Last December, a landslide struck a river in Canada’s Yukon Territory, causing a tsunami of slabs of ice to fly over two soccer fields, shearing trees in the process.
Now, new research suggests that the damage caused by this “ice tsunami” was exacerbated by the destructive power of river ice. However, it was confined to a smaller area than when landslides occur in the summer and produce ice-free waves.
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The ice tsunami occurred on December 17, 2024, when a steep slope above the Takini River collapsed without warning. Approximately 4.1 million cubic feet (118,000 cubic meters) of debris fell into the river, which was covered in ice at the time. The impact created an ice-studded tsunami that swept away 17.8 acres (7.2 hectares) of the river and its banks. River ice broke up to 820 feet (250 meters) away, and chunks of ice more than 43 square feet (4 square meters) were found 656 feet (200 meters) from the landslide.
Waves of ice washed away vegetation on the riverbank, stripping all but the four largest trees from the bank opposite the landslide. Only trees with a trunk diameter of more than 30 centimeters survived on the slope.
Some river ice slabs were overturned and had about 4 inches to 1 foot (10 to 30 cm) of sand on them. Cronmiller wrote that the planks froze solid to the bottom of the river, which was also torn apart by the force of the tsunami.
Landslides are typically caused by snowmelt, rainfall, or human activity, but Cronmiller found no evidence of external factors in the Dec. 17 earthquake. Instead, the slope suffered a “brittle failure,” meaning it cracked without any signs of warping or deformation.
Fortunately, no one was injured in the incident, which occurred in a rural area 15.5 miles (25 kilometers) northwest of Whitehorse, Yukon Territory. However, the river is a destination for outdoor activities. Dog sleds and snowmobiles use it as a thoroughfare in the winter, and river rafters cross the Takini River in the summer.
Cronmiller wrote that the landslide narrowed the river by 50% and could clog it with debris, making it dangerous for paddlers for years to come. A new study has found that it will likely take more than a decade for the Takini River to cut through the debris of the landslide and recover.
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