to the disaster. Federal disaster relief funds paid for reconstruction as well as financially supporting the devastated infrastructure of Alaska's government, spending hundreds of millions of dollars that helped keep Alaska financially solvent until the discovery of massive oil deposits atPrudhoe Bay. At the order of theU.S. Defense Department, theAlaska National Guard founded theAlaska Division of Emergency Services to respond to any future disasters.^[34]

• List of earthquakes in Alaska

• M9.2 Alaska Earthquake and Tsunami of March 27, 1964, US Geological Survey, Earthquake Hazards Program
• 1964 Great Alaska Earthquake, Alaska Division of Homeland Security & Emergency Management.
• 1964 M9.2 Great Alaska Earthquake, Alaska Earthquake Center, University of Alaska, Fairbanks.
• The Great Alaska Earthquake & Tsunami March 27, 1964, Disaster Pages of Dr. George Pararas-Carayannis
• Though the Earth Be Moved: The Alaskan Earthquake (film), Office of Civil Defense (DOD CD 20-238), 1965. (45 minutes)
• Event Bibliography for 1964 Alaska earthquake, International Seismological Centre