Landslides don't have to move fast to be powerful.
In Denali National Park in Alaska, the 300-ft-wide Pretty Rocks landslidelocated at about Mile 45.4 of the Park Road, has been active for decades, moving just inches per year. Yet over recent years, the rate of debris acceleration has increased so dramatically that the National Park Service had to close the roadway in August 2021, cutting off access to the western half of the popular park.