A recent study has highlighted how last year’s significant tsunami in an Alaskan fjord, frequented by cruise ships, serves as a critical reminder of the dangers associated with coastal rockslides and glacier retreats exacerbated by climate change.
Researchers observed the second-highest tsunami ever recorded globally, which struck the Tracy Arm fjord in southeast Alaska last August following a substantial rockslide near the glacier’s edge. This tsunami reached a height of 481 meters (1,578 feet), notably taller than the Eiffel Tower, which stands at 330 meters (1,082 feet).
The research, led by Dan Shugar, a geomorphologist at the University of Calgary, detailed that the event unfolded at 5:26 AM local time on August 10, 2025. A significant landslide, descending 1 kilometer vertically onto the South Sawyer glacier, triggered the massive wave in the narrow, 48-kilometer fjord.
Fortunately, there were no casualties during this early morning incident, but the area typically sees around three cruise ships per day, along with various other vessels operating within close proximity to the landslide site.
Just hours after the landslide, a sightseeing boat from Juneau and a National Geographic tour vessel, each with a capacity for over 100 passengers, were scheduled to enter the fjord. Additionally, two cruise ships carrying thousands of tourists had visited the region the previous day, with another ship set to arrive shortly after.
At the time, Dennis Staley of the US Geological Survey referred to the tsunami as “a historic event,” expressing relief in a comment to the Guardian, stating, “I feel like we dodged a bullet.”
The researchers emphasized that as fjord regions become increasingly popular with cruise ships and climate change raises the likelihood of similar incidents, the unanticipated nature of this event underscores the growing threat posed by landslides and tsunamis in coastal settings.
Notably, the tsunami was only slightly smaller than the tallest recorded tsunami in history, which occurred in Lituya Bay, Alaska, in 1958, reaching 530 meters (1,728 feet). The Tracy Arm event also instigated a 36-hour seiche, a phenomenon characterized by oscillating waves in a closed body of water.
The study revealed that the landslide produced long-period seismic waves comparable to those generated by a 5.4 magnitude earthquake.
Firsthand accounts documented in the study illustrated the tsunami’s extensive impact. A group of kayakers camping on Harbor Island, situated about 55 kilometers away, described how water surged past their tent, carrying off one of their kayaks and other equipment.
Another observer on a motor vessel in No Name Bay, approximately 50 kilometers from the landslide, reported witnessing a wave measuring between 2 to 2.5 meters cresting along the shoreline from the direction of Tracy Arm, followed by a second wave of about 1 meter, according to the researchers.
The findings indicated that tsunamis caused by landslides can result in significantly higher runups than those generated by earthquakes due to pronounced local variations in water depth and direct displacement of water caused by slope failures, particularly evident in confined bodies of water like fjords.
Researchers pointed out that the rapid retreat of glaciers driven by climate change was a contributing factor, stating, “Without this glacier retreat, the landslide would likely not have caused such a wave, as it would have collapsed entirely onto glacier ice or potentially not have occurred at all.”
In recent years, fjords with retreating tidewater glaciers have become increasingly popular for cruise tourism. The study noted a rise in annual cruise passenger numbers in Alaska from approximately 1 million in 2016 to 1.6 million in 2025.
Coupled with accelerating glacier retreat and the degradation of permafrost due to climate change, the potential for large-scale landslide-generated tsunamis is growing across the Arctic region.
As a result, researchers underscored the importance of understanding the scale and potential impact of such events. They advocated for enhanced risk mitigation strategies, including systematic monitoring of unstable slopes, more realistic tsunami modeling, and improved protection measures for local communities, tourists, and critical infrastructure.
Alaska has experienced several tsunamis in the past decade, including a significant landslide that produced an 18 to 55 meter wave in Kenai Fjords National Park in 2024, and another landslide near a receding glacier in Taan fjord that generated a 193-meter tsunami in 2015.
