Derek Cronmiller
The phenomenon occurred in December 2024 and permanently altered the geology of the area, with the bed of the Takhini River reducing by half.
A massive landslide in Canada’s Yukon Territory last December triggered a rare “tsunami de gelo“, sending huge sheets of frozen river ice across the landscape and flattening trees in their path. The phenomenon was reported in a new publication in Landslides on September 25th.
The event took place at December 17, 2024when a steep slope above the Takhini River, about 25 kilometers northwest of Whitehorse, suddenly gave way. Approximately 118,000 cubic meters of earth and rocks plunged into the frozen river, sending a wave of ice and debris which swept the banks of the river and threw blocks of ice up to 250 meters away.
“This effect is an important consideration for future risk assessments of landslides and tsunamis in cold regions,” said Derek Cronmiller, a permafrost geologist with the Yukon Geological Survey and lead author of the study. Cronmiller visited the remote location 24 days after the event and described the extraordinary strength of ice-laden wave.
The ice tsunami destroyed 7.2 hectares of the river and surrounding land. On the opposite bank, almost all the trees were broken or uprooted, leaving only the four largest. According to , only trunks larger than 30 centimeters in diameter survived. Huge sheets of ice, measuring around four square meters, were discovered hundreds of meters from the landslide zone, some overturned and covered by layers of sand, indicating that the wave had torn away parts of the riverbed.
Although summer slides often produce larger waves in open water, Cronmiller’s investigation suggests that winter ice actually limited destruction to a smaller areaalthough the ice chunks themselves amplified the impact locally.
Happily, no one was injured. The Takhini River is popular with dog sledders and snowmobilers in winter and rafters in summer, but the incident occurred in a sparsely populated area.
Still, the consequences will persist. The slide reduced the width of the river by half and filled it with debris that could pose risks to paddlers and wildlife for years. Cronmiller estimates that it will take more than a decade for the Takhini River to break through the blockage naturally, through erosion.
