A powerful magnitude 8.8 earthquake struck off Russia's Kamchatka Peninsula on July 29, 2025, triggering a massive tsunami across the Pacific. NASA's SWOT satellite captured unprecedented high-resolution images of the waves, showing they were far more intricate and scattered than expected. This discovery challenges traditional models of tsunami behavior and could improve future predictions.
The July 29, 2025, earthquake in the Kuril-Kamchatka subduction zone registered a magnitude of 8.8, ranking as the sixth largest worldwide since 1900. It generated a tsunami that rippled across the Pacific Ocean, but instead of propagating as a single, stable wave, the event displayed surprising complexity.
The Surface Water Ocean Topography (SWOT) satellite, launched in December 2022 by NASA and France's Centre National d'Etudes Spatiales, fortuitously recorded the first high-resolution space-based track of this major subduction zone tsunami. Researchers, led by Angel Ruiz-Angulo from the University of Iceland, published their findings in The Seismic Record.
"I think of SWOT data as a new pair of glasses," Ruiz-Angulo said. "Before, with DARTs we could only see the tsunami at specific points in the vastness of the ocean... Now, with SWOT, we can capture a swath up to about 120 kilometers wide, with unprecedented high-resolution data of the sea surface."
By integrating SWOT observations with data from Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys, the team uncovered that the waves spread, interacted, and scattered in ways that contradicted the long-held view of large tsunamis as "non-dispersive." Simulations incorporating dispersion better matched the observations.
"The SWOT data for this event has challenged the idea of big tsunamis being non-dispersive," Ruiz-Angulo explained. The analysis also refined the earthquake's source: the rupture extended about 400 kilometers, longer than the previously estimated 300 kilometers, based on discrepancies in tsunami arrival times at DART gauges.
Co-author Diego Melgar, from the University of Oregon, emphasized the value of combining data types. "It is really important we mix as many types of data as possible," he noted, highlighting progress since the 2011 Tohoku earthquake.
This zone has a history of massive events, including a 1952 magnitude 9.0 quake that spurred the Pacific tsunami warning system, which alerted regions during the 2025 incident. Ruiz-Angulo hopes such satellite data could one day enhance real-time forecasting.
The findings suggest current models miss dispersive effects, potentially affecting coastal impact assessments.
