On September 16, 2023, a remote fjord in East Greenland generated something scientists had never seen at a global scale, a slow, steady seismic pulse that lasted nine days and showed up on instruments around the world. The source was not a typical earthquake.<\/p>\n\n\n\n
It was a huge landslide that slammed into Dickson Fjord, launched a mega tsunami<\/a>, and then left the water rocking back and forth like a giant bathtub. Now, researchers have confirmed that \u201csloshing\u201d with direct satellite observations, turning an eerie geologic mystery into a climate-era warning signal.<\/p>\n\n\n\n The new confirmation comes from a June 3, 2025 paper in Nature Communications<\/a><\/em> titled \u201cObservations of the seiche that shook the world.\u201d The team used measurements from the Surface Water and Ocean Topography mission<\/a>, known as SWOT, to directly observe the water surface patterns consistent with a standing wave, also called a seiche<\/a>, inside the fjord.<\/p>\n\n\n\n The chain of events began when more than 25 million cubic yards of rock and ice broke loose and plunged into Dickson Fjord. Reports based on field and satellite evidence describe an initial tsunami reaching roughly 650 feet near the impact area. Even after that first violent surge, the fjord did not settle. The water continued to swing from wall to wall, repeatedly loading the seafloor <\/a>and generating a very long period seismic signal at about 10.88 millihertz, which corresponds to a rhythm of about 92 seconds.<\/p>\n\n\n\n That \u201cheartbeat\u201d quality is what made the event so confusing at first. Earthquakes usually produce a burst of shaking that fades quickly, not a clean pulse that stays coherent for more than a week. In this case, the signal weakened slowly over nine days, and then a similar signal returned around October 11, 2023 after a second tsunami producing landslide in the same fjord.<\/p>\n\n\n\n Before this latest work, multiple research groups had strong reasons to suspect a seiche was responsible, but they were relying on modeling and on what seismic<\/a> waves implied about the force direction. The new study adds the missing piece, direct water surface observations inside the fjord from SWOT\u2019s wide swath measurements.<\/p>\n\n\n\n That is a big deal because fjords are notoriously hard places to monitor. They are narrow, steep, remote, and often covered by ice for much of the year. Traditional instruments can be sparse or vulnerable. SWOT helps close that gap by mapping a broad swath of water surface height rather than just a thin track beneath a satellite. NASA<\/a> describes SWOT as a mission designed to survey Earth\u2019s surface water and improve understanding of climate-related questions, following its December 2022 launch<\/a>.<\/p>\n\n\n\n Using SWOT data alongside seismic records, the Nature Communications<\/em> authors estimated the initial amplitude of the seiche at about 7.9 meters, after ruling out other processes like tides and wind driven circulation as explanations for the observed cross fjord slopes.<\/p>\n\n\n\n It is tempting to treat this story as an exotic Arctic oddity. But the ingredients are not unique. As glaciers thin and retreat, they can stop acting as a stabilizing brace for steep slopes. That raises the odds of large rock and ice failures into confined waters, which is exactly the recipe for dangerous local tsunamis. The Science paper<\/a> on the Dickson Fjord event frames these tsunamigenic landslides as part of a growing hazard picture in polar regions as climate conditions shift.<\/p>\n\n\n\n Greenland has already seen what that can mean for people. In Karrat Fjord<\/a> on June 17, 2017<\/a>, a landslide triggered a tsunami that killed four people and destroyed or washed away multiple structures, including houses.<\/p>\n\n\n\n Dickson Fjord also sits near routes used by Arctic<\/a> cruises, an industry that has expanded as seasonal ice conditions change. When a single slope failure can generate both a towering wave and days of sustained oscillation, the safety question is no longer only about the initial impact. It is also about what the water keeps doing afterward, especially in narrow basins where resonance can trap energy.<\/p>\n\n\n\n Researchers are now combing seismic archives<\/a> for similar slow pulses that might have been missed. That work matters because the signal itself can become part of an early warning toolkit. A quake like this was not felt by people, but it was loud in the language of instruments. With satellites like SWOT adding direct surface measurements, scientists can better distinguish between \u201cnormal\u201d ocean motion and rare, high consequence events.<\/p>\n\n\n\nRead More: Goodbye to total consensus: Brazil proposes moving forward with climate action without waiting for agreement from all 195 UN countries<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
The moment a mountain hit the water<\/h2>\n\n\n\n
Read More: The ice that holds up half a meter of sea level begins to crack like a windshield<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
Why the satellite proof matters<\/h2>\n\n\n\n
Read More: Confirmed: First snowfall of the year begins covering solar panels \u2014 It’s producing a strange effect that will grow stronger<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
A climate risk that is easy to underestimate<\/h2>\n\n\n\n
Read More: While we eat crabs and lobsters at Christmas, science issues a warning that could change a tradition that dates back decades<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
Read More: Geologists discover a super-giant gold deposit in China with an estimated value of around $85,215,780<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
What to watch next<\/h2>\n\n\n\n
Read More: A study debunks decades of scientific research: underwater canyons are NOT created by rivers… and the explanation is brutal<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n