Earth Imaging & Sounding
Building a picture of the subsurface
How do we see into the Australian continent? And what does it tell us?
Like an x-ray for humans, we scan the Earth— but with specialist geophysical equipment to build up a clear and rich picture of our entire continent’s subsurface, from a few meters to 100’s, even 1000’s of kilometres deep.
We collect new data where none are currently available, or have never been collected. These datasets are used in many research and natural resources exploration applications.
AuScope builds on existing national geophysical datasets, developed by Geoscience Australia, ANSIR and others, providing an increasingly clear and rich picture of the subsurface of our continent. Over the years, we have invested in:
An upgrade of existing passive seismic and magnetotelluric (MT) equipment to present state-of-the-art. This included the purchase of broadband seismic recorder systems based at the ANU, MT broadband systems based at University of Adelaide and the ANU, and MT low frequency systems based at the University of Adelaide.
The acquisition of ~250 line-km per annum of seismic (reflection and portable instrument) and MT imaging. The AuScope investment enables the university-based research community to have a seat at the proposed National GeoTransect planning table, and to use its 250 line-km contribution to leverage access to a much larger Earth Imaging dataset.
Operating and maintaining the instrumentation, and for coordinating and managing the AuScope National GeoTransect Program. These tasks include ensuring that the data / information from transects is processed, stored and managed appropriately, and in liaising with the AuScope Grid manager to ensure broad access and interoperability.
AuScope has invested in the Australian Seismological Reference Model (AuSREM), and fleets of seismometers & seismic data loggers, ocean bottom seismometers (OBS), and magnetotelluric (MT) field instruments.
What we’re working on
We are currently working on:
Collecting and processing national MT datasets at Adelaide University and Australian National University nodes; and
Loading national MT data into the AusPass portal.
Since 2006, we have renewed capacity for broad-band seismic recording by replacing the ANSIR equipment that was obsolete and no longer supported by the manufacturer; and, built up a national capacity for MT studies.
We have also invested in geotransects as a contribution to data infrastructure, as recommended in the 2003 National Strategic Plan for Geoscience. This has resulted in a major increase in the coverage of the continent through detailed full crustal reflection profiles, and had both scientific and economic importance.
Australia is a significant player in the International Seismology Community as it led deploying “rolling” arrays across the Australian continent starting in the early 1990s with the Skippy Project experiment. The majority of these seismic data were archived offline at ANU.
In mid-2018 we launched the beta version of the AusPass data centre, in which ~30 years worth of archived passive seismic data are now openly available through this portal.
Access to the portable seismic and MT equipment is through the submission of a short scientific proposal assessed by an Access Committee for scientific merit. We accept a regular stream of proposals for use of the component infrastructure is being received and requests frequently exceed the available capacity.
The large pool of short-period recorders reached the end of their working life and further investment through AuScope’s Australian Geophysical Observing System (AGOS) replaced this equipment. We purchased seismometers with a co-investment from ANU to be paired with the new low-power systems developed and built by the electronics workshop in ANU’s RSES.
The international trend in deployments of portable seismic instrumentation is to use large numbers of instruments with many cooperating institutions. Our Australian Earth Imaging community is small but very active, and is being challenged by this trend. The typical quantum used in current experiments supported by AuScope is 25 broad-band recorders with solar panels or 50 short-period recorders with internal batteries. These numbers represent what we can reasonably deploy.
More recently, new development in seismology, “large-N” arrays, use new nodal-type seismic instrumentation. Large-N refers to 1-2 orders of magnitude more instruments per experiment and nodal refers to the small (paint can size). This new technology is transforming how we acquire data and will end spatial aliasing, providing much higher resolution and a broad range of applications. These instruments can be utilised in quick deployment after a regional earthquake (aka RAMP studies), monitoring induced seismicity, and many other important scientific applications.
As well as supporting core seismic imaging work in Australia, the portable seismic instruments will become increasingly used in the surrounding regions (e.g. New Zealand and Indonesia) to help address fundamental issues such as seismic and tsunamigenic hazard. With these new endeavours, we require a more international and collaborative approach.
As. Prof. Meghan Miller
Australian National Uni
For more information on current and potential projects or accessing AuScope’s Earth Imaging and Sounding infrastructure component please get in touch with Meghan.
Dr. Graham Heinson