Tsunamis have always been among the most devastating forces on Earth. But on a fateful night in 1958, one tsunami rewrote the record books in the most astonishing way possible.
This monstrous wave, born from a perfect storm of geologic events, reached a height that defied belief and reshaped our understanding of these powerful phenomena.
Its impact was felt not only in the immediate aftermath but also in the decades of scientific research that followed.
The Earthquake That Started It All
The Lituya Bay Tsunami was set in motion by a magnitude 7.8 earthquake that struck along the Fairweather Fault, just 13 miles from the bay in Alaska. The quake lasted several minutes and caused significant geologic changes in the area, including uplift and subsidence.(ref)
The powerful tremors were felt across a vast area of 400,000 square miles, extending as far south as Seattle and as far east as Whitehorse, Yukon, Canada. This seismic event was the strongest to hit the region in over 50 years, surpassing the magnitude 8.2 Cape Yakataga earthquake of 1899.
A Rockslide Heard around the World
The earthquake triggered a massive rockslide on the northeastern shore of Lituya Bay. Approximately 40 million cubic yards of rock plunged from a height of about 3,000 feet into the waters of Gilbert Inlet.
The sheer volume of rock involved in this slide was staggering, equivalent to about 6 million dump truck loads. The impact was so powerful that it generated a local tsunami that would soon become the stuff of legend.
The Birth of a Monster Wave
As the rocks hit the water, they displaced a huge volume of water, creating a megatsunami that quickly gained height and speed. Eyewitnesses described the initial wave as an explosion or a glacier sluff, with water splashing up to 1,800 feet on the surrounding cliffs.
The wave then raced down the entire length of Lituya Bay, scouring the shoreline and uprooting millions of trees in its path.
To reach its peak elevation of 1,720 feet, the tsunami required an immense amount of initial kinetic and potential energy to not only climb the slope but also overcome turbulent dissipation and sediment interaction.
Shallow water wave theory suggests that in the 720-foot depth near the source area, the tsunami’s leading wave would have started to break as it approached the sloping fan on the far side of the fjord.
Riding the Crest of Destruction
Remarkably, there were survivors who rode out the wave and lived to tell the tale. Howard G. Ulrich and his 7-year-old son were anchored in their boat, the Edrie, on the southern side of the bay when the tsunami hit.
Ulrich’s chilling account describes the wave as initially looking like “the smallest part of the whole thing” before it carried their boat up the wave’s crest and deposited them back in the center of the bay. They navigated through the chaotic aftermath, dodging subsequent waves up to 20 feet high until they could safely exit the bay.(ref)
Tragically, another boat anchored near the mouth of the bay was believed to have been sunk by the tsunami, with no known survivors among the two people thought to be on board.
Aftermath & Scientific Significance
The Lituya Bay Tsunami claimed five lives and caused extensive damage to the surrounding area. Evidence of the wave’s destructive power can still be seen today, with a distinct trimline of younger trees marking the path of the tsunami.
This event forced scientists to re-evaluate their understanding of large-wave events and recognize the potential for impact-generated tsunamis.
Geologic evidence suggests that Lituya Bay has experienced at least four similar megatsunamis in the past 150 years, with estimated heights ranging from 200 to 490 feet.
The unique geologic and tectonic conditions of the bay, including its steep walls, flat floor, and location along the Fairweather Fault, make it particularly susceptible to these massive waves.
As a result, Lituya Bay should be considered a dangerous body of water prone to infrequent but incredibly large tsunamis.
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Nancy Maffia
Nancy received a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.
