Just twelve hours later, however, the landscape underwent a catastrophic transformation. An immense section of the adjacent mountain suddenly gave way, plunging millions of tons of rock directly into the fjord. The catastrophic impact triggered the second-highest tsunami ever recorded in human history.
Researchers studying earthquakes and tsunamis at the Alaska Earthquake Center, including the Alaska state seismologist, have detailed the staggering scale of the disaster in a new scientific study published in the journal Science. According to the research, the landslide and subsequent wave forced water and debris an astonishing 1,580 feet (481 meters) up the opposing side of the fjord. To put that height into perspective, it reached higher than the top floor of the famed Taipei 101 skyscraper. The sheer force of the displaced water did not stop there, continuing its destructive path down Tracy Arm and stripping the fjord’s steep walls completely bare down to solid rock.
Fortunately, the cataclysm struck at just after five o’clock in the morning on a dreary, overcast day, and no cruise ships or private vessels happened to be nearby. In the immediate aftermath of the event, some commercial cruise lines adjusted their itineraries, choosing to avoid Tracy Arm altogether to mitigate future risk. Yet, scientists warn that the underlying conditions that precipitated this massive slope failure are far from unique to this specific corner of Alaska.
Landslides are a historically common occurrence throughout the rugged coastal mountains of Alaska, where rapid tectonic uplift and long-term glacial ice loss collide with heavy precipitation and the relentless erosive power of moving glaciers. However, geologists and seismologists have identified a concerning and curious pattern in recent years: multiple major landslides have taken place precisely at the terminus of retreating glaciers.
Although the exact mechanical physics are still poorly understood by the scientific community, these steep mountains appear to suffer a critical loss of structural stability as the supporting ice disappears. When a mountainside fails and violently impacts the water below, the sheer momentum of millions of tons of rock is instantly transferred into massive, destructive tsunami waves.
This exact phenomenon is increasingly playing out across the globe, stretching from the glacial fjords of Alaska to remote regions of Greenland and Norway, occasionally with tragic and deadly consequences. Across the Arctic and sub-Arctic, nations and local communities are struggling to come to terms with this expanding and poorly understood hazard. The available policy options are far from attractive: authorities can either attempt to permanently avoid vast, economically vital swaths of coastline, or communities can choose to live with an unpredictable and escalating risk.
Researchers argue that there is an obvious, life-saving role for advanced alert systems, but such measures can only be effective if scientists develop a much clearer understanding of where and when these catastrophic landslides are most likely to take place.
Signs that a landslide might be coming
The catastrophic failure at Tracy Arm serves as a powerful and sobering case study for how these events develop. The landslide occurred in August, a peak month when warm ocean waters and heavier seasonal precipitation favor both accelerated glacier retreat and ultimate slope failure.
In the weeks leading up to the disaster, the glacier situated directly below the unstable landslide area had experienced rapid calving, a process where massive chunks of ice break off and plunge into the water. In just the two months prior to the collapse, the glacier had retreated more than a third of a mile. Compounding this instability, heavy and persistent rainfall had been soaking the region. Rain naturally infiltrates fractures and fissures within the mountain rock, pushing the slopes closer to structural failure by dramatically increasing internal water pressure within these cracks.
Perhaps most provocative to researchers analyzing the aftermath are the thousands of small seismic tremors that emanated directly from the area of the slide in the days leading up to the final collapse of the mountainside.
Scientists believe that this specific convergence of warning signs would have been more than sufficient to issue progressive alerts to any ships operating in the vicinity, as well as to homes and businesses that could have been endangered by a tsunami, at least a full day prior to the failure—had a dedicated monitoring program been in place.
Escalating alert frameworks are already widely used across modern society for everything from national security threats and nuclear plant safety to winter avalanches and volcanic unrest. While such systems do not completely eliminate underlying risks, they successfully make it much easier for human populations to safely coexist with severe natural hazards.
For instance, although backcountry travelers are still occasionally caught and killed in winter avalanches, standardized warning and forecasting systems have played an essential role in making winter backcountry travel significantly safer for millions of people. The catastrophic collapse at Tracy Arm demonstrates clearly what could similarly be possible for tracking and warning against catastrophic landslides.
What an alert system could look like
Researchers believe that the hazardous combination of unusual weather and rapid glacier retreat observed in early August 2025 was likely sufficient to issue a broad advisory notifying the public that the environmental hazard was temporarily elevated across the general region. On a standard yellow-orange-red scale, this would have warranted a preliminary yellow alert.
In the crucial hours immediately preceding the landslide, the exponential increase in seismic events and the telltale transition into what seismologists classify as a seismic tremor—a continuous, low-frequency "hum" of seismic energy—provided enough data to communicate a highly time-sensitive warning for a specific, localized region.
These vital observations, which were recorded merely as a byproduct of regional earthquake monitoring networks, clearly warranted an "orange" alert signaling immediate concern. In hindsight, these gathered signs were arguably strong enough to recommend keeping all recreational and commercial boats and ships completely out of the fjord.
Recent scientific research over the past few years has successfully demonstrated that once a massive landslide has actually begun, it is entirely possible to detect, locate, and measure the event within a matter of a couple of minutes. During this brief window, seismic waves reverberating through the surrounding terrain can quickly indicate the rough physical size of the landslide and whether it occurred near an open body of water.
A dedicated monitoring program capable of rapidly communicating this data would then be able to issue a red alert, signaling an active, ongoing disaster.
The National Oceanic and Atmospheric Administration’s established tsunami warning program has spent decades fine-tuning the rapid dissemination of emergency messages. While a real-time warning system would have offered very little protective help for ships located in the immediate vicinity of Tracy Arm, it could have provided perhaps ten precious minutes of warning for residents, workers, and visitors who managed to ride out the harrowing tsunami further down the waterway.
Currently, there is no comprehensive landslide monitoring system operating at this critical scale anywhere in the United States. Constructing such a network will require close cooperation across various state and federal agencies, alongside significantly strengthened environmental monitoring and communication infrastructure. Even with a robust system in place, experts caution that it will never be entirely fail-proof.
Understanding risk, not removing it
Comprehensive alert systems cannot remove natural risks entirely from the environment, but they remain a vastly superior option compared to having no warning systems at all. Over time, these operational networks also help build public awareness as local communities, tour operators, and seasonal visitors grow accustomed to monitoring and respecting these geological hazards.
Many of the most visually stunning and alluring places on Earth inherently come with significant environmental hazards, and Arctic fjords certainly rank among them. The exact physical processes that create this severe hazard—including ongoing glacier retreat, precipitously steep terrain, and highly dynamic geology—are precisely the elements that make these landscapes so compelling to humanity in the first place. The unique mix of towering glaciers, ice-choked waters, and sheer mountain faces is what draws travelers from around the world, and people will undoubtedly continue to visit and experience them.
The central challenge facing authorities and scientists is not whether these magnificent places should be avoided altogether, but rather how to help people make more informed, safer decisions while visiting. Researchers emphasize that stronger geophysical and meteorological monitoring networks, combined with ongoing scientific research and improved communication channels, represent the vital first step toward achieving that goal.
On August 9, unsuspecting visitors passed leisurely through a remote wilderness landscape that was actively standing on the ultimate cusp of structural failure. A functional regional alert system might ultimately have given tour operators and individuals in the area the critical information they needed to make safer choices, avoiding being caught completely by surprise when the mountain gave way.
