Detection of buried ice and sediment layers in permafrost using multi-frequency Ground Penetrating Radar: A case examination on Svalbard

Abstract

We use multi-frequency Ground Penetrating Radar (GPR) to detect and map buried relic glacier ice and sediments in permafrost. Old aerial photographs 1936–1990 are used to show the origin of a sediment covered ice body, and illustrate how it has been buried. Together with a newly exposed ice/sediment cliff, this serves as excellent ground truthing for the GPR data. Empirical GPR frequency dependent relations are established to quantify the loss of the signal power through the layer of sediment. The loss through ice is in comparison negligible. These relations indicate that the maximum ice pocket detection depth (for this sediment type), with the different GPR systems used, are 90, 150 and 200 ns for the 800, 500 and 200 MHz systems respectively. The electromagnetic (EM) wave velocities calculated from diffractions yield velocities ranging between 0.115–0.135 m/ns for the sediment and 0.15–0.17 m/ns for the ice. With the derived EM wave velocities, these Two-Way-Travel (TWT) times correspond to a depth of ∼ 6, 9 and 13 m respectively. This loss cannot be tested for the 200 and 500 MHz systems due to lack of such a deep sediment layer on top of the ice, but is consistent with the 800 MHz data.