A massive rockfall in an Alaskan fiord last year triggered one of the largest tsunamis ever documented, with a colossal 481-meter wave surpassing the CN Tower’s highest observation deck, a recent study reveals. The study’s lead author, Dan Shugar, a University of Calgary associate professor, emphasizes the significant risk posed by such events and calls for increased attention from policymakers, especially in British Columbia.
The research, published in Science journal, highlights that the tsunami near the Alaska-B.C. border was likely caused by a glacier retreat that cleared the path for the landslide. As global warming continues and infrastructure expands, the threat of landslide-induced fiord tsunamis is escalating, potentially leading to future disasters, the study warns.
The study details the landslide that occurred at 5:26 a.m. on Aug. 10, 2025, when over 64 million cubic meters of rock plunged 1,000 meters into Tracy Arm Fjord, resulting in a wave run-up of about 481 meters, the second highest ever recorded. Despite the fiord’s regular cruise ship traffic, only one ship was present during the tsunami, narrowly avoiding catastrophe.
The researchers note the unusual nature of the landslide in Tracy Arm and stress the importance of monitoring similar areas for potential hazards. They attribute the significant glacier retreat in the vicinity to human-induced climate change, underscoring the direct link between warming temperatures and glacier instability. The study draws a vivid analogy likening the landslide’s impact to a closet full of teddy bears spilling out when a latch is released.
While advocating for caution and monitoring of high-risk areas, the researchers do not propose restricting maritime activities off the Canadian coast. However, with the increasing cruise and tanker traffic, particularly in light of discussions about a new oil pipeline, the potential threat of tsunamis must be considered. Early warning systems utilizing seismic activity data prior to such events could play a crucial role in mitigating future risks.
The Geological Survey of Canada is already evaluating fiord hazard potential, but a national-level policy approach is recommended to address and prevent future disasters.
