Permafrost beneath Arctic roads is warming and becoming less stable, creating growing risks for northern infrastructure. Yet predicting how frozen ground will evolve remains difficult because subsurface conditions vary sharply over short distances, observations are sparse, and conventional process-based models are not easy to update as new field data arrive. In a new study, Gou et al. [2026] address that challenge at an embankment road in Utqiaġvik, Alaska, using fiber-optic temperature measurements collected along a 100-meter transect to track how shallow ground conditions change through time. Rather than treating monitoring and modeling as separate tasks, the authors link them in a framework designed to evolve with the physical system itself.
What stands out here is not simply the use of machine learning, but the way the authors build a physics-informed digital twin for permafrost under infrastructure. Their framework embeds a neural network within a heat-transfer solver, so the governing physics remain central while the model can still update uncertain soil properties as new observations arrive. This study moves beyond black-box prediction toward an interpretable, updateable system that can reconstruct subsurface temperature fields, infer thermodynamic properties such as unfrozen water content and thermal conductivity, and then test those inferences against independent DAS data, borehole temperatures, and laboratory measurements. This makes the work more than a site-specific modeling exercise; it offers a credible pathway toward near-real-time permafrost forecasting and infrastructure monitoring in a rapidly warming Arctic.
Citation: Gou, L., Xiao, M., Zhu, T., Martin, E. R., Wang, Z., Rocha dos Santos, G., et al. (2026). Physics-informed digital twin for predicting permafrost thermodynamic characteristics under an embankment road in Utqiaġvik, Alaska. Journal of Geophysical Research: Earth Surface, 131, e2025JF008787. https://doi.org/10.1029/2025JF008787
—Xiang Huang, Associate Editor, JGR: Earth Surface
A wonderful new paper on the huge Tracy Arm landslide and tsunami will have profound but challenging implications for the management of risk in an age of increased tourism and rapid climate change.
The journal Science has published an excellent new paper (Shugar et al. 2026) that examines the extraordinary 10 August 2025 landslide and tsunami at Tracy Arm fjord in Alaska. The paper is open access, so you can read it for yourself (it is very accessible), and there has been a plethora of media coverage (quite rightly).
I wrote about this event at the time and in the aftermath, but Shugar et al. (2026) is the authorative source. There is little for me to add to the science, but AGU Eos has a really excellent write up and explainer that I thoroughly recommend.
That large landslides occur in fjords is not a surprise, and that they can generate enormous displacement waves is also not news. We know that landslide occurrence in these environments in general is increasing, and specifically so in Alaska. However, this paper is the most comprehensive and systematic analysis of such an event, and it has shown the remarkable threat that these events can generate. The tsunami created by this landslide had a 481 metre run-up; it is remarkable that there were no fatalities. If a large cruise ship had been in the area, with passengers being ferried ashore on small boats and exploring the shoreline, the consequences would have been catastrophic. It is unsurprising then that cruise companies are now amending their itineraries.
The USGS released the image below of the aftermath of the landslide and tsunami – scale is hard to understand in such images, but the crown of the landslide is over 1,000 metres above the level of the fjord, and the landslide had a subaerial volume of over 63 million cubic metres.
Shugar et al. (2026) has a brief section that examines the implications of this event, and of the understanding that it provides of the hazards posed by very large landslides in fjord settings. These are locations with extensive human activity – local communities, trade, fishing and tourism. There is some evidence that these landsldies are more likely to occur in the spring and summer months, when human occupation is higher. Our resilience to a tsunami wave that starts off being hundreds of metres high is low.
A case in point lies in Milford Sound in New Zealand, where (for example) an earthquake on the Alpine Fault has the potential to trigger a large landslide that could result in a major tsunami. Milford Sound is an extremely popular tourism location. Should such an event occur, and mass fatalities result, there is no doubt that the public inquiry would find that the societal risk was known and that it was probably unacceptable. However, to ban tourism, including cruise ships, in this area would carry heavy risks in its own right – it would profoundly impact the vital tourist economy of the area, on which many livelihoods depend. This is a substantial risk in its own right, and of course politics plays a major part too. Balancing these risks is a major challenge for any society.
Some hope is offered by the fact that this landslide showed substantial precursory seismic activity, which might represent a route to providing a warning for at least some of these rock slope failures. But research in this area is immature at the moment, and of course there will be no warning for a landslide triggered by a major earthquake.
So, the landslide at Tracy Arm fjord presents us with a host of major challenges, but it also represents a big step forward in our understanding of these events. Well done to Dan and his colleagues for another brilliant paper. I shall watch the debate with great interest.
Reference
Shugar et al. 2026. A 481-meter-high landslide-tsunami in a cruise ship–frequented Alaska fjord. Science, eaec3187. DOI:10.1126/science.aec3187
Elections chief says bid by ex-teacher to challenge senator with same name was filed ‘to confuse or mislead’ voters
There will still be one Dan Sullivan on the ballot, but election officials in Alaska determined a second man by the same name cannot run against him in the high-stakes Senate race.
A man named Dan Sullivan, or Daniel J Sullivan Jr, filed to run as a Republican against incumbent Alaska senator Dan S Sullivan, also a Republican. Republicans filed complaints against the other Dan Sullivan, saying the candidate had coordinated with a Democratic campaign to confuse voters.
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© Composite: Sullivan for Senate, CQ-Roll Call via Getty Images
© Composite: Sullivan for Senate, CQ-Roll Call via Getty Images
© Composite: Sullivan for Senate, CQ-Roll Call via Getty Images
In the early morning of 10 August 2025, a mountainside collapsed into the waters of Tracy Arm Fjord in southeastern Alaska.
This massive landslide produced a tsunami that reached 481 meters on the opposite side of the fjord—higher than all but the world’s 14 tallest buildings—and registered on seismic detectors around the globe. For days after the slope collapsed, the waters of the fjord churned with a standing wave known as a seiche.
This event was the second-largest tsunami ever recorded and the largest not linked to an earthquake. A new paper published in Science presented strong evidence that the Tracy Arm landslide was instead the result of the rapid retreat of South Sawyer Glacier, itself a consequence of global climate change.
“It’s like if you have a kid and they said they cleaned their room but really all they did was throw everything in the closet. As soon as you open that door, everything falls out.”
Nobody was harmed by the rockslide or tsunami, but cruise ships were scheduled to visit the fjord later that morning. If the collapse had happened just a few hours later, it could have been disastrous.
“While the [South Sawyer] Glacier is in the fjord, it’s supporting those valley walls, like the buttresses on a cathedral,” said Daniel Shugar, a geomorphologist at the University of Calgary who led the study. “As that glacier retreated over the last few decades, it retreated just past the spot that did fail. It’s like if you have a kid and they said they cleaned their room but really all they did was throw everything in the closet. As soon as you open that door, everything falls out.”
In other words, the glacier that carved the fjord in the first place was also holding its slopes in place, and the ice’s retreat under warming temperatures exposed rock that became vulnerable to crumbling. The proximate cause of the landslide might have been something else—as Shugar noted, rainfall is plentiful in that part of Alaska, which could have weakened the fjord’s walls further—but it might also have been a combination of small, individually insignificant factors. In any case, the removal of that glacial “closet door” was what made the collapse and tsunami possible.
“We know that steep slopes are very sensitive to the things that climate [change] is exacerbating, whether it’s losing permafrost, glacier retreating, or more water in the soil,” said glaciologist Leigh Stearns of the University of Pennsylvania, who was not involved with the Tracy Arm study. “Often, we think of glacier retreat as a long and continuous thing, but [it] can trigger sudden catastrophic events.”
The researchers shared their findings at a press briefing on Wednesday at the European Geosciences Union 2026 General Assembly.
The Tracy Arm tsunami, like the record-setting Lituya Bay 524-meter megatsunami in 1958, was so dramatic in part because it happened in a fjord. The steep sides of the relatively narrow channel concentrated the energy generated by the rockfall into water.
Unlike Lituya Bay, which resulted from an earthquake, Tracy Arm provided very little seismic warning before the slope collapsed, requiring forensic work to determine what caused it.
Shugar noted that South Sawyer Glacier had retreated by roughly 500 meters in the spring of 2025 alone, on top of the general trend of shrinking and thinning over the decades. And it’s not alone: Interferometric synthetic aperture radar (InSAR) images taken by satellites indicate that many slopes in Alaska and beyond are in motion, pointing to potential future danger.
“Not every single one, but it seems like a huge majority of [shifting slopes] are above the lower parts of thinning glaciers,” Shugar said. He described this phenomenon as “debuttressing,” as in losing the glacial buttress holding a slope up. He added, “I think in the next 5 years or so, we’ll probably have a much better understanding of just how and how quickly slopes respond to that debuttressing.”
“We were unbelievably lucky that the [tsunami] occurred with the timing that it did, and not 5 hours later.”
Most tsunamis are set in motion by earthquakes and travel across the open ocean, wreaking their destruction when they reach shallower water near coasts; the word “tsunami” means “harbor wave” in Japanese. The Tracy Arm tsunami joined the ranks of other landslide-driven tsunamis, like the ones in Taan Fiord (Alaska) and Dixon Fjord (Greenland), in being linked to human-driven climate change. Beyond the immediate impact of the waves, this category of hazard requires rethinking potential risks from abrupt catastrophes like debuttressing as well as slower effects such as sea level rise.
“The risk to any particular cruise ship [from a tsunami] on any particular day is very low,” Shugar said. “We were unbelievably lucky that the [tsunami] occurred with the timing that it did, and not 5 hours later. The risk certainly still could be increasing as we build new settlements, new mining camps, or new oil and gas infrastructure.”
Both Shugar and Stearns highlighted the importance of learning lessons from Tracy Arm and related events.
“Climate is a threat multiplier, and the research is really forcing us to look at these cascading hazards,” Stearns said. Tracy Arm “is one example of this: Small slow changes can trigger big events. Hopefully, we don’t need so many disasters to spur some change.”
—Matthew R. Francis (@BowlerHatScience.org), Science Writer
The formation of continental crust is a major unresolved question in Earth science. Volcanic arcs, such as the Aleutian Islands of Alaska, are thought to be an important source of new continental crust, but modern arc crust is usually more iron- and magnesium-rich than average continental crust. There are few places on Earth where scientists can directly observe the possible transition from mafic arc crust to more silica-rich, continent-like crust while an arc is still active. The Andreanof segment of the Aleutian Arc offers a rare opportunity to study this process because it is an active, relatively intact oceanic arc, without major disruption from back-arc spreading, and it contains several volcanic centers that may record different stages or styles of crustal evolution.
Mark et al. [2026] use seismic waves to image the crust beneath this arc segment. Their results show that this arc crust is still distinct from average continental crust, suggesting that additional chemical or physical changes are needed before arc crust becomes more continent-like. At the same time, localized zones of slower seismic velocity beneath the Atka and Tanaga volcanoes may indicate hotter and/or more silica-rich material in the lower crust. These findings provide an important in-place snapshot of early continental crust formation, while highlighting that the transformation from volcanic arc to continent is complex and still incomplete.
Citation: Mark, H. F., Lizarralde, D., Shillington, D. J., Cortés-Rivas, V., & Behn, M. D. (2026). Along-strike seismic structure of the Andreanof Aleutian Arc segment and implications for the formation of continental crust. Journal of Geophysical Research: Solid Earth, 131, e2025JB033339. https://doi.org/10.1029/2025JB033339
—Lindsay L. Worthington, Associate Editor, JGR: Solid Earth
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