A recent landslide in Alaska’s Tracy Arm fjord triggered a powerful tsunami, sparking concerns about the increasing risk of such events due to glacier retreat caused by climate change.
The incident, described as “historic” by scientist Dennis Staley from the US Geological Survey, occurred on August 10, 2025, in a narrow 30-mile fjord with sheer walls looming thousands of feet above the water. Staley noted, “I feel like we dodged a bullet,” given that no one was hurt, despite the massive wave.
The landslide, estimated to involve up to 100 million cubic meters of rock, sent a wave of ocean water an incredible 1,400 feet up the opposite side of the fjord. This will likely make it one of the largest such waves ever recorded.
A tsunami estimated at up to 100 feet tall barreled down the inlet, stripping forest and brush from either shore. Thirty miles away, the wave was still 15 feet high, coming within inches of a tent where Sasha Calvey and two other kayakers were camped.
Calvey and her companions were lucky to have been spared, as they had to be rescued, ending their 78-day expedition from Washington state. “If the tsunami had occurred only three hours earlier, when the tide level was 10 feet higher, they may not have survived,” Staley said.
Jeffrey and Christine Smith, who had planned to anchor their 65-foot tour boat in Tracy Arm, narrowly escaped the disaster. Instead, they anchored about 45 miles away due to rainy weather and witnessed a 10-foot rise in water along the shore near their anchorage. “We’ve been feeling a little mortal,” Christine Smith said after learning how narrowly they missed the slide.
Some geologists worry that luck may be running out, as landslides near retreating glaciers appear to be increasing in Alaska and elsewhere.
One possible cause is that glacial ice, which can be hundreds of feet thick, may help support mountain walls above them. Scientists debate whether rapid glacial retreat may “de-buttress” mountainsides by removing supportive ice that has been in place for centuries.
Climate change is also thawing high-elevation permafrost around the world, which can cause instability deep within steep slopes. Staley emphasizes that it’s too early to say what led to the Tracy Arm slide, stating, “We have to be careful. We can’t say with any real certainty what triggered this event”.
This incident is not an isolated event. In 2015, a landslide near a receding glacier in Taan fjord in southeast Alaska sent water 630 feet up a nearby slope. A 2024 landslide near the Surprise glacier in Prince William Sound caused a small tsunami.
Additionally, a large landslide alongside the receding Pedersen glacier in Kenai Fjords national park triggered a wave estimated at 60-180 feet.
Scientists are also monitoring a recently discovered weak slope above the receding Portage glacier and a 3,000-foot unstable slope in the Barry Arm inlet, both of which could potentially trigger devastating tsunamis.
Researchers hope to improve understanding of the ties among landslides, glaciers, and climate change by installing high-tech equipment to track precipitation, slope movement, and other conditions on the mountain.
Michael West, the state seismologist, notes that review of seismic monitoring sites shows a seismic “popping” was occurring at the Tracy Arm site for roughly 24 hours before the slide, with hundreds of small signals detectable 100 miles away. “Not every landslide does this,” West says, expressing hope to research this phenomenon to better understand possible warning signals.