A NASA satellite caught a giant tsunami doing something no one expected. The waves did not travel across the ocean as a simple, predictable swell. Instead, they scattered, spread, and interacted in complex patterns that scientists had never seen from space before.
A Rare View of a Pacific-Wide Tsunami
The tsunami was triggered by a magnitude 8.8 earthquake on July 29 off Russia's Kamchatka Peninsula. The quake struck in the Kuril-Kamchatka subduction zone, where one tectonic plate slides beneath another. It ranks as the sixth largest earthquake recorded anywhere in the world since 1900. The resulting waves raced across the entire Pacific Ocean.
A Satellite Built to Study Water
The satellite that captured this event is called Surface Water Ocean Topography, or SWOT. It launched in December 2022 as a joint mission between NASA and the French space agency Centre National d'Etudes Spatiales. Its main job is to create the first comprehensive global survey of Earth's surface water, tracking rivers, lakes, and ocean features. But on that day in late July, it happened to be in the perfect position to observe a major tsunami in motion.
Lead author Angel Ruiz-Angulo of the University of Iceland said the satellite provided a dramatically different perspective than anything scientists have had before. He compared SWOT data to a new pair of glasses. Previously, researchers could only see a tsunami at specific points in the vast ocean using DART buoys, which are designed to detect subtle changes in sea level. Other satellites could only capture a thin line across a tsunami in the best case. SWOT can capture a swath up to about 120 kilometers wide with high resolution data of the sea surface.
Ruiz-Angulo and co-author Charly de Marez had spent more than two years analyzing SWOT observations of ocean processes such as small eddies and currents. They never imagined they would be fortunate enough to capture a major tsunami. The research was published in The Seismic Record.
To study the event, researchers combined SWOT observations with measurements from DART buoys positioned throughout the Pacific. The satellite revealed that the tsunami displayed a far more complicated pattern than expected, with waves spreading, scattering, and interacting across vast stretches of the ocean. The findings also helped uncover a larger earthquake rupture than earlier models predicted.
This first high resolution, wide area view of a major tsunami generated by a subduction zone earthquake gives scientists a new tool. The unexpected wave behavior could help researchers improve tsunami forecasting and better understand potential risks to coastal communities.
