2019 Geohazard AnalysisThe data below illustrates the most severe weather-related geohazards that developed on the Denali Park Road during August 2019. The data is evaluated using a "SPE" model—Severity, Probability, Exposure. The model assigns a numeric value to each geohazard event based on its severity, its probability to recur, and its exposure. The values are multiplied, and an overall score from 1 to 100 is the result. A high score indicates a bigger risk or problem. A brief description of the event, the mitigation of it, and notes for the future are also available in the dataset.
Pretty Rocks LandslideSection last updated: April 2, 2019 Igloo Debris Slide2018On September 30th and October 18th 2018, the Igloo Debris Slide partially blocked the Denali Park Road. In each event, the Denali road crew cleared approximately 500 cubic yards (450 m3) from the roadway within a few hours. Like the 2013 event, 12’ (4 m) blocks of ice-rich, unconsolidated debris slid on the same or similar unfrozen clay layer. 2013 and 2018 both experienced unusually mild fall weather. Such weather further thaws permafrost, which decreases cohesion and increases pore water pressure. Therefore, this combination of processes can cause and trigger landslides. As more permafrost has thawed and the slide has continued to move, the area of the slide has increased. Several smaller events have filled the road ditch since September 30th. 2013In late October 2013, road maintenance staff discovered that a 600’ (180 m)-long, 110’ (35 m)-wide debris slide had blocked the park road near Mile 38.
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Last updated: January 12, 2023