Ground-penetrating radar images of near-surface glacial crevasses in Antarctica: a review and new data

Crevasses are among the most dangerous near-surface features of Antarctic glaciers. They are particularly hazardous when hidden crevasses covered by snow or ice and cannot be detected visually. Ground-penetrating radar (GPR) is one of the most effective methods for detecting such features and estimating their morphometric characteristics. This article presents a review of published GPR observations of glacier crevasses, numerical modeling results and field surveys from several Antarctic sites near the Russian Mirny, Progress, Novolazarevskaya, Russkaya stations, and in the vicinity of Bunger Oasis field base. Field studies were carried out using GPR systems with antenna frequencies ranging from 100 to 900 MHz, and synthetic GPR sections were calculated using gprMax software to interpret the results. The results show that GPR images of crevasses depend on medium, crevasse geometry, infill material, thickness of the snow bridge, antenna frequency, and orientation of the profile. Crevasses formed in meteoric ice typically produce distinct diffraction hyperbolas, whereas crevasses formed primarily in snow and firn appear as disrupted layering and zones of weakened reflections. Wide crevasses are characterized by two subvertical columns of diffracted waves and a low-amplitude zone between them. Water-filled crevasses produce high-amplitude reflections and multiple reverberations due to strong dielectric contrasts.