Global Positioning System Measurements of Crustal Motion in Antarctica

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Kamb Raymond 9527606 Abstract This award supports a project to establish a Global Positioning System geodetic network in the Transantarctic Mountains of Antarctica to measure vertical and horizontal crustal velocities. The vertical crustal velocities measured by GPS reflect the viscoelastic response of the solid Earth to Antarctic deglaciation. Data from this GPS network will be used to test models of late Pleistocene-early Holocene versus late Holocene deglaciation of Antarctica. These data will also constrain the length of time over which the Antarctic ice sheet disintegrated, and the distribution of the peak glacial load. A mid-Holocene deglaciation model produces a predicted uplift pattern in the vicinity of the Transantarctic Mountains that can be measured by high-precision GPS geodetic measurements within a time span of four years. Horizontal deformation induced by rebound will also be measured. These data will also help constrain present-day changes in Antarctic ice mass by monitoring the elastic deformation of the lithosphere resulting from ongoing glacial loading and unloading. The lithospheric response to ongoing ice mass changes is predicted to be an order of magnitude less than the viscoelastic response to late-Pleistocene-Holocene deglaciation. Tectonic uplift rates are also predicted to be very small compared to the predicted rebound signal for this region. Baselines across faults in the Transantarctics may capture co-seismic motion if an earthquake were to occur, or aseismic slip. The first year of the project will be spent in technology development for, and a proof-of-concept demonstration of, a prototype autonomous GPS station (AGS) under joint funding with JPL. This prototype station will be powered by solar panels and will collect data continuously during the deployment period. Data transmission via long-range Radio Frequency (RF) transceivers acting as modems will also be tested. The prototype station will be modified as neede d to implement a reliable, operational network of four autonomous GPS stations in the following year of the project, contingetn upon joint funding by NASA. The AGS network will send daily data reports McMurdo. The network will be a permanent installation that will continue to monitor motion in the region beyond the term of this project. Advanced processing techniques will be employed to increase the accuracy of the crustal velocity measurements, especially for the vertical component. These include orbit modeling, troposphere correction, ionosphere correction, and extraction of annual and seasonal solid Earth and ocean tidal signals.