On 29 July 2025, a powerful magnitude 8.8 earthquake struck the Kuril-Kamchatka subduction zone. It triggered a Pacific-wide tsunami. At the same time, NASA and the French space agency’s SWOT satellite passed over the area. It captured the first high-resolution space images of a major tsunami from a subduction zone. Unlike traditional DART buoys, which measure tsunami waves at scattered locations, SWOT recorded a wide 75-mile swath of the ocean surface. It revealed complex, braided wave patterns spreading across hundreds of miles. This was never seen before. The images challenge the old idea that large tsunamis travel as simple waves without spreading out. Angel Ruiz-Angulo, lead author from the University of Iceland, said SWOT is “a new pair of glasses” for tsunami study. Before, scientists had only isolated views from DART buoys. Now, SWOT offers broad, high-resolution data that shows how tsunami energy spreads. The satellite’s images showed dispersive wave behavior. This means tsunami waves break into parts as they travel, which was not expected for large tsunamis. Numerical models that include dispersion matched the satellite data well. This new understanding may improve tsunami prediction by explaining changes in wave strength and timing near coasts. SWOT worked alongside DART buoys during this event. Buoy data confirmed some wave heights but differed in other places. This led scientists to revise the earthquake’s rupture length from 300 to 400 kilometres. Co-author Diego Melgar said tsunami data are key to understanding earthquake slip and improve seismic analysis. The Kuril-Kamchatka margin has caused big tsunamis before, including a deadly magnitude 9 earthquake in 1952. That event helped start the Pacific tsunami warning system. In 2025, basin-wide alerts went out as the tsunami spread. Scientists hope satellites like SWOT will soon help with real-time tsunami monitoring. Ruiz-Angulo is optimistic future satellite data will be a regular tool for predicting tsunamis more accurately.