Geophysical characterization of permafrost terrain at Iqaluit International Airport, Nunavut

Iqaluit International Airport presently suffers from instabilities and subsidence along its runway, taxiways and apron. In particular, asphalt surfaces are significantly impacted by settlement and cracking. These instabilities may be related to permafrost, permafrost degradation and associated drainage conditions. Low induction number electromagnetic measurements along with galvanic and capacitive electrical resistivity surveys were performed over selected areas within the airport boundary and in the near vicinity to assist with permafrost characterization and to investigate active permafrost processes. Electrical resistivity images suggest distinct electrical signatures for different terrain units and sediment types, and for ice-rich material including ice wedges. Anomalous regions are identified that are coincident with localized settlement problems. Repeated resistivity maps reveal seasonal changes indicative of high unfrozen water content and freeze/thaw of groundwater beneath airport infrastructure in distinct regions related to surficial geology. Even with continuous permafrost and cold permafrost temperatures, the resistivity models reveal anomalously conductive material at depth that is not obviously correlated to mapped surficial sediments and that may represent thaw susceptible sediments or significant unfrozen water content. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.