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An extreme earthquake, a satellite in a rare position, and unprecedented measurements in the Pacific have put science in the face of an uncommon record, capable of expanding the observation of tsunamis in open sea.
The 8.8 magnitude earthquake that struck the Kuril-Kamchatka subduction zone generated a tsunami that crossed the Pacific and produced an unusual record for science.
About 70 minutes after the quake, the SWOT satellite, a joint mission of NASA and the French space agency CNES, flew over the area and measured the deformation of the ocean surface in high resolution.
The record does not correspond to a conventional photograph, but to a detailed mapping of water height in open sea.
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According to NASA and the authors of the study, this is the first high-resolution space tracking of a major tsunami associated with a subduction zone.
What the SWOT satellite observed in the tsunami in the Pacific
The coincidence between the satellite’s passage and the wave’s advance allowed for a type of observation that is uncommon.
Previous altimetric missions had crossed tsunamis in open sea, but generally captured only a narrow strip of the ocean surface.
In the case of SWOT, the observed area was broader.
The instrument measured a strip of up to about 120 kilometers wide, with enough precision to show the shape of the wave front and the disturbances coming behind it.
In open sea, the height measured at the main crest exceeded 45 centimeters.
Although the number may seem limited, experts highlight that, in deep ocean, small variations in surface height represent the displacement of a large volume of water and can amplify in shallow coastal regions.
This range of observation helps explain the scientific interest in the case.
The buoys of the DART system, used in monitoring tsunamis in deep waters, remain central for alerts and point measurements.
Meanwhile, the satellite allows for observing the organization of the wave between these points.
Commenting on the usefulness of the data, oceanographer Angel Ruiz-Angulo from the University of Iceland stated that the set of measurements functions as “a new pair of glasses” for tsunami research.
The comparison was used to highlight the detail gained by the satellite compared to traditional instruments.
How the wave behaved in open sea
The data collected in the Kamchatka episode indicated a more complex pattern than described by simpler models.
Instead of a uniform front, the satellite recorded a field of waves with dispersion and secondary undulations behind the main crest.
In practice, this means that the tsunami energy did not advance in a unique and regular manner along the entire path.
According to the authors of the study, part of this energy was distributed into different components, which alters the shape of the wave as it propagates through the ocean.
The observation has implications for the mathematical modeling of these events.
According to the work published in the journal The Seismic Record, simulations that incorporated dispersion better reproduced the pattern observed by SWOT than models that disregarded this effect.
Researchers in the field assess that this type of difference can influence the estimation of the arrival time of the waves, the relative intensity between successive crests, and how water enters bays, ports, and coastal areas.
This does not invalidate the systems already used, but indicates the possibility of adjustments in future scenarios.
What the data revealed about the Kamchatka earthquake
The tsunami measurements also served to reassess characteristics of the earthquake that gave rise to the phenomenon.
By combining SWOT data with information from three nearby DART buoys, scientists revised the estimate of the seismic rupture along the fault.
Initial models indicated a rupture of about 300 kilometers.
With the new data inversion, the authors estimated a length close to 400 kilometers along the tectonic interface.
The study also calculated a peak uplift of around 4 meters and indicated that the model that combines tsunami data and seismic-geodetic deformation better explains the set of available observations.
According to the researchers, this type of combination improves the reconstruction of the event after the earthquake.
The analysis reinforces a point already known in seismology: the potential of a tsunami does not depend solely on the magnitude of the earthquake, but also on how the fault ruptures beneath the sea.
In the case of 2025, the authors identified similarities with segments of the megafault that ruptured in the 1952 earthquake, but with a different geometry.
According to the study, the rupture of 2025 occurred further inside the subduction interface, with no robust evidence of a very shallow rupture near the ocean trench.
This difference, according to the researchers, helps explain why the 2025 event had a large reach in the Pacific but a smaller impact than that associated with the historic earthquake of 1952.
Why the case gained importance for science
The Kamchatka earthquake has made it to the list of the largest ever recorded by modern instruments.
The United States Geological Survey, the USGS, classifies it among the six largest of the instrumental era.
NOAA, the U.S. agency responsible for oceanic and atmospheric monitoring, recorded that the tsunami was accompanied by an intense sequence of aftershocks and significant readings on DART buoys.
In one of them, the maximum amplitude reached 0.85 meters, one of the largest ever measured by this system.
This data has increased interest in the case because it offers a rare combination: an extreme earthquake, ocean measurements at different points, and a satellite overflight at the moment when the wave was still moving in open water.
For researchers, this set allows for comparison of models with direct observations on a scale that has been little available until now.
What changes in tsunami forecasting
Despite the scientific gain, the episode also highlighted an operational limit.
SWOT has recognized utility for post-event analysis and for improving models, but it does not replace alert systems that operate in minutes based on seismology, tide gauges, and ocean buoys.
Official mission documents indicate that the scientific products from the satellite still have a latency of days.
In technical materials related to the mission, this interval appears in ranges of about three to five days for routinely processed products, although there are efforts to reduce this timeframe in near real-time applications.
Therefore, the current role of the satellite is more related to the detailed reconstruction of major events and testing models used by researchers.
Still, the Kamchatka case has begun to be cited as an example of the potential of space altimetry to enhance understanding of tsunami propagation in open water.
More than just recording the passage of the wave, the overflight allowed for observation of how the tsunami organized itself over hundreds of kilometers.
For specialists, this type of evidence can help revise hypotheses about the physics of these waves and calibrate, with greater precision, tools used in coastal risk studies.
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