In an extraordinary event that captured the attention of scientists worldwide, seismic monitoring stations began detecting a peculiar rhythmic signal in September 2023. Every 90 seconds for a span of nine days, the Earth seemed to pulse gently but consistently, leaving experts both fascinated and perplexed. This phenomenon, which notably reappeared in October of the same year, originated from the remote Dickson Fjord in East Greenland. Interestingly, there were no indications of an earthquake, volcanic activity, or explosions to justify these tremors, raising numerous questions about their source.

Initially, some scientists theorized that the unusual seismic activity might have been the result of submarine volcanic eruptions or even covert military tests. However, as investigations unfolded, a team of researchers from the University of Oxford utilized cutting-edge satellite technology and machine learning to unravel the mystery behind these rhythmic pulses. Their findings not only pinpoint the cause of the seismic phenomenon but also shed light on the broader implications of climate change, particularly in sensitive and remote Arctic regions.

The rhythmic signals, which were subtle yet consistent—much weaker than typical earthquake vibrations—were recorded globally, indicating their widespread reach. Scientists quickly moved beyond initial theories of a tsunami, identifying the tremors instead as a seiche—a lesser-known yet powerful oscillation of water.

In the case of the Dickson Fjord, researchers established that the seismic pulses were generated by two massive rock and ice avalanches, which cascaded into the fjord and displaced substantial volumes of water. These events generated waves that reached heights of up to 7.9 meters. However, due to the fjord's narrow and enclosed structure, the waves could not escape and instead oscillated back and forth like water sloshing in a bathtub. This phenomenon, characterized by sustained oscillations, produced low-frequency seismic energy that was detectable across continents.

One of the pivotal tools in uncovering the cause of these pulses was NASA’s Surface Water and Ocean Topography (SWOT) satellite, which was launched in December 2022. Featuring a Ka-band Radar Interferometer (KaRIn), this satellite allowed scientists to conduct high-resolution scans of a 30-mile-wide area of the ocean surface—something that no prior satellite had accomplished. Utilizing data from the SWOT satellite, researchers mapped subtle changes in the fjord’s surface elevation following the avalanche events. They noted variations of up to two meters across the channel, indicative of standing wave motion.

To complement the satellite data, researchers also integrated crustal deformation data from sensors located thousands of kilometers away and analyzed weather patterns to rule out the influence of wind and tides. This comprehensive, multidisciplinary approach ultimately confirmed that the rhythmic seismic pulses were indeed a result of seiche-driven energy trapped within the fjord.

Perhaps the most alarming insight from this study is the connection to climate change. As temperatures in the Arctic continue to rise, the glaciers of Greenland are melting at an unprecedented rate. This not only destabilizes the surrounding slopes but also increases the frequency of catastrophic landslides. Lead researcher Thomas Monahan underscored the significance of the study, stating, “The findings highlight how geological events driven by climate change can have widespread seismic effects—often occurring quietly and without warning.”

This incident represents a transformative moment in the field of Earth observation. Professor Thomas Adcock, a co-author of the study, noted, “We are entering an era where advanced satellite data and modeling can help demystify natural phenomena that have, until now, eluded our understanding.” Interestingly, a Danish military vessel patrolling the fjord just three days after the initial pulses reported nothing unusual, emphasizing how even significant geological events can leave minimal traces unless monitored with sophisticated technology.