On a quiet July night in 1958, the world’s tallest wave wasn't out in the middle of the ocean. It was inside a T-shaped fjord in Alaska. Lituya Bay. It sounds like a peaceful place, right? Most of the time, it is. But on July 9, everything changed in less than five minutes. An earthquake roared. A mountain literally fell into the sea. And the resulting splash? It reached 1,720 feet.
To put that into perspective, that is taller than the Empire State Building. It’s taller than the Willis Tower in Chicago. If you stood at the base of that wave, you wouldn’t be looking at water; you’d be looking at a wall of liquid gravity higher than most skyscrapers on the planet. This is the story of what was the largest tsunami ever documented by science, and honestly, the details are scarier than any Hollywood disaster flick.
The Night the Mountain Fell
It started with a massive 7.8 magnitude earthquake along the Fairweather Fault. This wasn't just a little shaking. It was a violent, earth-shattering jolt that lasted for about two minutes. Deep in the heart of Lituya Bay, at a spot called Gilbert Inlet, the side of a mountain couldn't take the stress anymore.
Basically, 40 million cubic yards of rock—that's roughly 90 million tons—sheared off a 3,000-foot slope and slammed straight down into the water.
Imagine dropping a giant brick into a bathtub. The water doesn't just ripple; it shoots up the sides. That is exactly what happened here, but on a geological scale. The displaced water didn't have anywhere to go because the bay is so narrow. It surged up the opposite headland with so much force that it stripped every single tree, every bit of soil, and even the moss off the rocks up to that 1,720-foot mark.
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Geologists call this "run-up." It’s the highest point the water reaches on land. When scientists like Don Miller flew over the bay the next day, they were stunned. They saw a "trimline"—a sharp, terrifying boundary between the green forest above and the bare, grey rock below where the wave had quite literally power-washed the mountain.
Survival Against All Odds: The Boats in the Bay
Most people think a wave that big would kill everyone for miles. Surprisingly, only five people died. Why? Because Lituya Bay is remote. There were only three small fishing boats anchored in the water that night.
The stories from the survivors are kind of hard to wrap your head around. Take Bill and Vivian Swanson on their boat, the Badger. They were asleep when the quake hit. Bill later said he saw the Lituya Glacier "rise up in the air" and jump around like crazy. Then, a wall of water came for them.
The wave picked up the Badger and carried it—stern first—right over the top of La Chaussee Spit. This is a strip of land covered in forest at the entrance of the bay. Bill said he looked down from his boat and saw the tops of 80-foot spruce trees passing underneath him. The wave basically surfed their boat over a forest and dumped them into the open ocean on the other side. They survived in a skiff, though Vivian was so traumatized she reportedly never got on a boat again.
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Then there was Howard Ulrich and his 7-year-old son on the Edrie. Howard saw the "explosion" of water at the head of the bay. He realized he couldn't get his anchor up in time, so he let out all the chain and prayed. His boat rode the wave like a cork. He described the crest as a "straight wall of water" at least 100 feet high by the time it reached him. He survived, but the third boat, the Sunmore, wasn't so lucky. It tried to run for the exit and was swallowed by the surf.
Why Lituya Bay is a Tsunami Trap
You might wonder why this doesn't happen in California or Florida. It’s all about the "perfect storm" of geography. Lituya Bay is a fjord. It’s deep, narrow, and surrounded by incredibly steep mountains that are sitting right on a major fault line.
- The Shape: The "T" shape of the bay acts like a funnel.
- The Landslide: This wasn't a "seismic tsunami" caused by the seafloor moving (like the 2004 Indian Ocean disaster). This was a "megatsunami" caused by a massive rockfall.
- The Depth: The water is deep enough to hold a massive amount of energy but shallow enough near the edges to force that water upward.
Actually, 1958 wasn't the first time this happened. Geologists have found evidence of at least four other massive waves in Lituya Bay dating back to the 1850s. The bay is basically a repeating record-breaker.
Megatsunami vs. Regular Tsunami: There’s a Difference
We usually use the word "tsunami" for everything, but scientists get picky here. A regular tsunami is usually caused by an earthquake on the ocean floor that displaces the entire column of water. These waves can be small in height but have massive wavelengths, traveling thousands of miles across the Pacific.
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A megatsunami, like the one in 1958, is different. It’s a localized "splash wave." It starts out incredibly tall—much taller than a regular tsunami—but it loses its energy much faster. If you were 100 miles away from Lituya Bay in 1958, you wouldn't have felt much of a wave at all. But if you were inside that bay? You were facing the largest wave ever recorded in human history.
What This Means for Us Today
So, should you be worried about a 1,700-foot wave hitting your beach house? Probably not, unless you live in a fjord in Alaska or Greenland. But there is a real-world takeaway here.
Climate change is causing glaciers to melt and permafrost to thaw. This makes mountainsides in places like Alaska, Norway, and British Columbia much more unstable. Scientists are now keeping a very close eye on places like Barry Arm in Alaska, where a slow-moving landslide could eventually drop into the water and trigger another megatsunami.
Next Steps and Insights:
If you’re ever traveling in coastal areas with steep terrain or fjords, it pays to be "tsunami literate." Here is what you actually need to know:
- Feel the Quake? Move. If you are near the coast and feel an earthquake that lasts more than 20 seconds, don't wait for a siren. Just get to high ground. In 1958, the survivors had about two to three minutes between the shaking and the wave.
- Watch the Water. If the ocean suddenly recedes or looks like it’s boiling, that’s your cue to leave.
- The "First Wave" Myth. The first wave is rarely the biggest. In Lituya Bay, the water "sloshed" back and forth for over 20 minutes with 20-foot "echo" waves.
- Check the Maps. If you live in a coastal zone, look up your local tsunami inundation maps. Emergency management offices provide these for free, and they show exactly how far inland a wave is expected to go.
Nature is powerful, sure. But the 1958 Lituya Bay event proves that even against a 1,700-foot wall of water, quick thinking and a bit of luck can mean the difference between life and death.