MORISAWA AWARD: LANDSLIDE RESPONSE TO CLIMATE CHANGE IN PERMAFROST REGIONS

Rapid permafrost thaw in the arctic and subarctic increases hillslope susceptibility to landsliding by altering physical and hydrologic properties of hillslope materials, including reduced cohesion and increased hydraulic connectivity. In this presentation, we evaluate the fundamental processes that increase landslide frequency in regions of permafrost thaw and the short term topographic response of hillslopes to shallow-angle landslides. We synthesize remote analysis with field methods including surficial geologic mapping and time-series terrestrial lidar surveys of small (<0.5 km²) landslides in Denali National Park and Preserve, Alaska. Notably, landslides primarily occur in susceptible lithologies (unconsolidated glacial deposits and weathered felsic volcanics) and on hillslopes with a bimodal distribution of slope angles. These results suggest that permafrost or ice-related processes are generating landslides on shallow angles, while rainfall-dominated initiation occurs at steeper slope angles. These shallow landslides result in topographic signatures that influence snow accumulation for at least two years. We also use a review of the literature and analysis of primary data to address five questions of fundamental and practical importance and suggest three key areas for future research and primary data production to fill gaps in the understanding of landslide regimes in permafrost regions.