SWOT Satellite Records High-Resolution Pacific Tsunami Details

The Surface Water Ocean Topography (SWOT) satellite has captured the first high-resolution, spaceborne images of a giant tsunami in the Pacific Ocean, providing unprecedented detail about how these massive waves disperse and scatter across the ocean basin.

When a magnitude 8.8 earthquake struck the Kuril-Kamchatka subduction zone on July 29, 2025, it generated a Pacific-wide tsunami that the SWOT satellite happened to observe as it passed overhead. This rare opportunity allowed scientists to obtain detailed measurements of the tsunami’s sea surface height across a 75-mile-wide swath, revealing complex wave patterns that challenge existing forecasting models.

Unlike traditional instruments such as DART buoys—which provide time-series data at single points—SWOT maps ocean surface topography with high resolution across a wide area. This capability enables researchers to see how tsunami energy evolves in both space and time, showing a complicated, braided pattern of waves rather than a single neat crest racing across the basin.

According to Angel Ruiz-Angulo of the University of Iceland, lead author of the study published in The Seismic Record, “I think of SWOT data as a new pair of glasses. Before, with DARTs we could only see the tsunami at specific points in the vastness of the ocean. There have been other satellites before, but they only see a thin line across a tsunami in the best-case scenario. Now, with SWOT, we can capture a swath up to about 120 kilometers wide, with unprecedented high-resolution data of the sea surface.”

The findings suggest that the physics used to forecast tsunami hazards may need revision, particularly the assumption that large ocean-crossing waves travel as largely “non-dispersive” packets. Instead, the SWOT data shows significant dispersion and scattering of tsunami energy over hundreds of miles, which could improve understanding of how these events propagate and threaten coastal communities.

SWOT was launched in December 2022 as a joint mission between NASA and the French space agency Centre National d’Etudes Spatiales (CNES) to provide the first global survey of Earth’s surface water. Researchers had been analyzing SWOT data for over two years to study ocean processes like small eddies before capturing this historic tsunami event.

The July 29, 2025 earthquake in the Kuril-Kamchatka subduction zone was the sixth largest recorded globally since 1900. By combining SWOT’s wide-swath imagery with point measurements from DART buoys in the tsunami’s path, scientists are building a more comprehensive picture of the earthquake rupture and tsunami propagation.

This advancement in tsunami observation comes at a critical time for coastal disaster preparedness. More accurate models of tsunami dispersion and energy distribution could lead to improved early warning systems and better-informed evacuation plans for communities along the Pacific Rim and other vulnerable coastlines worldwide.