Far below a steep Alaskan fjord, a strange seismic rhythm is pulsing through the rock, hinting at hidden forces inside a slope that some scientists fear could unleash a megatsunami. The signals are subtle and slow, but they are emerging from the same unstable mountainside that, if it fails in one violent collapse, could send a wall of water racing through coastal communities and across the North Pacific. As researchers decode this underground beat, they are also rethinking what recent disasters have already shown about how a warming climate can turn quiet valleys and remote fjords into global seismic events.
I see this new work as part of a broader shift in how scientists listen to the planet, using sensitive instruments and satellites to trace the full life cycle of giant waves, from the first crack in a slope to the last echo of energy that can make the Entire Earth hum for days. The mystery beneath Alaska’s Barry Arm is not just a local hazard story, it is a test of whether we can read the warning signs in time, and whether the next skyscraper-high wave will be caught in the data before it crashes into the shore.
The unstable Barry Arm and its hidden pulse
The immediate focus of concern is the Barry Arm fjord in Alaska, where a large, fractured slope towers above deep water and has been flagged as a potential source of a megatsunami. Researchers monitoring this unstable Barry slope have now detected a pattern of low-frequency seismic signals that do not match the sharp jolts of earthquakes or the rumble of an active landslide. Instead, the signals form a kind of background murmur, a repeating signature that hints at processes inside the mountain that are not yet visible at the surface, but that could shape how and when the slope finally fails, as described in new work on mysterious seismic signals.
From a hazard perspective, the location is unnerving because the fractured rock mass sits directly above deep water, a configuration that can turn a collapsing slope into a highly efficient wave generator. The potential collapse of the Barry slope has been modeled as capable of producing a megatsunami that would devastate nearby inlets and send damaging waves far beyond the fjord. The fact that scientists are now hearing a distinct seismic pattern beneath this specific site raises the stakes, because it suggests that the subsurface is active in ways that standard visual inspections or satellite images might miss, a point underscored by teams who have been tracking the unstable Barry Arm and its evolving hydraulic conditions.
What makes these seismic signals so unusual
What stands out in the Barry Arm data is not just that there is seismic noise, but that the pattern is both persistent and oddly detached from any obvious surface movement. The signals are not linked to actual motion of the slope, which means they are not simply the sound of rock blocks grinding past each other or small chunks falling into the fjord. Instead, they appear to be generated by processes inside or beneath the landslide mass, possibly involving water pressure, fluid flow, or slow deformation that does not yet rise to the level of a detectable slide. That disconnect between signal and visible motion is what makes the discovery so intriguing and so challenging to interpret.
Although the signals are not linked to actual movement of the slope, the researchers explain that they may still reveal how internal water and stress evolve over time and could influence when the slope becomes unstable. In other words, the seismic hum might be a proxy for changing hydraulic conditions, such as water seeping through fractures, building pressure, and subtly weakening the rock from within. If that interpretation holds, then the Barry Arm signals could become a kind of early-warning language, a way to track the countdown toward failure long before the first boulder breaks free, which is why the team emphasizes that these patterns could shape how scientists judge when the slope becomes unstable.
Climate stress and the rise of megatsunami-scale landslides
The Barry Arm story is unfolding against a backdrop of rapid climate change in high latitudes, where retreating glaciers and thawing permafrost are stripping away the natural buttresses that once held steep slopes in place. When ice that has supported a mountainside for centuries melts away, the rock above can suddenly find itself oversteepened and undercut, primed for collapse. That is not a theoretical risk, it is the pattern that has already played out in several recent disasters, where warming-driven destabilization turned quiet valleys into sources of giant waves and global seismic signals, a trend that gives the Barry Arm signals a sharper urgency.
One of the clearest examples came from Greenland, where a massive landslide into a fjord triggered a mega-tsunami and a distinctive seismic signature that rippled through monitoring networks. What happened in Greenland last September once again demonstrates the ongoing destabilization of large mountain slopes as ice retreats and temperatures climb, pushing these systems into uncharted waters and forcing scientists to rethink how quickly such hazards can develop. The Greenland event showed that a single slope failure can produce both a devastating local wave and a far-reaching seismic footprint, a combination that now frames how experts view the potential for a similar chain of events in Greenland-style settings like Barry Arm.
When the Entire Earth vibrated for nine days
The stakes of understanding these processes became impossible to ignore when scientists realized that a climate-triggered mega-tsunami had made the Entire Earth vibrate for nine days. In that case, a landslide-driven wave did not just devastate a remote coastline, it also set off a series of oscillations that rang through the planet’s seismic network for more than a week. The event was so energetic that it produced a global signature, a kind of planetary aftersound that forced researchers to connect the dots between a single slope failure and a worldwide seismic anomaly that had puzzled them for days.
That episode, described in detail in analyses of how the Entire Earth vibrated for nine days after a climate-triggered mega-tsunami, underscored how landslides and waves can masquerade as more traditional tectonic events in the data. Seismologists initially struggled to classify the signals, which did not fit the standard templates for earthquakes or volcanic tremors, until they traced them back to a landslide that had launched a skyscraper-scale wave. The realization that a single climate-linked landslide could produce a global seismic hum for more than a week has become a touchstone for current research, including the effort to interpret the new signals beneath Barry Arm, as highlighted in work on the Entire Earth vibrations.
The ‘Mega-tsunami’ mystery and satellite sleuthing
For months after those strange global vibrations, scientists were left with a mystery: what exactly had shaken the world for nine days, and where had the energy come from. The seismic records showed a persistent, low-frequency signal that did not match any known earthquake sequence, and there was no obvious volcanic eruption to blame. The breakthrough came when researchers turned to satellite imagery, combing through archives and new passes to look for signs of a giant wave or a fresh scar on a remote slope that could match the timing and scale of the seismic anomaly.
Eventually, satellite footage revealed the frightening cause of the earth-shaking vibrations, tying the nine-day signal to a mega-tsunami that had been hidden in plain sight in a sparsely monitored region. That work effectively solved the “Mega-tsunami” mystery, showing that a massive landslide and the waves it generated were responsible for the reverberations that had puzzled seismologists. The case has become a template for how to combine orbital data with ground-based sensors to decode unusual seismic patterns, a strategy that now informs how scientists approach the enigmatic signals beneath Barry Arm, as detailed in reconstructions of the Mega-tsunami source.
Skyscraper waves and the physics of seiches
Once the satellite images were in hand, scientists could finally visualize the waves that had shaken the planet, and what they saw were skyscraper-scale oscillations sloshing back and forth inside long, narrow fjords and lakes. These waves, known as seiches, behave a bit like water in a bathtub that has been jolted, except that the “bathtub” can be tens of kilometers long and hundreds of meters deep. When a landslide dumps a huge volume of rock into one end of such a basin, it can set the water rocking at its natural resonance frequency, producing waves that reflect and reinforce each other for days.
Researchers described how they had finally laid eyes on the seiches that were thought to have sent strange signals rumbling around the world, confirming that these oscillations were the missing link between the initial landslide and the prolonged seismic hum. The next step was to quantify the height and period of these skyscraper waves, using satellite altimetry and imagery to reconstruct their motion and match it to the seismic records. That work, which has been published in detail and showcased as the moment when scientists finally saw the skyscraper tsunami that shook Earth for nine days, now serves as a crucial reference for interpreting any future long-lasting seismic anomalies, including those that might emerge from sites like Barry Arm, as captured in analyses of the skyscraper tsunami.
Nature Communications and the new playbook for mega-tsunamis
The scientific backbone of this new understanding comes from a study in Nature Communications that pulled together seismic data, satellite imagery, and hydrodynamic modeling to reconstruct the full chain of events from landslide to global vibration. In that work, the authors presented the first direct satellite observations of the seiches that had been suspected but never before seen, and they used those observations to definitively link the oscillating water masses to the seismic anomalies recorded around the world. The result is a kind of playbook for diagnosing similar events, with clear signatures in both the imagery and the seismic waveforms that can be used to distinguish mega-tsunami-driven signals from other sources.
For hazard planners and monitoring agencies, the Nature Communications study is more than an academic milestone, it is a practical guide to what to look for when the instruments start to pick up something strange. The authors showed how specific patterns in the seismic data correspond to particular modes of basin oscillation, and how those modes can be inferred from the geometry of fjords and lakes seen from space. That framework is now being applied to other high-risk sites, including Barry Arm, where scientists are asking whether the newly detected seismic hum might be an early stage in the same kind of process that, in a previous case, produced skyscraper seiches and a nine-day global vibration, as laid out in the Nature Communications analysis of mega-tsunamis.
How scientists are listening for the next big wave
With these lessons in hand, researchers are now building more sophisticated listening posts around potential megatsunami zones, combining dense seismic arrays with GPS, radar, and satellite feeds. In places like Barry Arm, the goal is to capture not just the moment of failure, but the slow evolution of stress and fluid pressure that leads up to it, using the kind of low-frequency signals now emerging from beneath the slope as a key diagnostic. By tracking changes in the amplitude, frequency, and timing of these signals, scientists hope to distinguish between benign background noise and the kind of escalating activity that might herald an imminent collapse.
I see this as a shift from a reactive to a predictive mindset, where the focus is not only on recording disasters after they happen, but on decoding the subtle precursors that could buy communities precious time. The mysterious seismic signals beneath Barry Arm are a test case for this approach, forcing researchers to refine their models of how water, rock, and gravity interact inside a destabilizing slope. If they can successfully translate this underground rhythm into a reliable indicator of risk, it could transform how coastal authorities plan for rare but catastrophic waves, from Alaska to Greenland and beyond.
Living with low-probability, high-impact risk
For residents and policymakers, the hardest part of the Barry Arm story is that it sits squarely in the realm of low-probability, high-impact risk. A catastrophic collapse might not happen in our lifetimes, yet if it does, the consequences could be devastating for communities, infrastructure, and ecosystems across a wide swath of coastline. That tension makes it tempting to either downplay the danger or to overreact to every new data point, but the emerging science of seismic listening offers a more measured path, one that is grounded in continuous observation rather than speculation.
As I weigh the evidence from Barry Arm, Greenland, and the nine-day global vibration, I am struck by how quickly our understanding of these hazards has evolved once the right instruments were in place. A decade ago, a mysterious seismic hum might have remained an unsolved curiosity, but now it is a clue that can be cross-checked against satellite images, hydrodynamic models, and climate records. The challenge, and the opportunity, is to turn that growing knowledge into practical resilience, so that when the Earth’s hidden pulses hint at a coming wave, we are ready to listen and act before the water rises.
More from MorningOverview