A joint U.S.–French Earth-observing satellite has captured one of the clearest space-based views of a tsunami to date, offering a real-world check on models that underpin coastal warning systems. NASA and France’s CNES Surface Water and Ocean Topography (SWOT) mission recorded the tsunami generated by a powerful magnitude-8.8 earthquake off Russia’s Kamchatka Peninsula on July 30, tracking the wave field roughly 70 minutes after the rupture.
What the satellite actually saw
Using its Ka-band Radar Interferometer, SWOT measured subtle rises and falls in sea level along its wide “swath” across the Pacific, mapping the tsunami’s leading edge with uncommon detail. At its peak along the satellite track, the crest exceeded about 45cm (roughly 1.5ft) in the open ocean—small to the eye, but scientifically significant. Because tsunamis displace the entire water column from seafloor to surface, a modest open-ocean signal can steepen dramatically in shallower coastal waters, where local seafloor shape and coastline geometry can turn decimeters into multi-meter run-up.
Why this matters for warnings
Scientists at NOAA’s Center for Tsunami Research compared SWOT’s observations with one of their operational forecast models, and the match was strong. That alignment—between a physics-based forecast and a real-world satellite snapshot—builds confidence in the timing, shape, and strength of predicted waves used to issue alerts. In practice, better validation means forecasters can set thresholds with greater precision and refine advisories during the crucial hours after a major quake.
A long-sought capability
Since the 2004 Sumatra-Andaman disaster, tsunami modelers have worked to merge sparse deep-ocean sensors, seismic data, and complex hydrodynamics into timely, reliable guidance. But getting a broad, independent look at the wave field over the open ocean has been rare. SWOT changes that calculus by providing a wide-area, high-resolution view in a single pass—exactly the kind of “truth data” forecasters need to check their assumptions while an event is unfolding.
The mission behind the measurement
SWOT is a partnership led by NASA and CNES with key contributions from the Canadian Space Agency and the UK Space Agency. It’s designed to map the height and movement of water across Earth’s oceans, lakes, and rivers with unprecedented breadth and precision. For tsunamis, the payoff is clear: capturing the wave’s fingerprint over hundreds of kilometers, then feeding that back into models that help determine when to evacuate and where the greatest risks lie.
The bottom line
- A magnitude-8.8 earthquake near Kamchatka on July 30 generated a tsunami that SWOT captured about 70 minutes after the quake.
- The satellite measured an open-ocean crest of roughly 45cm, providing a clean, wide-area view of the wave’s height, shape, and direction.
- NOAA’s forecasts closely matched what SWOT observed, strengthening trust in operational models used for coastal warnings.
- The event marks a step-change in how satellites can support tsunami prediction—turning space-based snapshots into practical gains for public safety.