3D time-lapse imaging of polygonal patterned ground in the McMurdo dry valleys of Antarctica
We surveyed four sets of polygons at 0.5 m line spacing using 100 and 200 MHz antennas for 3D GPR imaging at two field locations in the McMurdo Dry Valleys of Antarctica, one in Victoria Valley and the other in Beacon Valley. The aim was to use 3D GPR and time-lapse 3D GPR to resolve subsurface structure and PPG process activity over the thaw season of polygonal patterned ground (PPG) in Antarctica. We applied migration and topographic corrections to the data sets before collating the data into 3D cubes. The subsurface structure can be analyzed using the processed profiles and resulting 3D data cubes. Signal was received down to 12 m (200 MHz) and 20 m (100 MHz) depth. Variations in salt concentrations, soil horizons and crack penetration may be interpreted using these data sets. The time-lapse images from Victoria Valley show reductions in signal through the season provisionally identified with changing quantities of free water and salts associated with PPG activity. The results show that 3D GPR allows the collection of valuable information about the subsurface structure and processes of PPG and provides a way to monitor changes in these processes as climatic conditions evolve.