1958 Lituya Bay, Alaska Earthquake And Megatsunami – Wikipedia

The 1958 Lituya Bay earthquake occurred at July 9 at 22:15:58 with an instant magnitude of 7.8 and also a maximum Mercalli intensity of XI (Extreme). The strike-slip earthquake occurred around the Fairweather Fault and triggered a rockslide of 40 million cubic yards (30 million cubic meters and about 90 million tons) in to the narrow inlet of Lituya Bay, Alaska. 1,720 feet (524 meters) in the entrance of Gilbert Inlet. This is actually the largest & most significant megatsunami today; it forced a re-evaluation of large-wave events along with the recognition of impact events, rockfalls, and landslides as factors behind large waves. A 2010 model examined the quantity of infill on to the floor from the bay, that was many times bigger than that of the rockfall alone, as well as the energy and height in the waves. Scientists figured there have been a “dual slide” involving a rockfall which also triggered a release of 5 to 10 times its level of sediment trapped because of the adjacent Lituya Glacier, a ratio comparable with other events where this “dual slide” effect may have happened.

Lituya Bay includes a history of megatsunami events, however the 1958 event was the initial that sufficient data was captured at that time. Lituya Bay is really a fjord on the Fairweather Fault within the northeastern area of the Gulf of Alaska. This is a T-shaped bay having a width of 2 miles (3 km) as well as a amount of 7 miles (11 km). Lituya Bay can be an ice-scoured tidal inlet which has a maximum depth of 722 feet (220 m). The narrow entrance of this bay includes a depth of only 33 feet (10 m). Both arms that induce the top from the T-shape on the bay will be the Gilbert and Crillon inlets and so are an integral part of a trench around the Fairweather Fault. Before 150 years Lituya Bay has already established three other tsunamis of over 100 ft: 1854 (395 ft or 120 m), 1899 (200 ft or 61 m), and 1936 (490 ft or 150 m).

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Near the crest with the Fairweather Mountains sit the Lituya along with the North Crillon glaciers. They’re each about 12 miles (19 km) long and 1 mile (1.6 km) wide having an elevation of 4,000 feet (1,200 m). The retreats of the glaciers form today’s “T” form of the bay, the Gilbert and Crillon inlets. The major earthquake that struck around the Fairweather Fault had an instant magnitude of 7.8 including a maximum perceived intensity of XI (Extreme) for the Mercalli intensity scale. The epicenter of this quake was at latitude 58.37° N, longitude 136.67° W close to the Fairweather Range, 7.5 miles (12.1 km) east of the top trace on the Fairweather fault, and 13 miles (21 km) southeast of Lituya Bay. The shock was felt in southeastern Alaskan cities over a location of 400,000 square miles (1,000,000 km2), as far south as Seattle, Washington, so when asia as Whitehorse, Yukon, Canada.

The earthquake caused a subaerial rockfall within the Gilbert Inlet. Over 30 million cubic meters of rock fell from the height of several hundred meters in to the bay, creating the megatsunami. Two different people from a vessel died due to having been caught by way of a wave inside the bay. In Yakutat, the only real permanent outpost near to the epicenter at that time, infrastructure such as for example bridges, docks, and oil lines all sustained damage. A water tower collapsed, along with a cabin was damaged beyond repair. Sand boils and fissures occurred close to the coast southeast of there, and underwater cables that supported the Alaska Communication System were cut. Lighter damage was also reported in Pelican and Sitka. Following the earthquake it had been observed a subglacial lake, located northwest on the bend inside the Lituya Glacier at the top of Lituya Bay, had dropped 100 ft (30 m). This proposed another possible cause for the production on the 100 ft (30 m) wave which caused destruction up to 1,720 ft (524 m) above the top of bay as its momentum carried it upslope.