Space views to seafloors: Satellite discovery marks defining moment in tsunami science
New research from the 2025 Kamchatka earthquake reveals hidden signals helping to improve seismic and tsunami hazard assessments.
When an earthquake strikes offshore, the first questions are urgent: Could the shaking generate a tsunami, where would it approach shore and what does it mean for people along the coast?
New research led by 麻豆传媒映画 assistant professor Ignacio Sep煤lveda offers a way to answer those questions. In collaboration with researchers in three nations, Sep煤lveda used satellite observations to capture tsunami details that are often difficult to measure with traditional tools.
, one of the world鈥檚 top peer-reviewed academic journals, published by the American Association for the Advancement of Science. It focuses on the July 29, 2025, magnitude 8.8 earthquake off Russia鈥檚 Kamchatka Peninsula. After the quake, the U.S.-French (SWOT) satellite passed over the region and recorded a distinct pattern of short-wavelength 鈥渄ispersive鈥� tsunami waves trailing behind the leading wave. Those trailing waves matter.
Researchers found they act like a fingerprint of earthquake slip occurring within a depth of 10 kilometers beneath ocean trench, a critical part of the seafloor where some of the most tsunami-generating movement can occur. That area is notoriously hard to measure using land-based seismic and geodetic instruments or even deep-ocean pressure sensors.
鈥淲e鈥檙e illuminating properties of earthquakes that advance our knowledge and clarify scientific questions for the community,鈥� said Sep煤lveda, who teaches coastal engineering in the . 鈥淭his helps us improve our understanding of earthquakes that rupture close to the trench and helps coastal communities better prepare for seismic and tsunami hazards they face.鈥�
The study highlights how advances in satellite technology, combined with international collaboration, are expanding what scientists can see in the moments after a major offshore earthquake and strengthening the scientific foundation for tsunami hazard assessment worldwide.
The Kamchatka earthquake generated a highly energetic tsunami that traveled across the Pacific. Runups exceeding 17 meters were reported in Severo-Kurilsk, Russia, and large waves were recorded along distant coastlines. Five nearby Deep-ocean Assessment and Reporting of Tsunamis, or DART, sensors captured the leading wave, with the closest measuring a crest-to-trough height of 1.32 meters.
While those instruments are essential for warning systems, they provide measurements at single points that are often spaced far apart. Shorter-wavelength signals can also weaken with depth, making it difficult to fully resolve what happened close to the trench.
SWOT adds a broader view. About 70 minutes after the earthquake, the satellite passed roughly 600 kilometers from the epicenter and imaged the tsunami in two dimensions. It captured not only the leading crest but also a sequence of trailing short-wavelength disturbances. Those wide-swath measurements reveal wave direction, curvature and wavelength, information not directly available from traditional one-dimensional satellite altimetry or sparse seafloor sensors alone.
Sensitivity analyses of earthquake slip indicate that tsunami generation occurred within 10 kilometers of the trench, an inference the researchers say cannot be resolved from land geodesy or deep-water pressure records alone.
鈥淭his discovery shows the importance of the U.S. and the world investing in satellite capacity measuring what is happening on our planet regarding geo-hazards,鈥� Sep煤lveda said. 鈥淭his satellite helps us understand tsunami and seismic hazards through a new lens, one that鈥檚 much clearer than before.鈥�
Sep煤lveda worked in collaboration with researchers from the Technical University of Denmark (DTU Space), the University of California San Diego鈥檚 Scripps Institution of Oceanography, and Instituto de Geograf铆a at Pontificia Universidad Cat贸lica de Valpara铆so in Chile. Their findings build on earlier observations. SWOT detected similar trailing waves after a May 19, 2023, tsunami near the Loyalty Islands in the South Pacific and following the May 2, 2025, magnitude 7.4 Drake Passage earthquake off the tip of Argentina.
Taken together, the events suggest dispersive tsunami signals may be more common than previously recognized. Their lack of presence in past records likely reflects technological limits to observe rather than rarity in nature.
For coastal communities, the implications are practical. Tsunamis often arrive as a series of waves, and later waves can still cause damage. By capturing those detailed wave patterns near the source, scientists can better understand how an earthquake ruptured and refine the models used to assess tsunami hazards.
Better observations lead to better modeling. And over time, the researchers say stronger models can support more informed planning and preparedness for communities exposed to tsunami risk. Since 2021, the 麻豆传媒映画 Coastal Engineering Lab has been training undergraduate and graduate students to investigate these extreme events and run models that evaluate how coastal communities are exposed to these hazards, helping build a more resilient world.
Sep煤lveda鈥檚 portion of the work was funded through the 麻豆传媒映画 Research Foundation Seed Grant Program.
