Analysis of Antarctic Crustal Motion Using Remote Sensing and GPS Data: Applications to Ice Mass Change Studies

Tilted paleoshorelines and GPS data from the Dry Valleys and surrounding region of Victoria Land, Antarctica are analyzed. Paleoshorelines of proglacial lakes were mapped utilizing a multisensor approach, and tilts were derived from elevations along strandlines digitized from high-resolution airborne Light Detection and Ranging (LiDAR) digital elevation models (DEMs). Resulting tilts were combined with shoreline age data to determine long-term patterns of crustal deformation. Modern rates of horizontal crustal motion and crustal tilting were derived from GPS stations within the Transantarctic Mountain Deformation (TAMDEF) network and the Antarctic Network (ANET) component of the Polar Earth Observing Network (POLENET). Patterns of crustal motion observed from both GPS and paleoshoreline records are interpreted to document GIA-induced crustal deformation since the Last Glacial Maximum (LGM). A change in earth deformation pattern with time suggests that the weak earth profile beneath the study region permitted successive responses to multiple phases of ice mass change since the LGM. Shoreline tilt directions suggest ice unloading associated with Talos Dome in the northern Victoria Land and Wilkes Land sectors of East Antarctica. Unloading in this region is not represented in models of GIA for Antarctica, suggesting current GIA models underpredict ice mass loss and resultant rates of rebound for northern Victoria Land and Wilkes Land sectors of East Antarctica. Significantly, such an underprediction of GIA rebound rates indicates that estimates of East Antarctic ice mass balance derived from the Gravity Recovery and Climate Experiment (GRACE) satellite-based studies, which are strongly dependent on GIA model corrections, have underestimated ice mass loss from the East Antarctic ice sheet.