Seismic and radar investigations of Fourcade Glacier on King George Island, Antarctica

• Published in: Polar research Vol. 29; no. 3; pp. 298 - 310
• Main Authors: Young Kim, Ki, Lee, Joohan, Ho Hong, Myung, Kuk Hong, Jong, Keun Jin, Young, Shon, Howong
• Format: Journal Article
• Language: English
• Published: Routledge 01.01.2010
• Subjects: Bulk density; cold/warm ice interfaces; elastic properties; fracture; radar; seismic
• ISSN: 1751-8369; 1751-8369
• DOI: 10.3402/polar.v29i3.6082

To determine P- and S-wave velocities, elastic properties and subglacial topography of the polythermal Fourcade Glacier, surface seismic and radar surveys were conducted along a 470-m profile in November 2006. P- and S-wave velocity structures were determined by travel-time tomography and inversion of Rayleigh wave dispersion curves, respectively. The average P- and S-wave velocities of ice are 3466 and 1839 m s -1 , respectively. Radar velocities were obtained by migration velocity analysis of 112 diffraction events. An estimate of 920 kg m -3 for the bulk density of wet ice corresponds to water contents of 5.1 and 3.2%, which were derived from the average P-wave and radar velocities, respectively. Using this density and the average P- and S-wave velocities, we estimate that the corresponding incompressibility and rigidity of the ice are 6.925 and 3.119 GPa, respectively. Synergistic interpretation of the radar profile and P- and S-wave velocities indicates the presence of a fracture zone above a subglacial high. Here, the P- and S-wave velocities are approximately 5 and 3% less than in the ice above a subglacial valley, respectively. The S-wave velocities indicate that warmer and less rigid ice underlies 10-15 m of colder ice near the surface of the glacier. Such layering is characteristic of polythermal glaciers. As a relatively simple non-invasive approach, integration of P-wave tomography, Rayleigh wave inversion and ground-towed radar is effective for various glaciological studies, including the elastic properties of englacial and subglacial materials, cold/warm ice interfaces, topography of a glacier bed and location of fracture zones.