A 481-meter-high landslide-tsunami in a cruise ship-frequented Alaska fjord
Summary
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 s
Content
# A 481-meter-high landslide-tsunami in a cruise ship-frequented Alaska fjord
*Published: 2026 May 6*
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.
DOI: 10.1126/science.aec3187