Massive 1,500-Foot Tsunami Hits Alaska’s Tracy Arm Following Landslide

A massive landslide in Alaska’s Tracy Arm fjord in August 2025 triggered a tsunami that reached a height of 1,500 feet. The event occurred in a fjord located southeast of Juneau, where a significant volume of earth collapsed into the ocean.

Despite the presence of tour boats in the water during the collapse, all individuals on the vessels survived the event. The wave now stands as the second largest tsunami ever recorded.

Scientific Analysis of the Landslide

Researchers analyzing the event used digital elevation models and imagery from before and after the slide to quantify the collapse. They estimate that at least 2.26 billion cubic feet of earth fell into the water, resulting in the loss of approximately 500 feet of coastline.

While the available data confirms the coastal loss, researchers believe the rupture likely extended further below the water’s surface. However, they currently lack the necessary bathymetry data to prove the full extent of the underwater collapse.

The resulting tsunami reached more than 1,500 feet up the side of the fjord and sloshed back and forth like bathtub water, creating a seismic ‘ringing’ that could be detected around the world for up to 36 hours. — Dan Shugar, lead author of the study, via Scientific American

Comparison to the Lituya Bay Event

The 2025 event is compared to the record-holding tsunami that occurred in Lituya Bay, also in Alaska. That event took place on a night in July 1958, following an earthquake that occurred 13 miles away.

The 1958 tremor caused approximately 30.6 million cubic meters of rock to fall 3,000 feet into the Lituya Glacier. This displaced a massive volume of water, creating a wave that reached 1,720 feet.

According to the United Nations Office for Disaster Risk and Reduction, the 1958 wave claimed five lives. Similar to the August 2025 event, some individuals on boats in the water survived the 1958 tsunami.

Future Risks and Witness Accounts

Researchers have expressed concern that similar landslide-induced tsunamis could occur again in the region. The scale of these events demonstrates the volatility of the Alaskan coastline and the potential for sudden, massive water displacement.

Christine Smith, who was aboard a boat in the water during the August 2025 event, spoke with Scientific American about the experience and the lasting impact of the disaster.

We all go to these beautiful places because we want to experience the beauty, and we want to be humbled by nature. That scar that is there by the glacier is always going to be a reminder that this has happened there, and it can happen anywhere else. — Christine Smith, via Scientific American