A catastrophic rockslide in a remote Greenland fjord in 2023 triggered a rare and powerful tsunami that defied expectations, not by its size alone, but by how long it endured. For relentless days, the wave ricocheted back and forth within the steep walls of Dickson Fjord, creating a rhythmic seismic pulse that echoed across the globe. Now, thanks to detailed satellite data from NASA and France’s CNES, scientists have unraveled how this ‘mega-tsunami’ unfolded and why it could be a warning sign of climate-linked instability in the Arctic.

The sudden impact triggered a mega‑tsunami, with waves reaching nearly 200 m (650 ft), that reverberated within the Fjord's steep walls for an astonishing nine days. Following the landslide on September 16, 2023, seismic stations worldwide recorded a subtle yet rhythmic vibration every 90 seconds—a monochromatic pulse that baffled experts for over a week.

How was this puzzle unraveled?

A breakthrough came from NASA and CNES’s SWOT (Surface Water and Ocean Topography) satellite. On September 17, SWOT’s Ka‑band Radar Interferometer (KaRIn) flew over Dickson Fjord, capturing detailed snapshots of water surface elevation. The images revealed tilting across the Fjord: the north side was elevated up to 1.2 meters (4 ft) higher than the south, confirming the oscillating waveform.

Josh Willis, a sea‑level specialist at NASA’s JPL, noted: “SWOT happened to fly over at a time when the water had piled up pretty high against the north wall of the fjord… Seeing the shape of the wave—that’s something we could never do before SWOT.”

Why It endured: The power of a Fjord

Dickson Fjord’s narrow, cavity-like geography—measuring about 1.7 miles (2.7 km) wide and 1,772 ft (540 m) deep, with walls soaring over 6,000 ft (1,830 m) acted like a natural resonance chamber. In this confined space, the tsunami couldn’t dissipate. Instead, the wave energy bounced back and forth, sustaining the seismic pulse for days.

“Far from the open ocean, in a confined space, the energy of the tsunami’s motion had limited opportunity to dissipate, so the wave moved back and forth about every 90 seconds for nine days. It caused tremors recorded on seismic instruments thousands of miles away,” the NASA article read.

Source: India TV News.