In July 1958, an earthquake triggered a landslide in Lituya Bay that generated a megatsunami. It was the largest tsunami in recent history. Lituya Bay is located in Alaska. The height of the initial wave was over 500 meters (1700 feet).
Photo: debris from the rockfall that caused the 1958 Lituya Bay tsunami in Alaska (Creative Commons: Richard Droker).
Lituya Bay is a t-shaped bay with a narrow inlet to the ocean. It has a depth of 220 meters.
The 1958 earthquake had a magnitude of 8.3 on the Richter scale. As a result of this intensity, the earthquake triggered a rockslide. Over 30 million tons of rock fell into the bay and displaced a large amount of water. This displacement caused the tsunami.
The megatsunami caused five deaths.
Eyewitness to the Megatsunami
Video: BBC video of the Alaskan Super Wave (source: YouTube).
Megatsunami History of Lituya Bay
The typical tsunami has a small initial wave height in the ocean. On the other hand, a megatsunami has a large initial wave height. Heights in the hundreds of meters may occur. This super tsunami is triggered by an impact. The impact may be from a landslide or a meteor.
The 1958 megatsunami was not the first in the bay. Similar events were recorded in 1854, 1899 and 1936.
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Mega Tsunami with 500-Foot Waves Swallowed Ancient Island, Live Science.