We live on a dynamic planet. Observations from seismic and geodetic techniques as well as modelling approaches inform our understanding of the deformation of the Earth’s surface. Over recent decades horizontal site velocities from space geodetic techniques such as the Global Positioning System (GPS) have been used to study plate tectonic kinematics in global and regional settings.
Solid-earth deformation informs our understanding of the response of the earth system to climate and sea level change, surface mass transport, postglacial and present-day ice loading, tectonic motion, elastic and viscoelastic relaxation, resource extraction, and mantle convection. Geodetic time series are used to monitor the deformation of the solid Earth and its fluid envelope, but their robust interpretation depends entirely on the stability and accuracy of the underlying reference frame. For an accurate and stable reference frame, unbiased position estimates and velocities with realistic uncertainties are necessary to advance understanding in each of these application areas.
Several questions remain in interpreting geodetic time series of surface displacement which are relevant to understanding the long-term (decadal to millennial) vertical displacement of Australia:
To what extent can geodetic time series represent displacements beyond their data span? What is the appropriate model for this motion? How do short-period displacements or noise affect the ability to robustly estimate the model parameters? What is the characteristic of the noise in the context of the adopted model? Is the underlying geodetic reference frame sufficiently accurate to allow measurement at the accuracy required?
This presentation combines rigorous high-quality processing of GPS data with time series analysis, deformation modelling, and spatiotemporal filtering to explore how the Australian continent is moving and what that means for applications of precise positioning, including the stability and accuracy of the underlying reference frame.