The Slate Creek Landslide (SCL) is an active complex landslide including elements of an earth slump and an earth flow. Despite its location in the discontinuous permafrost zone within the northern foothills of the Alaska Range, permafrost thaw appears to be of minor importance. The SCL experienced a quiescent interval of at least several decades before beginning a period of rapid movement in the mid 1960s. Major episodes of tree leaning occurred in 1967, indicating surges of ground motion occurring in 1973, 1977, and 2017. Widespread tree-splitting followed the initial period of tree leaning and peaked ca. 1980. The landslide has been extremely active over the last several years, with movement up to 8m per year in 2020 and 2021. Major episodes of landslide motion appear to coincide with anomalously wet periods, with peaks in positive precipitation anomalies occurring 1 to 3 years prior to peaks in movement on the SCL. The upper portion of the landslide is now moving significantly faster than its toe, indicating that a wave of accelerating motion will progress downslope over the coming decade. What caused the mid-1960s reactivation of this mass movement is still unclear, but it may be the result of road construction with continued movement driven by years of increased precipitation. At its present rate of motion, the SCL will force the realignment of the Parks Highway over the next decade or two. Of immediate concern is the breaking of a newly laid, transcontinental fiber-optic cable that was placed over the landslide’s toe in 2020.
