Katherine R. Barnhart Mira Berdahl Jacqueline Caplan-Auerbach Göran Ekström Aram Fathian M. Geertsema Stephen P. Hicks Bretwood Higman Erin K. Jensen Ezgi Karasozen Patrick J. Lynett John J. Lyons Thomas Monahan Gerard H. Roe Kristian Svennevig Liam Toney Maximillian Van Wyk de Vries Michael E. West Dan H. Shugar 2026 <p><span>Early in the morning of 10 August 2025, a &gt;64 × 10</span>⁶<span>–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 &gt;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.</span></p> application/pdf 10.1126/science.aec3187 en American Association for the Advancement of Science A 481 m-high landslide-tsunami in a cruise ship-frequented Alaska fjord article