In an astonishing development that unfolded in September 2023, scientists across the globe found themselves grappling with a perplexing seismic signal that persisted for an unprecedented nine days. This enigma drew the attention of an international collective of scientists, including notable seismologists Alice Gabriel and Carl Ebeling from UC San Diego’s Scripps Institution of Oceanography. It was not until a comprehensive study was published in the journal Science that light was shed on this obscure occurrence, revealing a catastrophic event in East Greenland: a significant mountaintop collapse, which led to a mega-tsunami towering approximately 200 meters (650 feet).
This extraordinary wave caused a series of reverberations throughout the nearby fjord, creating seismic waves that left many researchers at a loss. The phenomenon that emerged from this event is known as a “seiche,” characterized by rhythmic sloshing within the confines of the fjord. Thankfully, the incident resulted in no human casualties, but it did inflict considerable damage amounting to around $200,000 on the infrastructure of an unattended research facility located on Ella Island.
At the heart of this phenomenon lies the looming threat posed by climate change. The glacier at the base of the mountain had been weakened by rising global temperatures, destabilizing a staggering volume of rock and ice—over 25 million cubic meters—that ultimately plunged into the sea. This scenario serves as a grim reminder that as climate change exacerbates, the risk of large-scale, destructive landslides may increase significantly.
Kristian Svennevig, a leading geologist at the Geological Survey of Denmark and Greenland (GEUS), remarked on the collective confusion among scientists regarding the initial detection of the seismic signal. He stated, “When we set out on this scientific adventure, everybody was puzzled; no one had the faintest idea what caused this signal.” The collaborative effort spanned various fields, unveiling the complexities interconnected with climate change.
Initial seismic data captured in September was confounding for two key reasons. The waveforms recorded diverged significantly from the typical, chaotic signatures characteristic of earthquakes. Instead, they exhibited a slower oscillation, with peaks occurring at 92-second intervals—a period far beyond human perception. Furthermore, the sustained strength of the signal over days was strikingly different from more conventional seismic events, which tend to dissipate within a shorter timeframe.
In the scientific community, discussions flourished, linking the unusual signal to a massive landslide that transpired in a remote Greenland fjord on September 16, coinciding with the initial detection. To ascertain the connection, Svennevig led a multidisciplinary endeavor, amalgamating seismic recordings alongside satellite imaging and field studies. This approach brought together 68 scientists from 41 institutions, resulting in a detailed examination of the colossal landslide and its repercussions.
By utilizing advanced supercomputing capabilities, researchers modeled the tsunami’s formation and subsequent seiche dynamics. Gabriel pointed out the significant challenge posed by accurately simulating a tsunami that lasted for such an extensive period. Through high-resolution modeling, scientists successfully replicated both the wave’s height and behavior over time, enhancing their understanding of the wave’s trajectory as it interacted within the fjord.
This rigorous effort culminated in the revelation that the nine-day seismic signal correlated directly with the landslide-induced seiche in Greenland’s Dickson Fjord. As noted by Robert Anthony, a co-author of the study, the multidisciplinary collaboration underscored the necessity of integrating diverse data sources to draw conclusions from complex geological phenomena.
The ramifications of these findings stretch far beyond a simple academic curiosity. They illustrate the intricate cascade of dangers posed by climate change, especially in vulnerable polar regions. While no inhabited locales were affected during the landslide and resultant tsunami, the proximity of the fjord to popular cruise ship routes underscores the potential hazards that could arise as climate change escalates.
Past incidents, such as the 2017 Karrat Fjord landslide that flooded the village of Nuugaatsiaq—resulting in both destruction and loss of life—emphasize the urgency of monitoring these fragile ecosystems as climate-induced changes amplify. Gabriel suggested that increased awareness could drive future research efforts to identify similar seismic events in historical records, expanding the understanding of conditions that foster seismic phenomena like this enigmatic seiche.
The nine-day seismic mystery offers a startling perspective on the fragility of our planet’s geology, illustrating the profound effects of climate change on natural disasters. As researchers continue to unravel the complexities of these phenomena, it is clear that we must remain vigilant regarding environmental changes poised to reshape our understanding of Earth’s dynamics.
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