GAMSEIS Project Summary

This award, provided by the Antarctic Earth Sciences Program of the Office of Polar Programs, supports a seismological study of the Gamburtsev Subglacial Mountains (GSM), a Texas-sized mountain range buried beneath the ice sheets of East Antarctica. The project will perform a passive seismic experiment deploying twenty-three seismic stations over the GSM to characterize the structure of the crust and upper mantle, and determine the processes driving uplift. The outcomes will also offer constraints on the terrestrial heat flux, a key variable in modeling ice sheet formation and behavior.

Virtually unexplored, the GSM represents the largest unstudied area of crustal uplift on earth. As well, the region is the starting point for growth of the Antarctic ice sheets. Because of these outstanding questions, the GSM has been identified by the international Antarctic science community as a research focus for the International Polar Year (2007-2009). In addition to this seismic experiment, NSF is also supporting an aerogeophysical survey of the GSM; GAMBIT.

To examine details of the crust and upper mantle structure across the GSM, this passive seismic experiment is comprised of three elements: (1) A 900 km linear array of 12 broadband seismic stations extending across the GSM (array 1). (2) An intersecting 550 km linear array of 7 broadband seismic stations crossing the GSM at an angle of ~115 degrees to array 1 (array 2). (3) An additional non-linear array of 8 stations to provide improved 3-D resolution (Array 3).

This experiment will be conducted over a two-year period, to allow sufficient data collection from naturally occurring earthquakes, and will begin in December 2007. Airborne surveys to collect surface elevation, ice thickness, gravity, and magnetic data will be completed in support of this work under the GAMBIT project. Data will be analyzed using a variety of proven modeling techniques, including body and surface wave tomography, receiver function inversion, and shear wave splitting analysis. The results of these analyses will be maps of the variation in crustal thickness, upper mantle structure, anisotropy, and mantle discontinuity topography across the GSM. These results will provide a solid foundation for understanding the geodynamics of the Antarctic continent.

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