Scientists Identify Warning Signs for Landslide Tsunamis After 2025 Alaska Event
On August 10, 2025, a landslide of 2.3 billion cubic feet of rock—24 times the volume of the Great Pyramid of Giza—fell into Tracy Arm fjord, 45 miles south of Juneau, Alaska, triggering a mega-tsunami with a wave reaching 1,580 feet. Despite being the second-largest landslide-induced tsunami on record, no one was injured. A study published in Science on May 6, 2026, led by Dan Shugar (University of Calgary), Michael E. West, Ezgi Karasözen (University of Alaska Fairbanks), Jackie Caplan-Auerbach (Western Washington University), and Aram Fathian (University of Calgary), used satellite images, eyewitness accounts, earthquake data, and computer simulations to identify precursors. The nearby South Sawyer Glacier had rapidly shrunk, exposing unstable rock. Earthquake sensors detected small repeating tremors in the days before, accelerating from once per hour to every 30-60 seconds before the collapse. The team says these signals could have warned boats to stay out of the fjord. Climate change-driven glacier retreat increases risk, and researchers plan to develop early warning systems.
Key facts
- Landslide occurred August 10, 2025, at 5:26 am local time.
- 2.3 billion cubic feet of rock fell into Tracy Arm fjord, Alaska.
- Volume equivalent to 24 times the Great Pyramid of Giza.
- Mega-tsunami wave reached 1,580 feet above sea level.
- Second-largest landslide-induced tsunami on record.
- No injuries reported; kayakers on Harbor Island lost gear.
- Study published in Science on May 6, 2026.
- South Sawyer Glacier retreat exposed unstable rockface.
- Seismic precursors detected: small repeating earthquakes accelerating before collapse.
- Researchers: signals sufficient for time-sensitive warning.
- Climate change accelerates glacier retreat, raising risk.
- Team plans to investigate warning signs for early warning systems.
Entities
Institutions
- University of Calgary
- University of Alaska Fairbanks
- Western Washington University
- University of California, Santa Cruz
- U.S. Geological Survey
- Alaska Public Media
- New York Times
- Ars Technica
- Science
- The Conversation
Locations
- Tracy Arm fjord
- Juneau
- Alaska
- Harbor Island
- Endicott Arm
- Iliamna Volcano
- Arctic
- Canada