The story sounds like science fiction: a hidden wave the height of a skyscraper, ricocheting inside a remote Arctic fjord and making the planet hum like a bell. Yet that is what scientists now say happened in eastern Greenland, where a 650-foot wall of water formed after a mountainside collapsed into the sea and sent vibrations pulsing through the crust every 90 seconds. Only after months of forensic work with satellite images and seismic records did researchers connect the strange global tremor to a single catastrophic landslide.
What emerged is a rare, almost cinematic view of how ice loss, unstable rock and confined water can combine into a planetary-scale event. The mega-tsunami did not race across oceans to flood distant shores, but it did rattle instruments around the world and forced scientists to rethink how coastal hazards are monitored in a warming climate.
The day The Earth Shook Every 90 Seconds
Seismologists first noticed something was wrong when instruments on multiple continents began recording a perfectly regular signal that did not match any known earthquake pattern. Instead of a single jolt, Earth Shook Every 90 Seconds for Days, a drumbeat that persisted for more than a week and baffled the Scientists Finally Know who study such signals. The pattern was so regular that some initially wondered if it might be artificial, before the focus shifted to an unknown natural source.
Technical analyses of the waveforms showed an unusual mix of high and low frequencies that did not fit standard tectonic events. In detailed records, researchers identified a 200-sduration high frequency arrival, riding on top of a longer 60-s pulse that repeated as the event echoed. To the teams poring over the data, it looked less like a single rupture and more like something large sloshing back and forth in a confined basin, sending out a rhythmic thud each time it hit the walls.
A melting glacier, a collapsing mountain and a 650-foot wall of water
The breakthrough came when satellite specialists began combing through high resolution imagery of remote Arctic coastlines, looking for any sudden change that might match the timing of the seismic anomaly. In East Greenland, they found it: the fresh scar of a collapsed mountaintop above a narrow fjord, where a huge volume of rock had plunged into deep water. A new analysis described how a melting glacier destabilized the slope, priming it to fail and unleash a 650-foot surge that towered over the surrounding cliffs.
That initial wave, one of the highest recorded in modern times, did not have the open ocean to dissipate its energy. Instead, the water was trapped in a bendy, narrow fjord in Greenland, where the geometry turned it into a kind of natural wave tank. The subsequent mega-tsunami rebounded from one side to the other, its height gradually shrinking but its motion persisting long enough to keep shaking the crust. In that confined setting, the disaster was both localized and global: devastating within the fjord, yet felt as a subtle, repeating tremor across the planet.
Inside Dickson Fjord’s natural wave machine
Once the location was pinned down, researchers reconstructed the sequence in Dickson Fjord using multiple satellite platforms and numerical models. Imagery showed that Greenland‘s eastern edge, usually quiet, suddenly lit up in the data when a massive rockfall hit the water and set the fjord in motion. One account described how Mountain material cascading into Dickson Fjord displaced so much water that the surface rose into a crest reaching about 650 feet high, then began its relentless back and forth.
From there, the wave behaved less like a single tsunami and more like a standing oscillation, bouncing between the fjord’s head and its mouth. Reports describe how lasted for nine days, with the amplitude decaying from hundreds of feet to just a few inches while still coupling into the solid Earth. For scientists, Dickson Fjord effectively became a natural laboratory, revealing how a confined basin can trap energy and convert a single landslide into a long lived seismic source that repeats with metronomic regularity.
Imaging Earth-shaking waves from space and ground
What made this event uniquely revealing was the combination of satellite and seismic tools that captured it from different angles. Space based instruments tracked subtle changes in sea surface height and surface roughness, while ground based detectors recorded the vibrations as they radiated outward. In technical write ups, teams describe how In September, seismic detectors around the world picked up the repeating pulses while radar and altimetry satellites imaged the evolving wave field inside the fjord.
Orbiting platforms used by NASA and partner agencies were able to detect a 650-foot disturbance that shook the Earth for 9 days, demonstrating how Tsunamis can now be monitored from space as well as from shore based gauges. For me, the most striking aspect is how these complementary systems turned what would once have been an unexplained blip in the records into a fully reconstructed chain of cause and effect, from collapsing rock to planetary vibration.
From “Mysterious” signal to climate warning
Before the landslide was identified, some researchers informally dubbed the repeating tremor an unidentified seismic object, a label that captured both the mystery and the frustration. One scientist, Dr Stephen Hicks at UCL, recalled how the team wrestled with the anomaly until satellite sleuthing finally pointed to the fjord. Detailed coverage later described how the Mysterious 9 day seismic event was traced to a mega tsunami bouncing inside the fjord, turning a puzzling signal into a concrete physical process.
That detective story has sharpened the way scientists think about climate driven hazards in polar regions. A new study in Science framed the Greenland landslide as a direct consequence of warming, with retreating ice removing the buttress that once stabilized the mountain. Coverage of the work emphasized how Scientists are now treating such slopes as emerging risks and how, After roughly a year of analysis, the event has become a case study in the cascading impacts of climate change on coastal stability and global hazard monitoring.
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