GSA QUATERNARY GEOLOGY AND GEOMORPHOLOGY DIVISION ARTHUR D. HOWARD AWARD: IMPACTS OF RAPID CLIMATE WARMING ON THE FREQUENCY AND SPATIAL DISTRIBUTION OF LANDSLIDES IN A SUBARCTIC MOUNTAIN RANGE, DENALI NATIONAL PARK AND PRESERVE, ALASKA

Denali National Park and Preserve (DENA) is a crown jewel within the US National Park system. It receives over 600,000 visitors a year, most of whom travel the 140-km road traversing the northern flank of the park. This road is increasingly threatened by a wide range of mass movement types, some of which are related to the thawing of permafrost, or perennially frozen ground, as climate warms. Landslides along the DENA road corridor are both an urgent management issue and an interesting case study into how climate change impacts hillslope geomorphology in a subarctic mountain range. We hypothesize that mass movements in DENA have increased in frequency because of post-Little Ice Age warming, and further that landslides are most frequent on north-facing slopes because active layers (depth of seasonal freeze-thaw) are thinnest there and have been less affected by past climatic fluctuations. To test these hypotheses, we classified mass movements using the Varnes system modified for periglacial environments, mapped their occurrence in a GIS database to test for differences in aspect frequency, and used remote sensing imagery and lichenometry to estimate initial failure dates. Preliminary results confirm that landslide frequency has increased over the last several decades, corroborate observations that permafrost thaw is frequently involved in landslide initiation, and suggest that slope aspect is a useful predictor of landslide occurrence.