Developing a practical and comprehensive approach to crustal deformation modelling in support of Australia’s time-dependent reference frame.
The Challenge
The Australian Geospatial Reference System (AGRS) supports accurate positioning and spatial information across Australia but cannot deliver 3-5 cm accurate positioning in regions that are undergoing deformation. Local and regional crustal deformation (changes to the Earth’s surface caused by tectonic forces) occurs due to natural and induced causes. In the context of maintaining a geodetic reference frame (coordinate system with a reference surface), it is vital that the incidence and impact of such deformation be captured and accounted for. The objective of this project is to develop, validate and demonstrate a workable solution to this problem. It is intended that this solution will become an intrinsic part of future datum maintenance, allowing users to be confident that deformation is not diminishing the accuracy of published coordinates nor undermining the overall quality of the reference frame.
Partners
The project partners are the Department of Finance, Services and Innovation, Spatial Services Division (DFSI), the State of Victoria through its Department of Environment, Land, Water and Planning (DELWP), Curtin University, the Commonwealth of Australia represented by Geoscience Australia, Land Information New Zealand, and Position++.
The Solution
As Australia moves toward the adoption of a time-dependent geodetic reference frame, and New Zealand looks to improve the resolution of its existing deformation models, the question arises as to how localised crustal deformation can be captured and accounted for in the calculation and dissemination of coordinates. GNSS CORS networks and terrestrial measurement techniques alone are generally not sufficient for determining crustal motion on a national scale, as they rarely offer the needed spatial resolution. Remote sensing techniques (e.g., InSAR) emerge as a useful complement to more traditional geodetic methods for monitoring crustal change. InSAR provides continental coverage with high temporal frequency and high spatial resolution. The primary objectives of this project are to:
- Use InSAR to detect temporal crustal deformation optimally and reliably.
- Identify the technical limitations of InSAR and evaluate complementary techniques that will deliver an accurate and comprehensive 3D picture of the deformation field.
- Identify the best way to convert derived deformation into a crustal deformation model suited to the needs of reference frame maintenance.
- Produce and validate a prototype crustal deformation model for (part of) Victoria.
- Explore and demonstrate the application of the deformation model in the context of datum maintenance and the publication of time-dependent coordinates.
Objective 1 will leverage complementary work done by Geoscience Australia (GA) and Land Information New Zealand (LINZ) focussed on improving InSAR processing to derive temporal crustal deformation, and on the automated generation of InSAR data products for deformation modelling. Objectives 2-5 will build on and extend the outcomes of objective 1 through two inter-dependent streams of research.
Impact
Australia is not alone in its need to monitor 4D crustal deformation for the purposes of maintaining a national geodetic reference frame. New Zealand and Japan have experience in this domain on account of high levels of seismic activity. Scientists from both countries are planning a joint project to refine InSAR as a crustal monitoring tool and, specifically, to deal with processing artefacts such as the ionosphere and temporal de-correlation, and to evaluate and quantify model uncertainty.
By collaborating with the teams at GA and LINZ the present project has developed a novel, multi-radar solution which produces a deformation grid over a region around the Latrobe Valley in Victoria. This research was highly promising, producing a deformation grid that adequately accounted for deformation from existing geodetic surveys, and shows promise towards building a national deformation model.
Contact
To learn more, contact FrontierSI at contact@frontiersi.com.au or Project Manager, Phil Delaney, at pdelaney@frontiersi.com.au.
