Do crustal deformations observed by GPS in Tierra del Fuego (Argentina) reflect glacial-isostatic adjustment?

A. RICHTER; L. MENDOZA; J. L. HORMAECHEA; R. PERDOMO; D. DEL COGLIANO; M. FRITSCHE; R. DIETRICH

Valdivia

Conferencia; International Glaciological Conference VICC 2010 "Ice and Climate Change: A View from the South"; 2010

Centro de Estudios Científicos

Tierra del Fuego, the southernmost part of South America, hasrepeatedly been glaciated during the Pleistocene/Late Pliocene.According to geological and geomorphological evidence, importantice lobes extended then from Cordillera Darwin far into the eas-tern parts of the main island. Such changing ice masses act as asurface load producing a long-lasting visco-elastic deformation ofthe earth’s crust. In formerly glaciated regions the ongoing isosta-tic crustal response to the ice load changes since the Last GlacialMaximum has been detected by geodetic GPS (Global PositioningSystem) measurements. A regional geodetic GPS network hasbeen established in the Argentine part of Tierra del Fuego and re-peatedly observed since 1993. Based on these observations 3Dsite velocities have been determined for 30 sites. In this work weaddress the question if the observed vertical velocity componentscan be attributed to ice-load induced effects. In this particular region,the possible superimposition of crustal deformations due to tectonicprocesses associated with the active transform boundary betweenthe South American and Scotia tectonic plates poses a specialchallenge for the separation of glacial-isostatic signals. However,geodetic observations of glacial-isostatic effects could potentia-lly provide valuable constraints for the regional ice-load history.