Imagine you’re on a small fishing boat in a quiet, narrow Alaskan fjord. The sun has set, but the summer sky still holds that weird, late-night northern glow. Suddenly, the earth doesn't just shake—it groans. You look toward the back of the bay and see something that shouldn’t exist. A wall of water so high it’s literally scrubbing the trees off the mountainside hundreds of feet above your head.
That isn't a scene from a big-budget disaster movie. It actually happened.
On July 9, 1958, a remote spot called Lituya Bay became the site of the tallest tsunami in the world. We’re talking about a wave that reached a staggering 1,720 feet (524 meters). To put that in perspective, the Empire State Building is only 1,454 feet tall. This wave would have looked down on the New York skyline.
The Night the Mountain Fell
The whole thing started with a massive 7.8 magnitude earthquake along the Fairweather Fault. Alaska is no stranger to tremors, but this one was different. It triggered a colossal rockslide at the head of the bay.
Approximately 40 million cubic yards of rock and ice—imagine enough debris to fill a football stadium hundreds of times over—plunged 3,000 feet straight into the deep waters of Gilbert Inlet.
The impact was basically like dropping a brick into a bathtub, only the brick was a mountain and the bathtub was a narrow glacial fjord.
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Why Lituya Bay?
Lituya Bay is shaped like a giant "T." It’s narrow, deep, and surrounded by steep walls. When that mountain of rock hit the water, the displacement had nowhere to go but up.
It didn't just create a wave that traveled across the surface; it created a megatsunami. The water surged up the opposite slope with such incredible force that it stripped every single tree, every bit of soil, and every ounce of vegetation right off the bedrock.
Geologists call the line where the forest meets the bare rock a "trimline." In Lituya Bay, that trimline was measured at 1,720 feet above sea level.
Surviving the Unsurvivable
Most people think a wave that big would mean certain death for everyone nearby. Honestly, it’s a miracle anyone survived. There were three fishing boats in the bay that night.
One boat, the Sunmore, was unfortunately caught near the mouth of the bay and vanished. Another, the Badger, was carried over the spit at the entrance by the crest of the wave. The couple on board actually looked down and saw the tops of trees beneath them before their boat hit the rocks on the other side. They survived, but their boat was toast.
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Then there was Howard Ulrich and his seven-year-old son on the Edrie.
Ulrich saw the wall of water coming. He didn't have time to pull up his anchor, so he let out all the chain he had and prayed. The Edrie rose up the face of the wave, snapped the anchor chain like a piece of thread, and somehow rode the crest.
"It looked like just a big wall of water... like an atomic explosion," Ulrich later told researchers.
Common Misconceptions About the Tallest Tsunami
When people hear "tallest tsunami in the world," they often picture a 1,700-foot wave traveling across the open ocean. That’s not quite how it works.
- Run-up vs. Wave Height: The 1,720-foot figure refers to the run-up height—how high the water climbed the mountain. The actual wave traveling through the bay was likely closer to 100 or 200 feet high. Still terrifying, but not a half-kilometer-tall wall of moving water.
- Tsunami vs. Megatsunami: A "normal" tsunami is usually caused by the seafloor shifting during an earthquake. A megatsunami is caused by a massive impact, like a landslide or a meteorite. They are much taller at the start but lose energy way faster than regular tsunamis.
- The Deadliest vs. The Tallest: Surprisingly, only five people died in the Lituya Bay event. Compare that to the 2004 Indian Ocean tsunami, which was "only" about 100 feet tall but killed over 230,000 people. Location matters.
What Scientists Learned from Lituya Bay
Before 1958, many scientists didn't believe that a landslide could create such a massive wave. They thought only massive seafloor displacements could do that. Lituya Bay changed everything.
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It proved that "splash waves" from rockfalls could be the most vertically extreme events on the planet. This led to better monitoring of steep slopes near reservoirs and fjords. For instance, geologists now keep a very close eye on places like the Barry Arm in Alaska, where a retreating glacier has left a massive, unstable slope that could drop into the water at any time.
How to Stay Safe if You're in Tsunami Country
You've probably heard the standard advice, but it's worth repeating because tsunamis move faster than you can run.
- Heed the "Natural" Warnings: If the ground shakes hard enough that you can't stand, or if you see the ocean receding unexpectedly, don't wait for a siren. Get to high ground immediately.
- Vertical Evacuation: If you're in a flat coastal area and can't get to a hill, look for a reinforced concrete building. Go to the third floor or higher.
- Stay There: Tsunami waves aren't a one-and-done deal. Often, the second or third wave is the largest. Wait for an official "all clear" from local authorities.
Lituya Bay remains a haunting reminder of just how much power the earth holds. The scars on the mountainside are still visible today, a half-century later, showing where the world's tallest wave once touched the sky.
Practical Next Steps
If you live in or are visiting a coastal region, check the local tsunami evacuation maps. Most government websites (like NOAA in the U.S.) provide detailed PDFs showing exactly which streets are in the danger zone. Knowing your "blue line"—the point where you are safe from the water—takes five minutes to look up but could save your life in a real emergency.