Permafrost Ice Wedge Geometry Estimates from Ground Penetrating Radar Profiling

Abstract:

Permafrost ice wedges are found throughout terrestrial cryosphere, often comprising the dominant fraction of ground ice. This form of ground has important implications in a permafrost system because as the wedge ice, the inherent structural support given to the sediment is lost and subsidence and flooding occurs. The volume of ice found in wedges is poorly known because the wedge geometry is difficult to measure with direct methods; most estimates of wedge depth come from exposures at thermo-erosional features. Here we demonstrate the a novel interpretation of a well-known non-invasive ground penetrating radar (GPR) measurement that may be useful for measuring ice wedge depth. Using synthetic data and a field data examples, we detail the signal anomaly observed in the GPR record associated with ice wedges and demonstrate that a genetic algorithm (GA) inversion can be used to recover the wedge depth by optimizing the fit between measured and simulated radar cross section (RCS). Our results indicate that this optimization approach can recover wedge geometry even under noisy conditions.