Mega tsunamis in Greenland reached 650 feet height, had left scientists puzzled. The mystery is now solved

Scientists have decoded an unusual incident that unfolded in September 2023, when seismic stations across the world began to pick up a steady but unusual signal, repeating every 92 seconds.

This steady pulse lasted nine full days and returned for a brief period after a month. It was too faint for people to feel but strong enough to make its presence felt across Alaska to Australia – an unusual behaviour for a typical earthquake.

While scientists were baffled at first but the source was later traced to the remote Dickson Fjord in East Greenland – a narrow inlet that is bordered by 3,000-feet high cliffs.

A mega tsunami and the mystery behind it

New satellite images have now shown a fresh scar where a section of the mountain had vanished – indicating something something massive had struck the water and set the fjord in motion.

The answer lies in a colossal natural disaster that hit the area on September 16, 2023. On that day, over 25 million cubic yards of rock and ice – enough to fill 10,000 huge Olympic-sized swimming pools – collapsed into Dickson Fjord from the mountain side.

This set in motion a mega tsunami, with waves reaching heights of 650 feet. These waves surged along the two-mile corridor of the fjord, crashing against cliffs and bouncing back, creating a seiche – a prolonged, sloshing motion.

Unlike tsunamis, water in seiches go back and forth in an oscillating motion in an enclosed space repeatedly, sending low-frequency seismic energy for days through the earth's crust in a steady rhythm.

How scientists solved the puzzle

The credit of solving the puzzle goes to the Surface Water and Ocean Topography (SWOT) – a joint mission launched by NASA and French space agency in 2022.

Using this data, scientists observed water elevation changes that were subtle, with slopes of up to two metres, and hitting across the fjord. These waves were a match to the oscillation expected from seiches.

Scientists used machine learning to simulate wave behaviour over time to fill the gaps.

“It was exciting to be working on such a puzzling problem with an interdisciplinary and international team of scientists,” said Robert Anthony of the US Geological Survey.

“Ultimately, it took a plethora of geophysical observations and numerical modeling from researchers across many countries to put the puzzle together and get a complete picture of what had occurred,” he added.