Imagine a wall of water so tall it doesn’t just flood a coastal town, but literally scrapes the trees off the side of a mountain 1,700 feet up. It sounds like a bad CGI movie. It’s not. In 1958, a massive rockfall triggered the biggest tsunami in history in a remote Alaskan inlet called Lituya Bay. We aren't talking about a typical ocean-crossing wave born from a deep-sea earthquake. This was a localized "megatsunami," a term scientists use when the scale of the displacement is just... well, stupidly large.
Most people think of the 2004 Indian Ocean disaster when they hear "tsunami." That was horrific and spanned continents. But Lituya Bay was different. It was a vertical monster.
The sheer physics of it are hard to wrap your head around. On July 9, 1958, an 8.3 magnitude earthquake on the Fairweather Fault sent 40 million cubic yards of rock—basically a whole mountainside—crashing into the deep waters of Gilbert Inlet. Think of it like dropping a giant brick into a bathtub, but the bathtub is a narrow fjord and the brick is a kilometer wide.
The result? A splash. But a splash that reached an astonishing height of 1,720 feet (524 meters).
Why Lituya Bay held the biggest tsunami in history
Lituya Bay is shaped like a giant "T." It's narrow, deep, and surrounded by steep, icy mountains. When that massive chunk of rock hit the water at the head of the bay, the energy had nowhere to go but up and out.
It wasn't a "wave" in the way you see at the beach. It was a massive surge of water that slammed into the opposite headland with enough force to strip every bit of vegetation, soil, and even the bedrock bare. If you go there today, you can still see the "trimline"—the distinct boundary where the old-growth forest ends and the younger, greener trees began growing back after being erased in seconds.
Don't confuse this with the "run-up" height. People often get mixed up here. The 1,720-foot figure is the height to which the water climbed the mountain, not the height of the wave as it moved across the bay. Still, as it traveled toward the mouth of the inlet, it remained a terrifying 100-foot-high wall of water.
Honestly, the survival stories are the craziest part.
There were three fishing boats in the bay that night. One boat, the Sunmore, was unfortunately near the deep end of the bay and vanished. No trace of the boat or the two people on board was ever found. But the other two? They somehow made it. Howard Ulrich and his 7-year-old son were on the Edrie. Ulrich saw the wave coming and realized he couldn't outrun it. He let out all his anchor chain, prayed, and watched as the boat was lifted up, up, and over the trees. He basically "surfed" the biggest tsunami in history and lived to tell the tale.
Then there was Bill and Vivian Swanson on the Badger. Their boat was carried over the spit of land at the entrance of the bay. Bill reported looking down and seeing the tops of trees beneath his hull before the boat crashed into the open ocean and sank. They escaped in a small skiff.
The Science of Megatsunamis vs. Tectonic Tsunamis
It’s important to distinguish between what happened in Alaska and what happened in Japan in 2011. Most tsunamis are caused by the seafloor dropping or rising during an earthquake. This moves the entire column of water above it. These waves are "only" maybe 30 to 100 feet high, but they carry trillions of tons of water across thousands of miles.
Lituya Bay was a "displacement" event.
Dr. Hermann Fritz, a leading expert in wave hydrodynamics, has spent years modeling this. Using scaled-down tanks, researchers proved that the landslide's impact was the sole driver. The speed of the rock hitting the water was so high that it created an "air cavity" behind it, pushing a massive volume of water ahead. This is why it didn't dissipate immediately.
- Landslide Tsunamis: High peak, short distance.
- Tectonic Tsunamis: Lower peak, global reach.
- Volcanic Tsunamis: Can be a mix of both (think Krakatoa).
Some geologists worry about the Canary Islands or even parts of Hawaii for this exact reason. If a volcanic flank collapses, we could see a repeat of the biggest tsunami in history on an even larger, more populated scale. It’s a "when," not an "if," though "when" might be 10,000 years from now.
Misconceptions about the 1,720-foot wave
You'll see clickbait videos claiming there was a wave taller than the Empire State Building moving across the ocean. That's just wrong. If you were standing in the middle of the North Pacific, you wouldn't have felt anything from the Lituya Bay event.
The "giant" part was the run-up on the mountain directly across from the landslide. By the time the water reached the mouth of the bay, five miles away, it had dropped significantly. Don't get me wrong—a 100-foot wave is still a skyscraper of water—but it wasn't 1,700 feet tall by then.
Also, people often ask: "Why didn't everyone know about this sooner?"
Well, in 1958, Alaska wasn't even a state yet. It was a territory. Communication was slow. It took days for the news to trickle out, and even longer for geologists like Don Miller to get on the ground and actually measure the damage. When Miller saw the stripped mountainside, he almost couldn't believe his own instruments. He had to cross-reference the damage with the known height of the trees to confirm the water had indeed reached that 1,720-foot mark.
What this means for you (Actionable Safety)
While you likely won't be in a remote Alaskan fjord during a landslide, tsunami safety is weirdly misunderstood. Most people think they should watch the water.
Never do that. If you feel an earthquake that lasts longer than 20 seconds near a coast, stop what you're doing.
- Look for the "drawback." Sometimes the ocean recedes dramatically before a tsunami hits, exposing seafloor you’ve never seen. This is not a time for photos; it’s a 5-minute warning.
- Move Inland and Up. You don't need to be 1,700 feet up like the Lituya Bay trimline, but you need height. Aim for at least 100 feet above sea level or two miles inland.
- Stay there. Tsunamis are a "train" of waves. The first one is rarely the biggest. People often die because they go back down to help others or see the damage after the first wave passes.
- Check Tsunami.gov. If you live on the West Coast or Hawaii, bookmark the NOAA Tsunami Warning Center. They track the deep-ocean buoys (DART system) that detect these things in real-time.
The biggest tsunami in history serves as a humbling reminder that the earth can reshape itself in minutes. Lituya Bay is quiet now, and the forest is slowly creeping back up toward that 1958 line. But the scars on the rock are still there, visible from the air, proving that nature’s power is way beyond our control.
Stay aware of your local geography. If you're vacationing in a place like Port Alberni, Hilo, or even parts of the Mediterranean, know your evacuation routes. Knowing where the high ground is can quite literally be the difference between a scary story and a tragedy.