Potential of Ground-Penetrating Radar for Imaging Active Layer and Ice Wedges in Permafrost Areas

Ice wedges are prominent phenomena of permafrost landscapes. These ice bodies typically build a characteristic polygonal micro topography, thus determining indirectly the distribution of moisture, vegetation, and elements within the seasonally unfrozen active layer. However, the existence of ice bodies in the subsurface is not always delineable based on surface data. Furthermore, the increased potential of subsidence poses a hazard to any infrastructure nearby in case of a temperature increase. Also, the identification of hidden ice bodies is relevant for scientific field work and drilling. Ground-penetrating radar has been proven to be a suitable geophysical tool for imaging sediments of the active layer at high resolution and determining the location of ice wedges in a non-invasive manner. However, the success of imaging based on widely used acquisition strategies (common-offset geometry, 2D data acquisition and processing flow) remains limited, mainly because of heterogeneities and complexity of ice bodies shapes. We examine the influence of subsurface heterogeneity and ice wedge geometry on imaging these structures, based on synthetic data for a 2D polygon scenario of successively increasing complexity. Subsequently, we apply our interpretation strategies for identifying ice wedges to field data from Siberia.