Imagine standing on a boat in a quiet Alaskan bay. The sun is setting. It’s 1958. Suddenly, the world starts shaking so violently you can't even stand up. Then, you look toward the back of the bay and see something that shouldn't be physically possible: a wall of water that has literally stripped the trees off a mountain 1,700 feet above the shoreline.
That actually happened.
Most people, when they think of the largest tsunami ever recorded, picture the devastating 2004 Indian Ocean disaster or the tragedy in Tohoku, Japan. Those were massive, sure. They were "tectonic" tsunamis that crossed entire oceans. But in terms of pure, raw height—the kind of vertical run-up that defies belief—nothing touches the 1958 event at Lituya Bay. We are talking about a wave that reached $524$ meters (1,720 feet). For perspective, that is taller than the Empire State Building. By a lot.
It’s terrifying. It's also a bit of a geological fluke.
What actually caused the Lituya Bay megatsunami?
Usually, tsunamis are caused by the seafloor shifting. This was different. On the night of July 9, 1958, a magnitude 7.8 earthquake struck the Fairweather Fault. This wasn't just a little rumble; it was a massive tectonic shift that caused a giant chunk of a mountain to fall.
Basically, about 40 million cubic yards of rock—which is roughly the volume of 13,000 Olympic swimming pools—broke loose from a cliff. It fell 3,000 feet straight down into the narrow Gilbert Inlet at the head of Lituya Bay.
Think of it like dropping a massive brick into a bathtub that’s already too full.
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The displacement was instantaneous. The water didn't have anywhere to go but up and out. This created a "megatsunami." Because the bay is narrow and T-shaped, the water was funneled and forced against the opposite slope with incredible pressure. This is where we get that famous 1,720-foot measurement. Scientists like Don Miller from the United States Geological Survey (USGS) arrived shortly after and found a "trimline." This is a clear boundary where the forest had been completely erased, leaving nothing but bare rock where 100-foot-tall spruce trees had stood just hours before.
It was total erasure.
Survival against the odds
There were three boats in the bay that night. You'd assume everyone died. Somehow, they didn't.
Howard Ulrich and his 7-year-old son were on the Edrie. Howard saw the wave coming—a literal mountain of dark water—and managed to get his boat moving. He snapped his anchor chain and steered the boat directly into the swell. They rose. And rose. And rose. They actually rode the wave over the tops of the trees on the shore before the backwash sucked them back into the center of the bay. They survived.
Then there was the Sunmore. Bill and Vivian Swanson were on that boat. Their experience was even more surreal. Their vessel was lifted up by the crest and carried over the spit of land at the entrance of the bay. Bill later described looking down and seeing the tops of the trees beneath his hull. Unfortunately, their boat eventually foundered, and they were lost, but their account—relayed via radio before the end—remains one of the most harrowing eyewitness reports in maritime history.
The third boat, the Badger, also rode the wave. Its occupants, the Wagners, survived after their boat was tossed over the spit and they had to abandon ship into a skiff.
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Why Lituya Bay is a "Tsunami Lab"
Geologists are obsessed with this place. It’s not the first time it happened there, and it won't be the last. Lituya Bay is a perfect trap. It sits right on a major fault line, it has steep walls, and it’s deep.
Researchers like Dr. Hermann Fritz have used hydraulic modeling to recreate the event. They found that the sheer velocity of the landslide was the key. When the rock hit the water, it trapped a cushion of air underneath it, which sounds weird, but it actually increased the "splash" effect.
- The wave didn't travel across the ocean; it dissipated quickly.
- The damage was localized but absolute.
- If this happened in a populated area like Vancouver or Seattle, the death toll would be in the millions.
Thankfully, Lituya Bay is incredibly remote. It’s part of Glacier Bay National Park in Alaska. Even today, very few people go there. If you do visit, you can still see the trimline. The "new" trees are a different shade of green than the old-growth forest higher up. It’s a permanent scar on the landscape.
Other contenders for the "largest" title
Sometimes people get confused by the terminology. If you’re looking for the largest tsunami ever recorded in terms of "most distance traveled," 1958 isn't it.
The 1960 Valdivia earthquake in Chile produced waves that killed people in Hawaii and Japan. The 2004 Boxing Day tsunami killed over 230,000 people. Those are "big" in terms of impact and scale. But Lituya Bay is the undisputed king of height.
There's also the "Storegga Slide" that happened about 8,000 years ago off the coast of Norway. That was an underwater landslide that sent a massive wave crashing into Scotland. Some researchers believe the prehistoric asteroid that killed the dinosaurs caused a tsunami miles high. But we weren't there with measuring tapes for those. For the modern era, Lituya is the gold standard of "holy crap, look at that wave."
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The reality of megatsunami risks today
Kinda makes you wonder if it could happen again elsewhere, right?
Scientists keep a very close eye on places like Cumbre Vieja in the Canary Islands. There’s a theory—highly debated, honestly—that a massive landslide there could send a megatsunami across the Atlantic to hit the U.S. East Coast. Most experts now think that’s an exaggeration and that the mountain would likely crumble in pieces rather than one giant block.
Still, the Lituya Bay event proved that the "landslide-generated wave" is a specific and terrifying category of natural disaster. It doesn't require a deep-sea earthquake. It just requires gravity and a lot of rock.
What you should actually do with this information
If you're a traveler or someone who spends time on the coast, knowing the difference between a "normal" tsunami and a landslide wave matters.
- Understand the "Feel": In Lituya Bay, the earthquake was the only warning. If you feel ground shaking near a cliff-lined coast or a fjord, don't wait for a siren. Move inland. Immediately.
- Watch the Water: If the tide suddenly disappears (the "drawback"), the wave is minutes away. In Lituya, the wave was so fast there was almost no drawback time.
- Respect the Trimline: If you are hiking in Alaska or Norway and see a weird line where the trees suddenly change age or type along a coast, you are standing in a historic splash zone. Maybe don't camp there.
- Check the USGS Maps: If you live in a coastal area, look up your local "inundation zone." These maps show exactly where the water is expected to go in a worst-case scenario.
The 1958 Lituya Bay wave was a freak occurrence, but it wasn't a "one-off." Nature has a way of repeating itself. We just happened to have people there to witness it and survive to tell us how high the water really went.
Next time you see a skyscraper, look at the roof. Then imagine a wall of water that tall coming at you at 100 miles per hour. That is the reality of the largest tsunami ever recorded. It's a humbling reminder that we're just guests on a very restless planet.
To dig deeper into the actual physics of these waves, you can look up the work of the International Tsunami Information Center. They track these events in real-time and provide the most accurate modeling for coastal communities worldwide.