CREVASSE DETECTION IN GLACIERS OF SOUTHERN CHILE AND ANTARCTICA BY MEANS OF GROUND PENETRATING RADAR

Abstract

Detection of crevasses is critical for safe travelling on glaciers. Here we present the use of a Ground Penetrating Radar (GPR) for crevasse detection. Experiments were made in temperate ice on Glaciar Mocho, Volcán Mocho-Choshuenco, southern Chile (39°25'S) and in cold ice in East Antarctica (87°30'S). In southern Chile the radar was hand-carried 1.2 m in front of the operator who was walking over the glacier at a speed of ~0.5 m s -1 , while in Antarctica it was mounted on a 7 m-long rod in front of a tractor convoy travelling at a speed of ~2 m s -1 . In both geographical sites profiles were made perpendicularly to crevasses ranging in width from 0.1 m to 1.0 m. Buried crevasses clearly show as apexes of diffraction hyperbolae, which could be detected down to a depth of 15 m. Show as discontinuities in the firn stratigraphy which have a width equal to the crevasse width, and associated diffraction hyperbolae to each side of the crevasse. The GPR proved to be a valuable tool for detecting crevasses, allowing for a reaction time of ~9 s (equivalent to ~4.5 m on the ground) in the case of the hand-carried system and ~5 s (or ~10 m on the ground) for the tractor system.