The Hooskanaden Landslide: historic and recent surge behavior of an active earthflow on the Oregon Coast

• DOI: 10.1007/s10346-020-01466-8
• Publication Date: 2020-06-25T06:02:45Z
• Authors: Stefano Alberti; Andrew Senogles; Kara Kingen; Adam Booth; Pete Castro; Jill DeKoekkoek; Kira Glover-Cutter; Curran Mohney; Michael Olsen; Ben Leshchinsky
• Keywords: Vertical displacement

This paper presents an analysis of the Hooskanaden Landslide, an earthflow, which experienced a dramatic surge event beginning on February 24, 2019, closing US Highway 101 near mile point 343.5 for nearly 2 weeks. This ~ 1 km long surge event resulted in horizontal displacements of up to 45 m and uplift of 6 m at the toe located on a gravel beach adjacent to the Pacific Ocean. The Hooskanaden Landslide, likely active since the eighteenth century, exhibits regular activity with a recurrence interval of major surge events of approximately every 20 years, transitioning from slow to relatively rapid velocities. During the 2019 event, maximum displacement rates of approximately 60 cm/h were observed, slowly decreasing to 15 cm/h for a sustained period of approximately 2 weeks before the eventual return to baseline conditions (< 0.02 cm/h).