Imagine a wall of water so tall it doesn't just flood a coastal town—it reaches up and literally scrubs the trees off a mountain. It sounds like something from a big-budget disaster movie. Honestly, it sounds fake. But in 1958, nature did exactly that in a remote corner of Alaska. If you've ever wondered about the biggest tsunami ever recorded, you’re looking at the Lituya Bay megatsunami.
It wasn't your typical deep-sea earthquake ripple. This was a localized, violent surge that reached a staggering height of 1,720 feet. To put that in perspective, the Empire State Building stands at 1,454 feet. This wave would have cleared the tip of the antenna with room to spare.
Most people think of the 2004 Indian Ocean disaster when they hear the word tsunami. That was a tragedy on a global scale, sure. But in terms of sheer vertical height, Lituya Bay is the undisputed heavyweight champion. It’s a freak of geology and physics that scientists are still obsessed with today.
The Night the Mountain Fell into the Sea
July 9, 1958. It was a clear, calm evening in Lituya Bay, a T-shaped fjord on the Fairweather Fault. Three small fishing boats were anchored in the bay, their crews likely settling in for the night. Everything felt normal until 10:15 PM. That’s when a 7.8 magnitude earthquake rocked the region.
The ground didn't just shake; it tore.
This massive tectonic shift caused about 40 million cubic yards of rock and ice to break loose from a cliff at the head of the bay. Imagine a mass roughly the size of a small skyscraper plummeting 3,000 feet straight down into the narrow inlet of Gilbert Glacier. It wasn't a slide. It was a plunge.
When that much mass hits a confined body of water, physics takes over in a terrifying way. The displacement was instantaneous. The water had nowhere to go but up and out. This created the megatsunami, a term geologists use for waves caused by massive landslides rather than just seafloor displacement.
Why the Height is Often Misunderstood
You’ll see the number 1,720 feet (524 meters) cited everywhere. It’s important to get the nuance right here. The wave itself, as it traveled across the bay, wasn't necessarily a 1,700-foot-tall wall of moving water. That number represents the "run-up" height.
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As the surge slammed into the headland directly opposite the landslide, it climbed the mountain. It stripped every single tree, every bit of soil, and every piece of vegetation off the rock up to that specific elevation. When the water finally receded, there was a clear line—a "trimline"—between the old-growth forest and the bare, scoured rock.
Survival Stories That Defy Logic
There were survivors. Howard Ulrich and his seven-year-old son were on their boat, the Edrie, when the world ended. Ulrich later described a deafening crash and then seeing a wall of water that looked like a mountain itself.
He did the only thing he could: he slipped the anchor and tried to face the wave head-on. The Edrie was lifted up, carried over the trees on the shoreline, and somehow, miraculously, dropped back into the bay as the water pulled back. They lived.
Then there were Bill and Vivian Swanson on the Badger. Their experience was even more surreal. Their boat was carried over the spit at the entrance of the bay—riding the crest of the wave like a surfboard—at a height they estimated was 80 feet above the treetops. They eventually sank, but they managed to scramble into a skiff and were rescued later. Not everyone was so lucky. The third boat, the Sunmore, vanished. No trace of the vessel or its two passengers was ever found.
Comparing Lituya Bay to Modern Disasters
We need to talk about why this was so different from the 2011 Tohoku tsunami in Japan or the 2004 event in Indonesia.
- Source of Power: The 2004 tsunami was caused by a subduction zone earthquake. The entire seafloor rose, pushing a massive volume of water across an entire ocean.
- The "Splash" Factor: Lituya Bay was a "splash" wave. If you drop a brick in a bathtub, the splash can hit the ceiling even if the water in the tub is only six inches deep. That is essentially what happened in Alaska.
- The Reach: While the Lituya Bay wave was taller, it dissipated quickly once it hit the open ocean. The 2004 tsunami had less height but vastly more energy and a much longer wavelength, allowing it to kill hundreds of thousands of people thousands of miles away.
Basically, Lituya Bay was a localized monster. It was the tallest, but not the "biggest" in terms of total water volume or destructive footprint across a continent.
How Scientists Proved the 1,720-Foot Claim
For a long time, people were skeptical. How could water reach nearly 2,000 feet? It sounds like a fisherman’s tall tale. However, United States Geological Survey (USGS) scientist Don Miller was on the scene shortly after the event.
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He didn't need to see the wave; he saw the scars.
The trimline was undeniable. Miller documented the destroyed forest and the bare rock. In the decades since, computer modeling has caught up with his observations. Researchers at the Georgia Institute of Technology and other institutions have run fluid dynamics simulations that confirm a landslide of that volume, falling from that height into that specific shape of bay, would indeed produce a run-up of exactly that magnitude.
The geometry of Lituya Bay is a "perfect storm" for megatsunamis. It’s narrow, it’s deep, and it’s surrounded by unstable, glaciated mountains sitting right on a major fault line. In fact, smaller tsunamis were recorded there in 1853, 1874, and 1936. But 1958 was the big one.
The Risk of Future Megatsunamis
Could this happen again? Yes. And it probably will.
Geologists are currently keeping a very close eye on Barry Arm, another Alaskan fjord. A massive slow-moving landslide there is currently creeping toward the water. If it collapses all at once, it could generate a wave hundreds of feet high.
Climate change is making this worse. As glaciers melt and permafrost thaws, the "glue" holding these mountains together weakens. We are seeing more "rock-ice avalanches." In 2015, a similar event occurred in Taan Fiord, Alaska, generating a 633-foot wave. No one was there to see it, but the scars on the mountainside told the story.
What Most People Get Wrong About Tsunami Safety
When people read about the biggest tsunami ever recorded, they often walk away with the wrong idea about how to stay safe. They think they need to look for a 1,000-foot wave.
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In reality, a tsunami that is only three feet high can knock you off your feet and carry you away. A ten-foot wave can level a house. You don't need a megatsunami to have a mega-disaster.
The real danger isn't just the height; it's the debris. Tsunami water isn't "clean" like a surfing wave. It’s a slurry of crushed cars, shattered wood, glass, and boulders. It acts more like liquid concrete than water.
Essential Survival Steps
If you live in or are visiting a coastal area, forget the 1,700-foot outlier for a second and focus on these practicalities:
- Natural Warnings: If the ground shakes violently for more than 20 seconds, don't wait for a siren. Move inland.
- The Ocean's Retreat: If the water suddenly pulls back, exposing the seafloor or reefs that are usually submerged, the wave is minutes away. Run for high ground immediately.
- High Ground is Relative: You don't need to climb a 2,000-foot mountain. Usually, 100 feet above sea level is enough to survive the vast majority of tsunami events.
- Stay There: Tsunamis are a series of waves. Often, the second or third wave is larger than the first. People frequently die because they go back down to the beach to help others or see the damage after the first wave recedes.
Looking Ahead: Monitoring and Detection
We are much better at detecting these things now than we were in 1958. The DART (Deep-ocean Assessment and Reporting of Tsunamis) buoy system can detect pressure changes on the ocean floor and beam that data to satellites.
But for megatsunamis in narrow fjords? Those happen too fast for buoys to matter. For those, we rely on terrestrial GPS and satellite radar (InSAR) to watch mountainsides for movement.
The 1958 Lituya Bay event remains a stark reminder that our planet is geologically alive. It’s a place of sudden, violent shifts. While it’s unlikely you’ll ever face a 1,720-foot wall of water, understanding how these events work helps us respect the sheer power of the landscapes we inhabit.
Next time you’re looking at a map of a rugged coastline, look for those deep, narrow inlets. They are beautiful, yes, but they are also the cradles of the largest waves the world has ever seen.
To stay informed on current geological risks, you should regularly check the USGS Earthquake Hazards Program or the National Tsunami Warning Center. If you plan to hike or boat in "high-risk" areas like the Alaska coast or British Columbia, carry a satellite messenger with emergency alert capabilities, as cell service in these "megatsunami zones" is non-existent. Familiarize yourself with local "Tsunami Evacuation" signs; they aren't just there for decoration. Knowing the quickest route to 100 feet of elevation can literally be the difference between a survival story and a tragedy.