TL;DR
A large landslide in Alaska’s Tracy Arm fjord generated a nearly 500-meter-high tsunami. The event was caused by glacial retreat and seismic activity, but no injuries occurred. It highlights risks from climate-induced geological hazards.
On August 10, 2025, a massive landslide in Alaska’s Tracy Arm fjord triggered a tsunami that reached a height of 481 meters, narrowly avoiding casualties due to the early morning timing. The event was caused by glacial retreat and seismic activity, and it underscores the increasing geological risks linked to climate change.
The landslide involved at least 63.5 million cubic meters of rock detaching from a mountain above the fjord, falling into the deep waters at the South Sawyer Glacier terminus. The impact generated a wave initially 100 meters high, which surged across the fjord at over 70 meters per second, culminating in the 481-meter runup on the opposite shoreline. This makes it the second-highest tsunami ever recorded on Earth, according to researcher Aram Fathian of the University of Calgary.
Regional seismic sensors recorded microearthquakes starting as early as August 5, intensifying in frequency until the main failure on August 10. The collapse was preceded by glacial retreat exposing the slope’s base, weakening the rock’s stability. Satellite imagery confirmed significant glacial thinning—up to 130 meters—between 2013 and 2022—contributing to the slope’s instability. The seismic event produced waves with energy comparable to a magnitude 5.4 earthquake, and the resulting water oscillation persisted for over a day.
Why It Matters
This event highlights the growing danger of climate-induced geological hazards, especially in glacial regions. The potential for similar landslides and tsunamis poses risks to local communities and tourists, emphasizing the need for monitoring and hazard preparedness in vulnerable areas. Although no injuries occurred this time, a similar event during peak tourist hours could have caused significant loss of life and property.
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Background
Tracy Arm fjord is a popular tourist destination, with more than 20 boats, including cruise ships, navigating the area daily during the summer. Historically, landslide-generated tsunamis are rare but highly destructive; the 1958 Lituya Bay event reached 530 meters. The recent event is part of a broader pattern of glacial retreat in Alaska, driven by climate change, which destabilizes steep slopes and increases landslide risks.
“It was the second highest tsunami ever recorded on Earth, but until now, almost nobody heard about it because it was a near-miss event.”
— Aram Fathian, University of Calgary
“The retreat of glaciers has exposed the slopes and reduced the ice support, making landslides more likely in the future.”
— Fathian, on climate effects
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What Remains Unclear
It remains unclear whether similar events will increase in frequency or severity due to ongoing climate change. The precise future risk level for other fjord regions is still being assessed, and early warning systems are not yet established for these types of landslide tsunamis.
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What’s Next
Researchers and authorities will likely increase monitoring of glacial stability and seismic activity in the region. Further studies are expected to refine risk assessments and develop early warning protocols for similar hazards in Alaska and other glacial fjord areas. Local authorities may also review safety measures for tourists and vessels operating in these zones.
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Key Questions
Could this happen again in Tracy Arm?
Yes, ongoing glacial retreat and seismic activity suggest the potential for future landslides and tsunamis, though the exact timing and magnitude are uncertain.
Was anyone injured or killed in the event?
No injuries or fatalities were reported, primarily because the event occurred early in the morning when few people were present.
How does climate change influence such landslides?
Warming temperatures cause glaciers to retreat and thin, removing ice support from slopes and increasing instability, which raises the likelihood of landslides in glacial regions.
What is being done to prevent future disasters?
Authorities are expected to enhance seismic and glacial monitoring, develop early warning systems, and review safety protocols for tourists and vessels operating in vulnerable fjord areas.
