The biggest wave ever recorded measured 1,720 feet

Surfing
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, in 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 seven miles (11.2 kilometers) long, 2 miles (3.2 kilometers) 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.

Total Obliteration

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.

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.

"Edrie" was anchored at Anchorage Cove, on the south side of the bay, around half a mile from the mouth. 

"Sunmore" and "Badge" chose the opposite side of the bay, behind the spit that extended most of the way across the mouth of the bay.

The occupants of "Edrie" and "Badge" were able to surf the massive wave as it swept them above the trees and washed them back into the bay.

The two people on "Sunmore" 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," described Howard G. Ulrich, the owner of "Edrie" and one of the survivors.

"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 [548 meters]; the water splashed there."

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

Lituya Bay: the T-shaped Alaskan bay recorded the biggest wave ever | Photo: U.S. Geological Survey

A Haunting Vision

The "Badger," a trolling boat anchored in Anchorage Cove near the western side of Lituya Bay's entrance, was also lucky.

"Suddenly, the glacier dropped back out of sight, and there was a big wall of water going over the point," explained Bill and Vivian Swanson, the owners of the "Badge."

"The wave started for us right after that, and I was too busy to tell what else was happening up there."

In the blink of an eye, their boat was going over trees and large rocks before crash-landing. Bill and Vivian found themselves surrounded by acres of wood debris but were later found by a rescue team.

According to the eyewitnesses, the wave crest was only between 25 and 50 feet (7.6-15.2 meters) wide, with the front slope was steeper than the back of the wave.

Bill Swanson only returned to Lituya Bay in May 1962.

However, as he was entering the bay, he suffered a heart attack and passed away.

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).

In 2019, scientists from Universidad de Málaga, Spain, developed an updated 3D simulation of the landslide-generated megatsunami.

The team used an accurate reconstruction of the initial slide and a shallow-water model that can reproduce how the energy released by the landslide is transmitted to the water and then propagates.

Learn how waves are formed.