On August 10, 2025, a massive landslide struck Tracy Arm fjord, in Alaska, displacing water and generating a giant wave that crashed onto the opposite slope at more than 150 miles per hour. Within minutes, the landslide caused seismic effects equivalent to a magnitude 5.4 earthquake, and the resulting tsunami is believed to be among the tallest ever recorded, at approximately 1,600 feet.

Vegetation was stripped along the shoreline, but there were no fatalities. At a different time, the Tracy Arm would have been crowded with cruise ships and smaller sightseeing boats, potentially resulting in catastrophic loss of life and property. The landslide was preceded by the rapid retreat of a glacier, which may have lubricated the slope.

In a study published in Science, researchers examined the Tracy Arm event to determine if it could have been predicted. Although optical and radar remote sensors, along with high-resolution images from the days and weeks before the event, showed no signs of the rock face being at risk of collapse, there was an increase in micro-seismic activity at least 24 hours before the landslide, intensifying in the hours leading up to the event.

Considering the magnitude and far-reaching risks of a similar landslide-tsunami in heavily trafficked areas, the researchers recommended systematic monitoring of unstable slopes, realistic tsunami scenarios and protective measures for local communities, tourists and critical infrastructure.