2026-05-06 ワシントン大学（UW）
Before-and-after satellite imagery showing locations and extent of the Aug. 10 landslide and progression of glacial retreat since 1979. On the right, the white line shows the landslide area and the yellow on the opposite bank shows tsunami runup. Photo: Planet Labs
＜関連情報＞
- https://www.washington.edu/news/2026/05/06/near-miss-tsunami-in-alaska-during-tourist-season-last-year-highlights-increasing-environmental-instability/
- https://www.science.org/doi/10.1126/science.aec3187
クルーズ船が頻繁に訪れるアラスカのフィヨルドで、高さ481メートルの地滑り津波が発生 A 481-meter-high landslide-tsunami in a cruise ship–frequented Alaska fjord
Dan H. Shugar, Katherine R. Barnhart, Mira Berdahl, Jacqueline Caplan-Auerbach, […] , and Michael E. West
Science Published:6 May 2026
DOI:https://doi.org/10.1126/science.aec3187
Abstract
Early in the morning of 10 August 2025, a >64 × 106 m3 landslide struck Tracy Arm fjord in Alaska. The landslide was preconditioned by glacial retreat caused by climate change. The resulting 481 m runup megatsunami followed an initial 100-m-high breaking wave traveling >70 m s−1. 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 M5.4 earthquake. A long-period (~66 s) 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 has been thus 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.
