2005-2006 Field Season

THE WEST ANTARCTIC GPS NETWORK PROJECT

Beneath the thick carapace of ice covering Antarctica are active faults and volcanoes that, together with predicted motions of the Earth's major tectonic plates, provide evidence of the existence of a rift in the lithosphere of West Antarctica. The future behavior of the Antarctic ice cap and the corresponding effect on sea level is largely controlled by the behavior of the underlying lithosphere. The WAGN project uses the Global Positioning System (GPS), a precise satellite-based navigation system, to measure crustal motions of the bedrock underlying and surrounding the West Antarctic Ice Sheet (WAIS).

SCIENTIFIC OBJECTIVES

To study tectonic activity beneath the WAIS, scientists from The University of Texas Institute for Geophysics (UTIG), the Pacific GPS Facility at SOEST, and the Center for Earthquake Research and Information (CERI) at the University of Memphis are using blocks of solid rock that poke up through the Antarctic ice like islands in the sea as sites for GPS measurements. These features, which are called nunataks, move up or down, or from side to side, with the lithosphere. The scientists will make one set of GPS position measurements this austral summer (2002) at about 15 different sites, wait one to two years, and then re-measure the positions of the sites in order to determine the magnitude and rates of the vertical and horizontal motions of the underlying bedrock. By quantifying the tectonic movements of the bedrock underlying the WAIS, they will be able to make comparisons with plate tectonic models and provide a realistic background for understanding how the tectonic motions of West Antarctica might influence the behavior of the overlying ice sheet, an area of critical importance to global climate and, particularly, future changes in global sea level.

For more about the science, please visit NSF's award Web site.

IMPACT ON SEA LEVEL

If the ice sheets of West and East Antarctica melted and their volume was transferred completely to the ocean, sea level would rise by about 70 meters. The East Antarctic ice sheet, however, is stable and probably has not been smaller than present at any time during the past several hundred thousand years. The WAIS in contrast, is a marine ice sheet whose base lies well below sea level. If the WAIS were to become unstable and flow out to sea, although it would not immediately melt, it would still displace enough ocean water to cause sea level to rise five to six meters, which is about the level that sea level reached 125,000 years ago. This would have severe social and economic consequences for many low-lying coastal areas around the world.

EDUCATION AND TRAINING

This project is currently providing opportunities for graduate students Dana Caccamise and Hao Zhou (SOEST) to conduct research and to participate in the fieldwork each year in the austral summers, beginning in 2001-2002 and for several years thereafter. Dana and Hao, as well as other students, will be involved in processing the data and interpreting the results.

COLLABORATION

This GPS study represents a collaboration between Drs. Ian Dalziel and Fred Taylor of The University of Texas at Austin, Dr. Michael Bevis of the University of Hawaii and Dr. Robert Smalley of the University of Memphis. Funding is from the U.S. National Science Foundation's Office of Polar Programs.

RELEVANCE

Of all the possible aspects of global climate change, it is likely that a significant rise in global sea level would represent one of the greatest economic and social catastrophes. With the advent of new GPS technology and knowledge of numerous West Antarctic rock outcrops based on the vast field experience of Ian Dalziel, the WAGN team will be able to make measurements to quantify the motion of the West Antarctic crustal motion and to evaluate how these motions may influence the stability of the overlying ice sheet. This knowledge is critical for evaluating both the history and the future of the West Antarctic Ice Sheet.

Nunataks are part of the Earth's crust. The surficial glacier ice slowly flows around them towards the sea.

Locations of known active volcanoes in Antarctica and the approximate position of the West Antarctic Rift System.

Locations of the West Antarctic GPS sites and existing continuous GPS sites operated by other GPS projects in Antarctica. The WAGN project will add 15 new sites, and will also use data from other GPS stations on the Antarctic continent.

The WAGN team with the ski-equipped deHavilland Twin Otter aircraft they use to reach interior sites.