The 1964 Good Friday Earthquake was an event involving an earthquake, landslides, and a tsunami – the latter which affected the northern shore of California. The magnitude of the earthquake was recorded at 9.2, considered extreme, and was the largest earthquake to hit the United States, and the second largest ever recorded. Overall, there was “heavy damage on the coastal towns of Valdez, Whittier, Seward, and Kodiak” (Taylor), as well as the islands off the Kenai Peninsula, including Kodiak and Middleton Island. Valdez was hit the hardest, as the entire town was flooded by the tsunami, and has since been relocated and rebuilt east of the Prince William Sound region and north of Middleton Island.
There were 139 reported deaths from the event, mostly due to the tsunami that reached land quickly, with a recorded height of 220 feet (67 meters), nearly engulfing small buildings and homes in towns rapidly. 106 deaths were officially reported from the tsunami, with an additional 13 from the water that submerged northern shores of California (USGS). The rest died in the ensuing shockwaves and land separation that collapsed buildings, separated bridges, and destroyed asphalt-paved roads. There were also several landslides in various parts of Alaska shortly after the earthquake, and oil tank fires that caused several deaths and damage in the dock areas of Whittier.
The event started at approximately 5:36 PM on the early evening of March 7 and ended four and a half minutes later. Specifically, “the earthquake rupture started 25 km beneath the surface, with its epicenter about 6 miles (10 km) east of the mouth of College Fiord, 56 miles (90 km) west of Valdez, and 75 miles (120 km) east of Anchorage” (USGS). The Prince William Sound region was reported to be the main area where the epicenter started. Although Alaska was the main area affected by the event and California experienced high water, Australia also reported tremors deep within water wells in some towns.
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The economic consequences of the Good Friday Earthquake were drastic. Several human-made, modern constructions were affected by shockwaves including buildings, railroad stations, factories; schools, parking garages, and entire avenues. The town of Seward, specifically, suffered from a fire that burned its waterfront railroad stations and completely derailed its track foundations. As mentioned before, the town of Valdez was the most affected of any during the event, due to its proximity to the coast where the tsunami caused by the tectonic shift flooded the town within minutes. Entire homes were uprooted, demolished, or buried in waves or crushed by the debris and moist sediments. As a result, the “instability and vulnerability to future tsunamis made the old town site too dangerous to rebuild, so the town was relocated several miles west to more stable ground, and rebuilt” (Taylor). Roads still travel through the area, and vegetation has since grown, but the surface has been deemed too dangerous for building homes.
Similar devastation happened to the neighborhood of Turnagain Heights, which was a sloped land area containing several homes, pavement, and sidewalk. This area was buried or else uprooted by a landslide that occurred just moments after the initial earthquake. It has since been turned into a public park, with few neighboring homes on the border. The neighborhood now exists as a flattened surface area much safer than its original and is considered safe for residency. Other landslides took place during and after the initial earthquake, but the slide affecting Turnagain Heights was the most drastic. The majority of highways, streets and towns were successfully repaired by the disaster, but the estimated cost in losses was $311 million (Galvin).
The earthquake was caused by a sudden shift in plate tectonics. Specifically, the Pacific Plate, which resides in the water miles from the Alaskan shore, converged beneath the North American Plate (where Alaska exists), and created a subduction zone. This subduction zone caused a sudden collision in plate movements, generating a ‘ripple’ effect that formed the tsunami. The convergence of these two plates was made possible by the Aleutian Trench, which sits below the depths of the Pacific and North American plates and created a megathrust. The oceanic trench was originally a string of volcanic islands and has consistently created earthquakes in other parts of Alaska, and also in Hawaii. Due to this earthquake, “the occurrence of tens of thousands of aftershocks indicates that the region of faulting extended about 620 miles (1,000 km) along the North Pacific Plate” (Britannica), and thus agitated the Aleutian Trench. No North American earthquake has since been as devastating.
Initially, earth scientists were unsure of how to explain the massive disaster. Using the Richter Scale, they were able to map out the amplitude of the seismic waves but were puzzled to find “vertical shifts of the Earth’s surface over an area two-thirds the size of California” (USGS). Several observations and theories were proposed, but it took many years to conclude that the subduction zone which had occurred is part of a pattern where earthquakes generate uplift of the coastline above the shallowest and most seaward part of a rupture – a process which would reverse in approximately every 600 years (USGS). This process is part of a continual cycle of subsistence and submergence that the earth will continue to undergo in periods of 5,000 years (and has undergone in the past 5,000). If there were to be another great earthquake like this in Alaska, it would not be in our lifetime.
However, evidence of soil failure from other earthquakes in places like Japan indicate frequent seismic activity that triggers water in soil and loosens foundations. In some case, as with Alaska’s, entire foundations may sink into the soil or be shaken when water enters the land due to rumbling. This may be hazardous even when earthquakes do not occur but threaten to bring tsunamis onto land and flood harbor towns. This process of liquefication was the case with the coast of California, where sixteen people died from the tsunami waves despite not having been directly affected by the upheaval of land mass generated by the Good Friday earthquake.
Before the 1964 disaster, little was observed about how earthquakes are connected to seafloor spreading. But the “1964 Great Alaska Earthquake was one of the first events to demonstrate to scientists that an earthquake may cause changes to seafloor depth that generate transoceanic tsunamis” (USGS). Because of this, scientists now understand how plate tectonics can cause vertical and horizontal shifts on the ocean seafloor that can extend transatlantic borders. Preventive measures are now installed in Alaska like seismographs to measure the seismic activity in the area should another unprecedented earthquake occur. More specifically, modern-day Alaskans are concerned more about ensuing tsunamis from seismic activity rather than actual earthquakes.
For this, the government has mitigated tsunami risk “by mapping inundation zones, planning evacuation routes, educating coastal communities and their visitors, constructing tsunami-resistant infrastructure, and creating earthquake and tsunami warning systems and centers” (Britannica). Alaskans have become significantly more prepared for coastal disasters, and as mentioned before, many new communities have been constructed on safer land with sturdier soil. Many exist on elevated land such as hills or slopes, with easily escapable roads.
This was not the case in 1964. The Good Friday earthquake happened extremely fast, but in some areas, people could have escaped safely had the proper safety measures been put into place. One of the biggest was the fact that too many homes in Whittier, Valdez, and Chenega resided in coastal areas too close to the water. Naturally, when the tsunami engulfed the area, residents were unable to evacuate quickly, and “these sobering fats show that residents of any coastal community need to immediately head to higher ground when they feel seismic shaking” (USGS). Unfortunately, no instruments were good enough in 1964 to measure such seasick activity. Today, ground-motion data can be detected by Global Positioning System (GPS), and it is much easier to detect incoming earthquakes. Because of the Good Friday earthquake, Alaska and other states have cooperated to create the Advanced National Seismic System and has prepared the National Seismic Hazard Maps (USGS).
The Good Friday earthquake may be one of the true natural disasters of our time, because although Alaskans had construct cities close to the water, the destructive four-and-a-half-minute disaster happened so fast that hardly any citizens were able to respond appropriately. The city should have had warnings and emergency drills in place, but technology was inadequate in 1964 to properly prepare for such disasters. If there is one main thing to be learned, it is that even the slightest tremors of seismic activity can generate liquefication an fluctuating water levels, leading possibly to tsunamis absent of earthquakes. Any and every town beside the coast within a subduction zone ought to have emergency protocols and roads with access to higher ground.
References
- Christopherson, R. Elemental Geosystems (2016), pp. 20-27.
- Berg, E., Dial, R., Klein, E., Reply to comment by Gracz on ‘Wetland drying and succession across the Kenai Peninsula Lowlands, south-central Alaska.” NRC Research Press (2010). Retrieved from cjr.nrc.ca.
- Galvin, John. Great Alaskan Earthquake and Tsunami: Alaska, March 1964. In Popular Mechanics. Retrieved from https://www.popularmechanics.com/
- science/environment/a1967/4219868/
- Peters, J., Schmidtlein, M., Wood, N. Changes in population evacuation potential for tsunami hazards in Seward, Alaska, since the 1964 Good Friday earthquake. Natural Hazards (2014) 70: 1031-1053. Retrieved from www.engineeringvillage.com.ezproxy2.library.edu/search.
- Alaska earthquake of 1964. In Britannica. Retrieved from https://www.britannica.com/event/Alaska-earthquake-of-1964.
- The Great M9.2 Alaska Earthquake and Tsunami of March 27, 1964. (n.d.). In USGS. Retrieved 4 September 2018, from http://libguides.gwumc.edu/c.php?g=27779&p=170342.
- Taylor, Alan. 1964: Alaska’s Good Friday Earthquake. The Atlantic (2014). Retrieved from https://www.theatlantic.com/photo/2014/05/1964-alaskas-good-friday- earthquake/100746/.
