New Satellite Data Confirms Greenland's Mega-Tsunami That Shook Earth For 9 Days

Last Updated:June 04, 2025, 08:54 IST

The wave, trapped between the steep fjord walls, sloshed back and forth every 90 seconds, creating powerful vibrations that were picked up by seismic sensors

The tsunami occurred after a huge chunk of rock and ice—about 25 million cubic metres—fell into the fjord in September 2023. (Image via NASA SWOT)

A powerful tsunami caused by a massive rockslide in Greenland in 2023 shook the Earth for nine and new satellite data has now confirmed the full extent of its impact. The rare event, which took place in a remote sea valley, sent waves bouncing back and forth within steep cliffs, creating seismic tremors detected thousands of miles away.

The international Surface Water and Ocean Topography (SWOT) satellite, operated by NASA and France’s CNES, detected the movement of water in Dickson Fjord, located on Greenland’s eastern coast.

The tsunami occurred after a huge chunk of rock and ice—about 25 million cubic metres—fell into the fjord in September 2023.

The wave, trapped between the steep fjord walls, sloshed back and forth every 90 seconds, creating powerful vibrations that were picked up by seismic sensors around the world.

The SWOT satellite passed over the area on 17 September 2023, just a day after the event. It recorded water levels that were up to 1.2 metres higher on one side of the fjord compared to the other—clear evidence of the wave’s continued motion.

“Seeing the shape of the wave — that’s something we could never do before SWOT," said Josh Willis, a sea level expert at NASA’s Jet Propulsion Laboratory. “SWOT happened to fly over at a time when the water had piled up pretty high against the north wall of the fjord."

The fjord itself is extremely deep and narrow, with depths of about 540 metres and surrounded by cliffs rising more than 1,800 metres high. Because of this tight space, the tsunami’s energy couldn’t spread out like it would in the open ocean, so the wave kept bouncing back and forth.

Experts say this event also proves how valuable the SWOT satellite is for tracking water movements and monitoring natural disasters.

“The KaRIn radar’s resolution was fine enough to make observations between the relatively narrow walls of the fjord," said Lee-Lueng Fu, the project scientist for SWOT. “The footprint of the conventional altimeters used to measure ocean height is too large to resolve such a small body of water."

According to SWOT scientists, this type of observation could help improve early warning systems and support disaster planning in the future.

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News world New Satellite Data Confirms Greenland's Mega-Tsunami That Shook Earth For 9 Days