A visualization based on data from the international SWOT satellite mission shows the unique contours of a tsunami that sloshed within the steep walls of a fjord in Greenland in September 2023. Triggered by a massive landslide, the tsunami generated a seismic rumble that reverberated around the world for nine days.

Short for Surface Water and Ocean Topography, SWOT collected water elevation measurements in the Dickson Fjord on Sept. 17, 2023, the day after the initial landslide and tsunami. The data was compared with measurements made under normal conditions a few weeks prior, on Aug. 6, 2023. Colors toward the lighter end of the scale indicate higher water levels, and darker colors indicate lower-than-normal levels. The data suggest that water levels at some points along the north side of the fjord were as much as 4 feet (1.2 meters) higher than on the south.

In a September 2024 paper in Science, researchers traced a seismic signal back to the tsunami, which began when more than 880 million cubic feet of rock and ice (25 million cubic meters) fell into the Dickson Fjord. Part of a network of channels on Greenland's eastern coast, the fjord is about 1,772 feet (540 meters) deep and 1.7 miles (2.7 kilometers) wide, with walls taller than 6,000 feet (1,830 meters).

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.

Launched in December 2022 from Vandenberg Space Force Base in central California, SWOT is now in its operations phase, collecting data that will be used for research and other purposes.

SWOT was jointly developed by NASA and the French space agency, CNES (Centre National d'Études Spatiales), with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. NASA's Jet Propulsion Laboratory, which is managed for the agency by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the KaRIn instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. CNES provided the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations. CSA provided the KaRIn high-power transmitter assembly.

To learn more about SWOT, visit: https://swot.jpl.nasa.gov/