The 2025 Alaskan Tsunami That Measured 1578 Feet Tall

Last year in an Alaskan fjord, a surprise landslide triggered a tsunami 1578 feet tall. That’s not a typo…the wave was taller than all but 13 of the world’s tallest buildings.

In the early hours of August 10, 2025, an enormous landslide triggered a massive tsunami down the fjord. The tsunami was 1,578-feet-tall, or one-and-a-half times the height of the Eiffel Tower. Fortunately, no one was caught in the wave since it hit around 5:30 a.m. local time. If the tsunami hit later that day, about 20 cruise ships and numerous recreational boaters and kayakers could have been impacted by the giant wave.

In a study published today in the journal Science, researchers studied this “near miss” event, finding that the continued effects of climate change were likely the cause.

The mass of rock that set off the wave contained “a volume 24 times larger than that of the great pyramid of Giza”, with the initial wave moving at ~150mph. Professor Dan Shugar explains what happened on that morning and shows a simulation of what happened:

From this piece in the NY Times:

The Tracy Arm landslide was preceded by an unusually rapid retreat of the South Sawyer Glacier, leaving the rock slope that ultimately collapsed bare and unsupported. That same rearrangement of land elements is increasingly occurring throughout Alaskan fjords and around the world. As glaciers retreat and thawing permafrost lubricates slopes, these giant landslides may become more frequent.

Incredibly, this isn’t even the largest recorded tsunami; a 1958 earthquake with a magnitude of 7.8 to 8.3 triggered a rockslide that created a wave 1,719 feet tall in Lituya Bay. If you don’t want to waste a couple of hours, I’d suggest not clicking through to the megatsunami Wikipedia page.

See also When the Mediterranean Sea Dried Up.

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• tsunamis
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