Alaska Megatsunami: Glacier Collapse Triggered Massive Wave Visible From Space, NASA Images Reveal

A massive landslide in Tracy Arm Fjord triggered a powerful megatsunami in summer 2025, stripping forests, reshaping shorelines, and leaving destruction so vast that it was visible from space. Scientists say the disaster was caused by the rapid retreat of the South Sawyer Glacier, raising fresh concerns about climate-driven geological hazards in glacier regions.

The catastrophic event reached its peak on August 10, 2025, when at least 64 million cubic meters of rock crashed into the fjord waters after the unstable mountainside collapsed. The impact unleashed a towering tsunami wave that ripped trees and vegetation from slopes up to 1,578 feet above sea level, devastating large stretches of the surrounding landscape within minutes.

Satellite images captured by NASA and the United States Geological Survey showed the dramatic transformation of Tracy Arm before and after the megatsunami. Images taken in late July and again on August 19 revealed a giant landslide scar on the fjord wall and a visible “bathtub ring” where forests had been wiped out by the massive wave. Tsunami Waves Observed in Various Locations After 7.5-Magnitude Earthquake in Japan

Dan Shugar, who led the study published in the journal Science on May 6, 2026, said the satellite comparison made the scale of destruction “impossible to miss.” Researchers combined satellite data, airborne surveys, simulations, and eyewitness accounts to reconstruct the disaster.

Their analysis found that water continued sloshing around the fjord for more than 24 hours after the collapse. The landslide and resulting seiche generated seismic signals detected around the globe, with the energy equivalent to a magnitude 5.4 earthquake. Tsunami in Alaska: Mega-Landslide Triggers Silent Tsunami 100-Foot Waves Near Juneau (Watch Video)

Despite the extreme conditions, there was no loss of life. Kayakers camping near the fjord lost equipment when waves surged through the area, while passengers aboard a nearby cruise vessel reported sudden swings in water levels and powerful currents as the tsunami passed.

Scientists say the event highlights the growing danger posed by rapidly retreating glaciers. The South Sawyer Glacier had pulled back dramatically in the weeks leading up to the collapse, exposing unstable slopes and increasing the risk of landslides and tsunamis.

Experts now warn that satellite monitoring of glacier retreat could become critical for identifying future megatsunami risk zones in remote regions like Alaska, where climate change is rapidly transforming the landscape.

(The above story first appeared on LatestLY on May 17, 2026 06:01 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).