The first detailed satellite view of a tsunami from space reveals a surprising new feature that could change how such waves are modeled and warned about.
Overview
A SWOT satellite, launched in 2022 by NASA and CNES (the French space agency), was built to map surface water height changes across the globe. While it spent years observing small currents, it unexpectedly captured a major tsunami in remarkable detail on July 29, 2025, when a magnitude 8.8 earthquake struck the Kuril-Kamchatka subduction zone off Russia’s southeastern coast. The tsunami raced across the Pacific, coinciding with SWOT’s overpass, enabling unprecedented measurements of the wave as it traveled.
This event was augmented by data from three DART buoys, which monitor deep-ocean tsunamis, allowing researchers to track the wave’s propagation and scattering more comprehensively than before. The combination of satellite and buoy data revealed that the tsunami’s behavior is more intricate than current models suggested.
Key Finding
Traditional tsunami models often treat large waves as non-dispersive, keeping a single coherent front as they move through the ocean. SWOT’s observations indicate a more complex pattern: the leading large wave is followed by smaller trailing waves, indicating dispersion and breakup of the tsunami as it travels. This challenges the long-held assumption and could lead to adjustments in predictive models and warning systems.
Angel Ruiz-Angulo, the study’s first author and a physical oceanographer at the University of Iceland, describes SWOT as “a new pair of glasses” for observing tsunamis. He notes that earlier satellites could only capture narrow slices of a tsunami, whereas SWOT can image a broad swath—about 120 kilometers wide—with high-resolution sea-surface data. This broader view improves the ability to observe how energy moves and disperses in real ocean conditions.
Implications
The enhanced observations promise to improve real-time tsunami detection and tracking, potentially extending warning times for coastal communities at risk. If future events align with SWOT’s capabilities, emergency managers could gain more accurate and timely information to guide evacuations and other protective actions.
Publication
The findings were reported in The Seismic Record, contributing to the ongoing conversation about tsunami forecasting and ocean dynamics.
