In July 2025, a magnitude 8.8 earthquake struck off Russia's Kamchatka Peninsula, triggering a massive local tsunami. While waves reached 20 meters near the coast, they remained smaller across the Pacific than those from a 1952 quake. Experts said, "The earthquake's size mattered, but so did where the rocks moved."
In 2025, along parts of Kamchatka's coast in Russia, a magnitude 8.8 earthquake caused a tsunami to surge nearly 20 meters (65 feet) above sea level. Yet across the Pacific, its waves were much smaller than those produced by the region's great 9.0 earthquake in 1952. How could the tsunami climb so high near the source yet have a comparatively modest impact far away?
The November 1952 quake located close to Kamchatka sent destructive waves across the ocean. The resulting tsunami destroyed most of Severo-Kurilsk, a town in the Kuril Islands. Even in distant Hawaii, it wrecked boats and piers and demolished a bridge linking Hilo's shore to Coconut Island. Its destruction both near and far makes it a compelling comparison to the 2025 event.
A new reconstruction of the later earthquake published in Communications Earth & Environment by Stefano Lorito of Italy's National Institute of Geophysics and Volcanology and colleagues points to what happened beneath the seabed. The earthquake's size mattered, but so did where the rocks moved—a difference that helps explain the two tsunamis' contrasting effects.
A wave caught from orbit
The magnitude 8.8 earthquake struck off Russia's Kamchatka Peninsula in July 2025. As the seabed shifted, it displaced the water above it, sending waves across the Pacific. Warnings went out around the ocean, then were scaled back as measurements revealed a smaller tsunami than early forecasts had suggested.
One revealing observation came from space. About 70 minutes after the earthquake, the Surface Water and Ocean Topography satellite, known as SWOT, passed overhead and measured the tsunami spreading through the open ocean.
Lorito and colleagues combined those observations with readings from seabed sensors and measurements of how the earthquake shifted land. Working backward from these clues, they reconstructed the underground movement that could explain what had happened at the surface.
Less energy, but still a huge local surge
Most of the movement happened well below the seabed. That helped limit the energy passed into the tsunami, even though the earthquake itself was enormous.
The team estimates that the tsunami started with only about a tenth to a fifth of the energy of its 1952 predecessor. Together, the smaller earthquake and the depth of much of its movement help explain why distant shores experienced weaker waves.
But that left the other half of the puzzle: The water still reached heights near Kamchatka that were comparable to those in 1952.
The reconstruction showed that some movement occurred closer to the seabed, including a stretch that reached the ocean trench. This helped generate waves that could grow dramatically as they approached land.
Waves traveling from deep water into the shallows slow down and grow taller. The shape of the seabed and the slope of the coast further influence how high they climb. Those local conditions, combined with the shallower movement, helped turn a less energetic tsunami into a powerful surge along nearby shores. The water reached nearly 20 meters on land, but out in the Pacific, the waves were far lower.
The challenge for forecasters
Forecasters cannot see all these underground details when an earthquake first strikes. They can estimate its size quickly, but a more complete picture of how it moved the seabed takes longer to emerge. The researchers stress that cautious warnings remain essential in order to protect lives while that picture is developing.
Kamchatka shows why that matters. One earthquake can send relatively modest waves toward distant countries while driving a dangerous surge onto its own coast.
The research does suggest that combining more ocean and land sensors with improved simulations could help refine forecasts sooner. In addition, warning centers could use early wave measurements alongside earthquake data to refine alerts as a tsunami travels.