When most people think of a tsunami, they picture the 2004 Indian Ocean disaster or the 2011 wall of water in Japan. Those were horrific, wide-scale tragedies. But if you’re asking about pure, terrifying scale—the kind of wave that literally scrapes the trees off a mountain—you have to look at a remote spot in Alaska.
It happened in 1958.
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Lituya Bay is a T-shaped fjord located on the coast of the Alaska Panhandle. It’s beautiful, isolated, and incredibly dangerous. On July 9, 1958, an earthquake with a magnitude of 7.8 to 8.3 struck along the Fairweather Fault. This wasn't just a shake; it was a massive displacement of Earth. It caused 40 million cubic yards of rock and ice to plunge from a height of 3,000 feet straight into the narrow waters of Gilbert Inlet.
The result? The biggest tsunami ever recorded in modern history.
The 1,720-Foot Wave That Defied Physics
Imagine the Empire State Building. Now, stack another half of it on top. That is the height this water reached.
When that massive rockfall hit the water, it didn't just create a ripple. It created a "megatsunami." The force was so immense that the water surged up the opposite shoreline, reaching a maximum height of 1,720 feet (524 meters). Scientists know this because the wave stripped every single bit of vegetation, soil, and ancient forest off the mountainside. It left a "trimline"—a stark, jagged edge of bare rock where green forest used to be.
Most tsunamis are caused by tectonic shifts on the ocean floor. They have long wavelengths and may only be a few feet high in the open ocean before growing as they hit the coast. Lituya Bay was different. This was a "splash wave."
Surviving the Unsurvivable
You'd think anyone in that bay would be dead instantly. Amazingly, some people lived to tell the story. Howard Ulrich and his seven-year-old son were anchored in the bay on their boat, the Edrie.
Ulrich woke up to the boat shaking violently. He looked toward the back of the bay and saw something that shouldn't exist: a wall of water that looked like a mountain. He later described it as the biggest thing he’d ever seen. He didn't have time to think. He let out the anchor chain, and the Edrie was lifted up, up, and over the crest of the wave. They literally rode the wave over the tops of trees.
The boat survived. They were okay.
Another couple, the Swansons on the Badger, weren't as lucky with their vessel, but they survived too. Their boat was carried over the spit at the mouth of the bay, hitting bottom before it sank. They managed to get into a skiff and were rescued. Sadly, a third boat, the Sunmore, vanished. No trace of the boat or its two passengers was ever found.
Why Lituya Bay Is a "Tsunami Machine"
If you look at the geography, it makes sense why the biggest tsunami ever happened right here. Lituya Bay is a trap. It’s narrow, it’s deep, and it sits right on a major fault line.
Dr. Don Miller of the United States Geological Survey (USGS) was one of the first experts on the scene. He spent years studying why this specific bay produced such monsters. It turns out, 1958 wasn't the first time. There were smaller, yet still massive, waves recorded there in 1853, 1874, and 1936.
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The 1958 event changed how geologists view "megatsunamis." Before this, many scientists were skeptical that a landslide could cause such a massive surge. They thought only subduction zone earthquakes could create major tsunamis. Lituya Bay proved that when you move enough rock into a confined space, the water has nowhere to go but up.
Modern Science and the Megatsunami Myth
There’s a lot of fear-mongering on the internet about "the big one" hitting the East Coast of the U.S. or the UK because of a landslide in the Canary Islands (the Cumbre Vieja volcano). People point to Lituya Bay as proof.
But here is the nuance: Lituya Bay is a closed system. It’s a narrow fjord. In the open ocean, that energy dissipates much faster. While a massive landslide into the Atlantic would be devastating, it likely wouldn't maintain a 1,700-foot height across the entire ocean.
Still, the physics are sobering. Hermann Fritz, a professor at Georgia Tech who specializes in fluid mechanics, has used laboratory tanks to recreate the Lituya Bay wave. His research confirms that the sheer volume of the 1958 landslide, combined with the "gravity-driven" impact, created a near-perfect transfer of energy. Basically, the water didn't have time to get out of the way. It was forced to climb.
The Geology of Fear
- The Fairweather Fault: This is a strike-slip fault, similar to the San Andreas in California. It moves horizontally, which usually doesn't cause tsunamis.
- The Landslide: The earthquake triggered a "subaerial" landslide—rock falling from air into water.
- The Bathymetry: The bay is deep (about 700 feet) but narrows at the entrance, which helped "pile up" the water.
It's sorta weird to think about a place so beautiful being the site of such violence. If you go there today, you can still see the different ages of the trees. The "new" forest is a different shade of green than the old growth that wasn't touched by the water. It’s a living scar.
Comparing the Giants: 1958 vs. 2004
You might wonder why we call Lituya Bay the biggest if the 2004 Indian Ocean tsunami killed hundreds of thousands of people and Lituya Bay only killed five.
It’s all about height vs. impact.
The 2004 tsunami was a global event. It traveled thousands of miles. The waves were "only" about 100 feet high at their peak in Sumatra. But they carried billions of tons of water across entire countries. Lituya Bay was a localized spike. It was the tallest wave ever measured, but its energy stayed mostly within the bay. It’s the difference between a sniper bullet and a massive flood. One is more concentrated; the other is more widespread.
What You Should Do With This Information
Understanding the biggest tsunami ever isn't just about trivia; it's about situational awareness if you live near or travel to coastal regions.
First, realize that "tallest" doesn't always mean "most dangerous." If you are in a coastal area and feel an earthquake that lasts more than 20 seconds, don't wait for an official warning. Move inland or to high ground immediately. In the Lituya Bay case, the wave hit within minutes of the earthquake.
Second, if you’re a hiker or a boater in places like Alaska, Norway, or British Columbia, recognize the signs of unstable slopes. Fjord-heavy regions are the primary "hot spots" for these types of landslide-induced megatsunamis.
Finally, keep an eye on the science coming out of the USGS and the National Tsunami Warning Center. They now use sensors and satellite data to monitor "unstable" mountainsides near water. We are much better at predicting these events than we were in 1958, but nature still has a way of surprising us.
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If you ever find yourself in Southeast Alaska, you can actually take a boat tour or a flight-seeing trip over Lituya Bay. Seeing that trimline in person is the only way to truly grasp the scale. The trees are still growing back, sixty-plus years later. It’s a quiet, haunting reminder that the earth can move in ways we can barely imagine.
Stay informed by checking the NOAA Tsunami Database for historical records of your local coastline. If you live in a high-risk zone, have a "go-bag" ready and know your evacuation route by heart. The survivors of Lituya Bay didn't have time to look at a map; they had to act on instinct.