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

Authors: Kim, Ki Young; Lee, Joohan¹; Hong, Myung Ho¹; Hong, Jong Kuk¹; Jin, Young Keun¹; Shon, Howong²

Source: Polar Research, Volume 29, Number 3, December 2010 , pp. 298-310(13)

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Abstract:

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.

Keywords: Bulk density; cold/warm ice interfaces; elastic properties; fracture; seismic; radar

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1751-8369.2010.00174.x

Affiliations: 1: Korea Polar Research Institute, PO Box 32, Incheon 406-840, Korea 2: Department of Civil, Environmental and Railroad Engineering, Pai Chai University, Daejon 302-735, Korea

Publication date: 2010-12-01

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

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