The escalating global temperatures are actively contributing to the widespread recession of glaciers. This phenomenon is observable across the planet.
The diminution of glacial bodies is not invariably a placid occurrence; it can profoundly reshape terrestrial topography. Our sophisticated network of orbital observation platforms serves as a testament to these transformations.
In the year 2025, the receding South Sawyer Glacier, situated within Alaska’s Tracy Arm—a remarkable inlet proximate to Juneau—precipitated a substantial terrestrial collapse.
As the ejected material from this geological event impacted the aqueous expanse, it instigated a colossal megatsunami that propagated down the fjord and ultimately into the open ocean.
During its devastating journey, the wave attained a monumental crest of 481 meters (1,578 feet), marking it as the second-highest tsunami ever documented by humankind.
A comprehensive analysis was conducted by researchers, utilizing a confluence of satellite imagery, aerial photography, and terrestrial data to meticulously reconstruct the sequence of events.
“The conspicuous landslide scar adorning the northern flank of the fjord is remarkable, as is the distinct ‘bathtub’ ring encircling the inlet, signifying the zones where the forest canopy was obliterated by the tsunami’s force,” Shugar commented in a press release.
These glacial masses themselves have been instrumental in sculpting the fjords. Glaciers function as immense, glacially paced waterways of ice; much like fluvial systems have excavated grand geological formations such as the Grand Canyon, glaciers have similarly shaped the iconic Alaskan fjords.
Inlets like Tracy Arm possess the characteristic of restricting tsunami propagation and energy dissipation. Instead, the immense volume of water is channeled and amplified as it surges down the confines of the fjord, inundating the slopes in certain areas and decimating arboreal and vegetative cover.
Sawyer Island, located approximately 9 kilometers downstream within the fjord, was virtually denuded, with only a sparse scattering of trees remaining upright.
As elucidated by the researchers in their scholarly publication, tsunamis generated by landslides can achieve greater wave heights than those originating from seismic events, attributed to “more substantial, localized variations in submerged topography and the direct displacement of the water column by slope failure – effects most pronounced within confined aquatic environments such as fjords.”
Within their published work, the authors also underscored the escalating peril posed by these types of tsunami events.
“With an increasing volume of cruise ships navigating fjord regions and the ongoing impact of climate change rendering similar occurrences more probable, this unforeseen, narrowly averted incident serves to highlight the burgeoning risks associated with landslides and their attendant tsunamis in coastal environments,” the authors conveyed.
The repercussions of the tsunami within the fjord extended beyond the immediate incident. For upwards of 24 hours post-initial event, the water continued to exhibit oscillatory motion within the inlet, a phenomenon known as a seiche.
In combination with the landslide, the seiche generated seismic disturbances that registered the equivalent of a magnitude 5.4 earthquake on the Richter scale.
While no fatalities resulted from this particular tsunami, the potential for harm was significant. Several kayakers who were camping on an island at the fjord’s egress had their watercraft and equipment dislodged by the surging waters. A smaller vessel operating in Endicott Arm, a neighboring fjord to Tracy Arm, experienced severe currents and fluctuations in water levels.
As the popularity of Alaskan cruising escalates, the inherent risks associated with landslide-induced tsunamis are projected to intensify. Ironically, it is the very glaciers that are undergoing retreat that serve as a primary attraction for increased maritime traffic.
“Fjords characterized by receding tidewater glaciers are increasingly sought-after destinations for both large cruise liners and smaller craft throughout the Arctic and Subarctic regions, with a notable concentration in southeastern Alaska,” the researchers indicate.
“In recent years, the influx of cruise ship passengers in Alaska has seen a substantial rise, from an annual average of approximately 1,000,000 in 2016 to an estimated 1,600,000 in 2025.”
In their concluding remarks, the authors highlight that a “warming climate concurrently elevates the frequency of large-scale landslides within glaciated fjords…”
Furthermore, they posit that seismic waves generated by seiches resulting from these landslide-induced events could potentially offer insights into developing more effective early warning systems for such phenomena in the future.
“This presents a novel avenue for the near-real-time detection of hazardous fjord processes in geographical areas with limited tide-gauge instrumentation or satellite surveillance, thereby advocating for automated seismic searches for narrowband signals as an integral component of future early-warning frameworks,” they propose.
This discourse was originally disseminated by Universe Today. Access the original publication for further context.
