Electrical resistivity measurements in permafrost terrain at the Engineer Creek road cut, Fairbanks, Alaska

Abstract

Electrical resistivity measurements were made at a highway road cut in permafrost terrain using 3 methods (galvanic resistivity, magnetic induction and surface impedance). The purpose of these measurements was to attempt to detect the presence of excess ice (segregated ice and massive ice) in permafrost and to compare various resistivity methods for this purpose. A road cut was used to determine the subsurface soil and ice conditions for interpretation of the measurements. Apparent resistivity values measured by galvanic resistivity, magnetic induction and surface impedance methods increased substantially where the permafrost contained segregated and/or massive ice. These changes in resistivity reflected the location and horizontal extent of segregated and massive ice in the road cut although it was not possible to distinguish segregated ice from massive ice. Seasonal and spatial variations in resistivity suggest that the most favorable time to perform these measurements to detect segregated and massive ice in relatively warm permafrost consisting of fine-grained soils is in the Winter and Spring, when the active layer is frozen. The magnetic induction method is the fastest and simplest method to use under field conditions; however, certain field situations may require measurements with other methods.