SWOT Satellite Captures Unprecedented Detail of 2025 Kamchatka Tsunami
The NASA/CNES Surface Water and Ocean Topography (SWOT) satellite obtained direct observations of the 2025 Kamchatka tsunami, which followed a magnitude 8.8 earthquake on July 29, 2025. The satellite's data, captured approximately 70 minutes after the tsunami's onset, has provided detailed insights into tsunami generation and propagation mechanisms, enhancing the understanding of these events near subduction zone trenches.
Event and Satellite Observation
On July 29, 2025, a magnitude 8.8 earthquake occurred near Russia's Kamchatka Peninsula in the North Pacific, initiating a tsunami. The SWOT satellite, operated by US and French space agencies, passed over the region approximately 70 minutes following the earthquake's onset. This enabled the satellite to acquire high-resolution, two-dimensional measurements of sea-surface height with centimeter-level precision. The study also incorporated data from 10 other satellites, primarily designed for climate research, which detected subtle tsunami signals.
Key Observations and Findings
The SWOT satellite captured the full wavefield of the tsunami, including short-wavelength wave trains. These observations provided data on the directions, curvature, and wavelengths of the tsunami waves.
Analysis of this data, led by Ignacio Sepúlveda from San Diego State University, confirmed the tsunami generated within approximately 10 kilometers of the subduction-zone trench. This represents the first high-resolution spaceborne evidence of tsunamigenesis, offering insights into near-trench source mechanisms.
Researchers detected not only the initial wave of the tsunami but also a distinct pattern of smaller, dispersive waves that trailed behind it. These short-wavelength, dispersive tsunami waves had been theoretically predicted in computer models and studies but were challenging to confirm in real-world observations.
The data indicated that different wave components travel at varying speeds, with longer waves progressing faster and shorter ones lagging. The study also demonstrated that the intensity of these trailing waves increases as earthquake movement extends closer to the trench, suggesting a correlation between these waves and the specific location and mechanism of tsunami generation near the trench. The findings were published in the journal Science.
Implications for Tsunami Science and Preparedness
The insights gained from SWOT data offer information not previously possible with land-based measurements or seafloor sensors alone, which are often limited by sparse coverage and signal attenuation.
SWOT's capability to perform wide-swath scans of the ocean, generating 2D maps of sea surface height, allows scientists to analyze the shape, direction, and spacing of tsunami waves with greater precision.
These findings are expected to enhance global tsunami assessment and forecasting models, improving the understanding of tsunami propagation and development. While satellites like SWOT are not used for direct real-time warnings as they do not continuously monitor locations, their data can refine tsunami models and strengthen hazard assessments when available.
Bjarke Nilsson, a PhD student at DTU Space and a co-author of the study, noted that processing this satellite data enables researchers to improve models, which could support tsunami warning systems in coastal regions.
This advancement assists coastal communities in preparing for seismic and tsunami hazards.