Transient hydrology-induced elastic deformation and land subsidence in Australia constrained by contemporary geodetic measurements

Abstract

Earth's lithospheric deformation in response to geophysical and climatic processes manifests as a wide range of spatio-temporal elastic/viscoelastic deformation, including seismic and tectonic motion, mantle flow, and climate-induced hydrologic-cyrospheric-atmospheric mass transports. We use increasingly accurate contemporary geodetic measurements, including those from GPS, Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GFO) missions, to quantify the competing processes of the hydrological cycle and geodynamics within the Australian continental lithosphere over the last two decades, 2002 to 2020. Observed precipitation and temperature anomalies reveal that anthropogenic climate change may have exerted significant impact on the terrestrial water storage (TWS) evolution in Australia, as evidenced by anomalous fluctuation during the 2010-2012 El Niño Southern Oscillation (ENSO) events. In particular, enhanced TWS inferred from the geodetic observations is shown to be highly correlated with increased precipitation during the 2010-2012 La Niña event. The GPS observed vertical land motion cannot be completely explained by the elastic deformation induced by surface water storage variations across Australia, nor by the Glacial Isostatic Adjustment (GIA) geophysical process. We suggest that the geodetic-observed land subsidence of Australia at high spatial scales could be related to anthropogenic aquifer groundwater depletion, while the long wavelength signals may be associated with reference frame error and then tectonic deformation.