The biggest wave ever recorded measured 1,720 feet

Waves: the biggest wave ever recorded measured 1,720 feet | Photo: Shutterstock

The biggest wave ever recorded by humans was documented on July 9, 1958, in Lituya Bay, on the southeast of Alaska, when an earthquake triggered a series of events that resulted in a megatsunami.

History and science books consider it to be the largest tsunami of modern times. On July 9, 1958, at 10:15 p.m., a magnitude 7.8 earthquake caused a rockslide of around 40 million cubic yards (30.6 million cubic meters) in the Gilbert Inlet.

The epicenter of the earthquake was on the Fairweather Fault, i.e., in the heart of the 7 miles long, 2 miles wide Lituya Bay.

According to scientists, the rocks, glaciers, and other debris fell from an altitude of approximately 3,000 feet (914 meters), and the consequences were brutal.

The event resulted in the highest wave from a massive tsunami in recorded history. The megatsunami itself measured between 100 feet (30 meters) and 300 feet (91 meters), but the subsequent breaking wave became much bigger.

As the giant mountain of water started traveling across the entire length of the T-shaped Lituya Bay, it reached a peak height of 1,720 feet (524 meters), near the Gilbert Inlet, and destroyed everything around.

Total Obliteration

Soil, plants, and trees were snapped off, and the shorelines were completely obliterated. There were three fishing boats in Lituya Bay at the time of the tsunami.

The occupants in two of them were able to surf the huge wave, as it swept them above the trees and washed them back into the bay. Two people on the other boat were caught by the large tsunami and lost their lives.

"The wave started in Gilbert Inlet, just before the end of the earthquake. It was not a wave at first. It was like an explosion or a glacier sluff. The wave came out of the lower part and looked like the smallest part of the whole thing. The wave did not go up 1,800 feet, the water splashed there," described Howard G. Ulrich, one of the survivors.

"Suddenly the glacier dropped back out of sight, and there was a big wall of water going over the point. The wave started for us right after that, and I was too busy to tell what else was happening up there," explained Bill and Vivian Swanson, who were on their boat anchored in Anchorage Cove near the western side of the entrance of Lituya Bay.

Map of Lituya Bay: the megatsunami started near the Gilbert Inlet | Illustration:

According to the eyewitnesses, the wave crest was only between 25 and 50-foot wide, and the front slope was steeper than the back of the wave.

The event that produced the largest wave ever recorded was later studied and modeled by Hermann M. Fritz (1999), Charles L. Mader and Michael L. Gittings (2002).

Learn how waves are formed.

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