Imagine a wall of water so tall it would swallow the One World Trade Center whole. It sounds like a scene from a low-budget disaster flick, right? But it actually happened. Back in 1958, a remote spot in Alaska witnessed the biggest tsunami in the world, a massive surge that reached a staggering 1,720 feet high. That is not a typo. We are talking about a vertical run-up that stripped trees and soil right off the bedrock of a mountain.
When most of us think of tsunamis, we picture the 2004 Indian Ocean tragedy or the 2011 disaster in Fukushima. Those were "teletsunamis"—events caused by massive undersea tectonic shifts that traveled across entire oceans. They were devastating because of their scale and the millions of people in their path. But Lituya Bay was different. It was a "megatsunami." These are localized, violent, and frankly, terrifyingly tall.
Why Lituya Bay Holds the Record
Lituya Bay is a T-shaped fjord located on the coast of the Alaska Panhandle. It’s beautiful, remote, and incredibly dangerous. The Fairweather Fault runs right through it. On the night of July 9, 1958, a magnitude 7.8 earthquake struck. This wasn't just a little rattling of the dishes. The force was enough to cause a massive landslide at the head of the bay.
Approximately 40 million cubic yards of rock—think of a giant chunk of mountain roughly 3,000 feet wide and 2,000 feet long—broke loose. It plummeted 3,000 feet straight into the deep water of Gilbert Inlet.
The impact was basically like dropping a brick into a bathtub, but the brick is a mountain and the bathtub is a narrow fjord. The displacement created a wave that slammed into the opposite shore with such force that it surged up the mountainside. Howard Ulrich, who was on a boat in the bay at the time and somehow survived, described it as the biggest thing he’d ever seen. He saw the wave move toward him, a literal wall of water.
The Science of "Run-up"
It's important to clarify what "1,720 feet" actually means because some people get confused and think the wave was a 1,700-foot-high crest moving across the open ocean. It wasn't. Scientists use the term run-up. This refers to the maximum height above sea level that the water reaches as it sweeps onto land.
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- Evidence: Geologists, including the legendary Don Miller from the U.S. Geological Survey (USGS), arrived shortly after the event. They found a "trimline." This is a clear boundary on the mountain where the old-growth forest had been completely erased. Below 1,720 feet, there was nothing but bare rock. Everything—the trees, the dirt, the moss—had been scoured away.
- Physics: Because Lituya Bay is narrow and confined, the energy of the water had nowhere to go but up. If this landslide had happened in the middle of the Pacific, the wave would have dissipated. In a fjord, it’s a death trap.
The Survivors: A Story You Won't Believe
Three fishing boats were in the bay that night. Honestly, it’s a miracle anyone lived to tell the story. Bill and Vivian Swanson were on the Badger. They were anchored when the earthquake hit. Bill looked toward the head of the bay and saw what he thought was a giant glacier rising into the air. It wasn't a glacier; it was the water.
The Badger was picked up by the wave and carried over the spit of land at the entrance of the bay. Bill later recalled looking down and seeing the tops of trees through the water as they rode the crest. Their boat eventually hit bottom and sank, but they managed to get into a skiff and were rescued.
The Edrie, captained by Howard Ulrich and his young son, also stayed afloat. Ulrich managed to head his boat into the wave. He described the experience as being like a cork in a storm. They survived. Sadly, the third boat, the Sunbeam, was lost with all hands.
Is This the Only One? Other Megatsunamis in History
While Lituya Bay is the biggest tsunami in the world in terms of recorded height, it isn't an isolated phenomenon. Geologists have found evidence of even larger events in the prehistoric past.
Vajont Dam, Italy (1963)
This wasn't a natural bay, but it was a man-made disaster. A massive landslide fell into the reservoir of the Vajont Dam. It created a wave that crested the dam and wiped out several villages below, killing around 2,000 people. The wave height was over 800 feet. It proved that you don't need a coastal fjord to have a megatsunami; you just need a lot of rock hitting a body of water at high speed.
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Mount St. Helens (1980)
When the volcano erupted, the entire north face of the mountain collapsed into Spirit Lake. This generated a megatsunami with a run-up of roughly 850 feet. It’s often overshadowed by the volcanic blast itself, but for a few minutes, Spirit Lake held a terrifying record.
The Molokai Collapse
If we go back further—like, way back—the Hawaiian Islands provide evidence of tsunamis that make Lituya Bay look like a ripple. Millions of years ago, a massive portion of the island of Molokai slumped into the ocean. Debris found high up on neighboring islands suggests a run-up height of over 2,000 feet.
Why We Should Still Care Today
You might think, "Okay, so a remote bay in Alaska had a big wave 70 years ago. So what?"
The reality is that climate change is making these events more likely in specific areas. As glaciers retreat, they leave behind unstable mountain slopes. In places like Greenland, Norway, and British Columbia, the risk of a "landslide-generated tsunami" is increasing.
In 2017, a landslide in Karrat Fjord, Greenland, triggered a tsunami that was 300 feet high. It hit the village of Nuugaatsiaq, destroying houses and killing four people. This wasn't ancient history. This was recently.
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Monitoring and Safety
Experts like Dr. Hermann Fritz from Georgia Tech have spent years modeling these waves to understand how they behave. The goal is to create better early warning systems for coastal communities. Unlike seismic tsunamis, which give you minutes or hours of warning, a landslide tsunami gives you seconds.
If you're ever in a narrow bay or a fjord and you feel a major earthquake, you don't wait for a siren. You get to high ground immediately. Don't look for your camera. Just move.
How to Prepare for Coastal Risks
Even if you aren't planning a trip to a remote Alaskan fjord, understanding the mechanics of the biggest tsunami in the world helps clarify the power of water. Most "normal" tsunamis are only a few feet or tens of feet high, but they carry immense momentum.
- Know your zone. Check local USGS or NOAA maps to see if your home or vacation spot is in a tsunami inundation zone.
- Learn the natural signs. A "drawback" (where the ocean recedes dramatically, exposing the seafloor) is a classic sign. So is a loud roar, often described as sounding like a freight train.
- The 20-minute rule. In many seismic events, you have a small window. If the ground shakes for more than 20 seconds and it's hard to stand up, the "Natural Warning" has been given.
Lituya Bay remains a haunting reminder of what happens when the earth moves and the water reacts. It's a freak occurrence of geography and physics that produced a height we hope never to see again. While the 1,720-foot mark is a terrifying statistic, the stories of the survivors remind us that even in the face of the planet's most violent outbursts, a bit of luck and quick thinking can go a long way.
Actionable Next Steps
To truly understand the scale of these events, look into the USGS interactive maps for coastal Alaska and the Pacific Northwest. They provide a clear visual of where fault lines meet deep water. Additionally, if you live in a coastal area, download the FEMA app; it provides real-time alerts for tsunami watches and warnings directly from the National Tsunami Warning Center. Knowledge of your specific elevation is your best defense. You can find this easily using your smartphone's compass or GPS app. If you are below 100 feet in a high-risk area, have a pre-planned "walk-away" route that leads to higher ground.