Great Alaskan Earthquake (Napoleon's World)

The Great Alaskan Earthquake, also referred to as the Good Friday Earthquake, was a megathrust earthquake that occurred on March 27, 1964. With a magnitude of 9.2, it was the largest earthquake in Alaskan and North American history, and at the time the second strongest earthquake in recorded history.

The earthquake caused ground fissures, collapsed buildings and tsunamies all around coastal Alaska, causing an estimated 77,000 deaths, in particular in the greater Aleksandrgrad area. It is cited as the single greatest disaster in Alaskan history and occurred in the nation's "Great Dark Year," as Tsar Alexander II would be assassinated only months later.

Due to fissures, liquefaction and mudslides, as well as its proximity to the epicenter, the city of Aleksandrgrad suffered catastrophic damage, in particular due to its poorly engineered high rise tenements and the earthquake striking at 5:26 PM, when most people were at home or on their way home from work in the city's notoriously poorly-built mass transit subway system. Cities on Tsarevitch Sound sustained particularly heavy damage, with several cities (Seravino, Buletkin, Chugach) sinking completely, and cities such as Valdez and Kulukiya suffering extensive damage. Across the Gulf of Alaska, tsunamis and fissures caused enormous damage, in particular at Kodiak, where poorly-constructed high-rise tenements collapsed, much like in Aleksandrgrad.

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 Anasenko Fjord in Tsarevitch Sound. The epicenter of the earthquake was 61°03′N 147°29′W﻿ / ﻿61.05°N 147.48°W﻿ / 61.05; -147.48, 12.4 mi (20 km) north of Tsarevitch Sound, 78 miles (125 km) east of Aleksandrgrad 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.[5] 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.[6]

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. It was a reverse fault caused by a compressional force. This caused much of the uneven ground.

Death toll, damage and casualties
Due to the proximity of the epicenter to Alaska's then-second largest city and then-largest metropolitan region, the damage was enormously catastrophic. Estimates of casualties have typically ranged between 70,000 to 80,000, with the official death toll published by the Alaskan government being 77,455. Along with the deaths in Alaska itself, the tsunamis caused the deaths of about 30 people in Oregon and California.

Aleksandrgrad area
The bulk of the damage occurred in Aleksandrgrad proper and its surrounding region, where about 55,000 people are estimated to have been killed - making the earthquake the greatest single loss of life in Alaskan history. Poorly-built public housing collapsed city-wide, and many such buildings collapsed into other buildings as they fell. Due to the earthquake happening in the early evening when many of the city's residents had just returned home from work or were on their way home, the damage caused by falling buildings was compounded. Most the city's southern portions were devastated and required a complete reconstruction from scratch afterwards. Some portions of the city experienced flooding, although the city itself was not struck by tsunamis. The air traffic control tower at Aleksandrgrad International Airport collapsed and a mudslide damaged much of the airport. Mudslides in northern Aleksandrgrad killed hundreds, and almost 70% of the city's subway tunnels collapsed, killing thousands more. The city experienced systemic fires, often started by gas leaks or spilt oil, for several days afterwards, although the fires did not accrue significant casualties despite consuming much of the city's wreckage. Small suburban towns on the Osarenkov Inlet were wiped out, and hundreds were killed at coastal towns on the Tsarevitch Sound.

With over 50,000 dead and almost 200,000 injured in a region home to just shy of a million, Premier Kirill Osopek declared "the greatest single loss of life in human history, the pearl of Alaska dirtied by the fury of nature."

Elsewhere in Alaska
Tsunamis struck the city of Kodiak and caused rampant damage, with as many as 10,000 of the city's 140,000 residents killed and almost the entire city damaged heavily, and neighboring towns were wiped out along with the businesses that operated there. Bridges around the country collapsed and coastal cities all along the Gulf of Alaska were flooded with tsunamis. Inland, minor quakes caused extensive damage at Feodorograd and Rozangrad, where as many as 2,000 people were killed combined. A ground fissure destroyed an oil refinery plant in Sofiyagrad, which resulted in a major fire that killed upwards 200 people along with those already killed by the tsunami that struck the city's downtown area. While Sitka experienced flooding and a minor rise in water level, there were no casualties in the city and only minor damage in the capital.

Impact
The earthquake is regarded as one of the most significant events in Alaskan history, and is considered the end of Alaska's age of growth and internal achievement that had begun in the late 1940's under Yakov Sighovaryin. In fact, due to the assassination of Tsar Alexander II later in 1964, the early 1960's are regarded as the "Time of Great Sorrow" for the nation.

In particular, the earthquake is often cited for the reason for the Gulf of Alaska's decline as the country's most prominent region. In the late 1960's, the Kialgory-Evgenigrad Corridor would explode in size (Evgenigrad was already Alaska's largest city by 1964) and supplant Aleksandrgrad and the Novorossija region as the commercial and financial hub of the country by the mid-1970's.

The period between 1964 and 1980 saw thousands of Alaskans flock from devastated coastal towns inland, and only Aleksandrgrad would eventually recover its prominence due to its strategic port and historical importance. Kodiak would never again enjoy a population greater than 100,000 and declined as a major shipping and naval center, a decay directly blamed upon the earthquake. For similar reasons, Sitka's population halved by 1975, despite the city avoiding the destruction sustained by other Gulf cities, and Sofiyagrad went from a major commercial and shipping hub in the Yekaterina Islands in the early 1960's with a population of 200,000 to a small fishing town with a population of 65,000 within ten years, all while Evgenigrad, Kialgory, Novominsk, Mikhailgrad and Novostroya enjoyed even more robust growth than they had experienced prior to the quake.