Abstract: The effects of permafrost degradation in Yukon have serious negative implications for the structural integrity of vertical infrastructure. This is especially pertinent for critical buildings such as hospitals, schools, etc., in small communities that are situated on top of warm, ice-rich permafrost. Projections of mean annual air temperature over the next few decades, based on regional climatic models, indicate that air temperature will rise, hastening the thaw of permafrost. The combination of rising of air temperatures and buildings situated on warm permafrost has prompted this investigation into the vulnerability of Yukon Government vertical infrastructure. The application of DC resistivity and ground penetrating radar in conjunction with borehole drilling indicates that in Dawson there is warm ice-rich permafrost beneath the Palace Grand Theatre; the Old Territorial Administration building is underlain by primarily unfrozen sediment; and permafrost under the St. Andrew’s Church is characterized by high variability. A deep active layer was observed at Ross River School and geophysical surveys indicate that warm water drainage from the roof is contributing to the thaw of the underlying permafrost.

Authors: Laxton, S. and Coates, J.

Keywords: borehole drilling, climatic models, DC resistivity, ground penetrating radar

NTS Mapsheet(s): 105F, 116B

Citation: Laxton, S. and Coates, J., 2011. Geophysical and borehole investigations of permafrost conditions associated with compromised infrastructure in Dawson and Ross River, Yukon. In: Yukon Exploration and Geology 2010, MacFarlane, K.E., Weston, L.H., and Relf, C. (eds.), Yukon Geological Survey, p. 135-148.

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