1,500-foot tsunami, massive landslide reshape Alaska’s Tracy Arm fjord

A rapid retreat of South Sawyer Glacier triggered a massive rockslide into Tracy Arm fjord on Aug. 10, 2025.

The collapse released about 64 million cubic meters of rock, generated a seismic signal, and drove a tsunami estimated at roughly 1,578 feet high.

Water continued oscillating for more than 24 hours, leaving no fatalities but causing major landscape change.

Scientists say the event highlights how glacier retreat can rapidly destabilize steep fjord walls and amplify tsunami risk in warming coastal regions.