Permafrost Investigations Below The Marine Limit At Nain, Nunatsiavut, Canada

Discontinuous permafrost is a challenge for development in the coastal communities of Nunatsiavut, Labrador, northeast Canada, where local high relief limits suitable terrain for construction. These issues are particularly pronounced in Nain, the largest and northernmost community in Nunatsiavut, which is undergoing rapid population growth and expansion. In this study, DC electrical resistivity tomography was combined with geotechnical borehole records and in situ field data to evaluate the distribution of permafrost at four sites in the lowest parts of the community. Permafrost was identified in at least six of the seven geophysical transects, including beneath culturally critical community infrastructure. A supra-permafrost talik was imaged beneath a convenience store that has experienced extreme differential subsidence, demonstrating that excess ice exists in some of the region’s frozen sediments. The presence of permafrost near the shoreline likely reflects ground cooling due to wind-scouring of snow at the exposed sites and the thermal impact of frost-susceptible sediments. Despite uncertainties in geophysical interpretation due to local site disturbance and coarse near-surface fill at some sites, these results have important implications for future development in this northern coastal community.