Satellite Observations of Kamchatka Tsunami

The NASA/CNES Surface Water and Ocean Topography (SWOT) satellite obtained direct observations of the 2025 Kamchatka tsunami. This event followed a magnitude 8.8 earthquake on July 29, 2025. The satellite flew over the region approximately 70 minutes after the tsunami began, providing high-resolution two-dimensional measurements of sea-surface height with centimeter-level precision.

Unprecedented Insights

Researchers, led by Ignacio Sepúlveda, report that SWOT captured the full wavefield, including short-wavelength wave trains. These observations revealed the directions, curvature, and wavelengths of the tsunami waves.

Analysis of the data indicates the tsunami generated within approximately 10 kilometers of the subduction-zone trench.

Implications for Tsunami Research

These findings offer insights not previously possible with land-based measurements or seafloor sensors alone, which are often limited by sparse coverage and signal attenuation. The direct link between detailed, two-dimensional satellite observations and the tsunami's near-trench source represents the first high-resolution spaceborne evidence of tsunamigenesis.

This establishes SWOT as a significant tool for understanding earthquake source processes, tsunami hazards, and the dynamics of subduction zones.