A 481-meter-high landslide-tsunami in a cruise ship–frequented Alaska fjord
Abstract
Early in the morning of 10 August 2025, a >64 × 10 6 –cubic meter landslide struck Tracy Arm fjord in Alaska. The landslide was preconditioned by glacial retreat caused by climate change. The resulting 481-meter runup megatsunami followed an initial 100-meter-high breaking wave traveling at >70 meters per second. The landslide was preceded by several days of microseismicity, which increased in rate and magnitude until ~1 hour before failure. The landslide produced globally observed long-period seismic waves equivalent in size to a moment magnitude 5.4 earthquake. A long-period (~66 second) global seismic signal, produced by a landslide-induced seiche trapped within the fjord, persisted for up to 36 hours, the second time a days-long seiche had thus been observed. With fjord regions increasingly visited by cruise ships, and climate change making similar events more likely, this unanticipated, near-miss event highlights the growing risk from landslides and tsunamis in coastal environments.
Article Details
Journal Info
Science
American Association for the Advancement of Science
Authors (19)
Dan H. Shugar
Water, Sediment, Hazards, and Earth-Surface Dynamics (waterSHED) Lab, Department of Earth, Energy, and Environment, University of Calgary, Calgary, AB, Canada.
Katherine R. Barnhart
US Geological Survey, Geologic Hazards Science Center, Golden, CO, USA.
Mira Berdahl
Earth and Space Sciences Department, University of Washington, Seattle, WA, USA.
Jacqueline Caplan-Auerbach
Geology Department, Western Washington University, Bellingham, WA, USA.
Göran Ekström
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA.
Aram Fathian
Water, Sediment, Hazards, and Earth-Surface Dynamics (waterSHED) Lab, Department of Earth, Energy, and Environment, University of Calgary, Calgary, AB, Canada.
Marten Geertsema
Ministry of Forests, Prince George, BC, Canada.
Stephen P. Hicks
Department of Earth Sciences, University College London, London, UK.
Bretwood Higman
Ground Truth Alaska, Seldovia, AK, USA.
Erin K. Jensen
US Geological Survey, Geologic Hazards Science Center, Golden, CO, USA.
Ezgi Karasözen
Alaska Earthquake Center, Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA.
Patrick Lynett
Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA, USA.
John Lyons
US Geological Survey, Alaska Volcano Observatory, Anchorage, AK, USA.
Thomas Monahan
Department of Engineering Science, University of Oxford, Oxford, UK.
Gerard Roe
Earth and Space Sciences Department, University of Washington, Seattle, WA, USA.
Kristian Svennevig
GEUS, Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
Liam Toney
US Geological Survey, Geologic Hazards Science Center, Golden, CO, USA.
Maximillian Van Wyk de Vries
Complex and Multihazard Research Group (CoMHaz), Departments of Earth Sciences and Geography, University of Cambridge, Cambridge, UK.
Michael E. West
Alaska Earthquake Center, Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA.