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The Lituya Bay Disaster
With a maximum perceived intensity of XI (extreme) on the Mercalli intensity scale, the earthquake that hit Lituya Bay, a fjord located on the Fairweather fault, created major landslides from 914 meters and loosened 30.6 million cubic meters of land. The composition of tectonic plates and glacial rockfalls caused the worlds biggest megatsunami.
The Earthquake.
On July 9th 1958, at 22:15:58, a quake with a moment magnitude of 7.8 triggered a subaerial rockslide of 30 million cubic meters (90 million tons) into the narrow fjord of Lituya Bay, Alaska. The impact was audible from 80km in distance. The epicentre of the quake was at a latitude of 58.37 degrees N, longitude of 136.67 degrees W. Residents as far south as Seattle, Washington felt the shock.
The Tsunami.
The megatsunami was caused by the severe rockfalls plunging deep into the bay. Multiple glaciers also collapsed into the bay, creating a tidal wave unforgettable to locals. Two fishermen lost their lives after being caught in the wave and numerous residential buildings were damaged beyond repair. Disaster had struck. Seismologists studied the bay for years, finally concluding that the initial rockfall could have triggered a second submarine slide of glacial sediment capable of generating the wave to its full extent.
The megatsunami that affected Lituya Bay on July 9th 1958 was caused by numerous landslides and rockfalls. The earthquake that generated the subaerial rockfalls had a magnitude of 7.8. Seismologists believe that there was a second submarine landslide, inducing the large wave.
By Ayla
