HR: 1340h
AN: GC33A-1248    [Abstracts]
TI: Climate Influences on Large-Magnitude Natural Snow Avalanches in John F. Stevens Canyon, Montana
AU: * Reardon, B A
EM: blase_reardon@usgs.gov
AF: USGS Northern Rocky Mountain Science Center, Glacier National Park, West Glacier, MT 59936 United States
AU: Fagre, D B
EM: dan_fagre@usgs.gov
AF: USGS Northern Rocky Mountain Science Center, Glacier National Park, West Glacier, MT 59936 United States
AU: Pederson, G T
EM: gpederson@montana.edu
AF: Big Sky Institute Montana State University, 106 AJM Johnson Hall P.O. Box 173490 Montana State University, Bozeman, MT 59717 United States
AU: Caruso, C J
EM: christiancaruso@mac.com
AF: Big Sky Institute Montana State University, 106 AJM Johnson Hall P.O. Box 173490 Montana State University, Bozeman, MT 59717 United States
AB: Snow avalanches are usually characterized as natural hazards. Most literature describes mitigation measures or snow properties and weather processes that contribute to avalanche initiation, with recent research focusing on the spatial variability of snow properties. Some analyses have linked extreme avalanche events (those marked by widespread, large-magnitude, destructive avalanches) with synoptic weather patterns. This study examines the temporal variability of large magnitude natural avalanches in John F. Stevens Canyon in Montana using a long-term (96 winters) historic record and dendrochronology. Results show that shifts in multi-decadal climate patterns such as the Pacific Decadal Oscillation change the frequency and severity of large-magnitude natural avalanches. From their immediate impacts, which include downed trees and dammed streams, such events appear destructive. Cumulatively, however, these events create ecotones and structural diversity in montane forests and dampen reforestation after wildfires. Large magnitude natural avalanches are thus recurring, climate-influenced disturbances that have significant, long-lasting, landscape-level effects. However, potential changes in multi-decadal climate patterns and projected changes in snowpack may lead to changes in natural avalanche frequency and severity, and thus long-term, landscape scale changes in montane forests in the northern Rocky Mountains.
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
SC: Global Climate Change [GC]
MN: Fall Meeting 2005