From Public Hazard to Key Drivers of Landscape Change: Understanding the Role of Avalanches in Southeast Alaska

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a forested mountainside

Tree Ring Research; Credit: Molly Tankersley

Southeast Alaska
Apr 2018 to Jun 2019

The City and Borough of Juneau, Alaska has the highest urban avalanche danger in the U.S., with regular impacts to people, property, critical infrastructure, and natural resources. Avalanche hazard zones occur over a large area extending from downtown Juneau to the Snettisham power plant 50 km to the south, the Kensington Mine 60 km to the north, and the Eaglecrest Ski area 6 km to the west. Developing a better understanding of avalanches and the processes leading to avalanche formation in the Juneau area is critical. This information would greatly aid local and regional efforts to forecast avalanches and update avalanche hazard maps, including the risk to transportation, utility, and mining corridors.

An important step in improving avalanche forecasting is identifying whether past avalanches were associated with particular climate or weather patterns. Certain variables, such as temperature and the amount and type of precipitation, can create the snowpack conditions that are necessary for widespread avalanche formation. Further, large scale climate patterns, such as El Niño/La Niña and the Pacific Decadal Oscillation, can have substantial effects on snowpack. However, there are no consistent historical records of avalanche incidence in Juneau. As a result, researchers will use dendrochronology – the study of tree rings – to date past large avalanche events in Juneau. They will then use monthly climate data to identify any relationships that may exist between avalanche activity and different climate and weather variables.

Changing climate conditions in southeast Alaska could alter future avalanche activity. This project responds directly to stakeholder needs by producing information and products that will help Juneau-area resource managers and emergency response personnel more clearly understand the potential impacts of a changing climate on avalanche activity. The project will result in a comprehensive record of avalanche occurrence and magnitude for the Juneau area, which will support local, state, federal, and private sector efforts to forecast future avalanche activity and update avalanche hazard maps.