Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

A set of recommendations for application of automated terrain correction of gravity anomalies in Australia. Recent improvements in position and elevation determinations due to Differential GPS have led to substantial improvements in the accuracy and precision of observed gravity data, and a general renaissance in the use of gravimetry in Australia. Increasingly, users of the data are specifying levels of precision in derived measurements such as the Bouguer Anomaly, that reflect only these positioning improvements without considering topographic effects on precision. The consequence has been that most gravity data routinely submitted to the National Gravity Database are Simple Bouguer Anomalies only, and contain a range of unquantifiable acquisition noise that degrades the quality of the overall dataset. This paper briefly describes the principles behind the terrain correction of observed gravity data, and outlines one method of rapidly calculating the value of a 'first pass' terrain correction for gravity values in Australia. This method makes use of the widely available 9 second Digital Elevation Model of Australia and the IntrepidTM geophysical software package developed jointly by the Australian Geological Survey Organisation and Des Fitzgerald & Associates. The assumptions and pitfalls behind this particular method are also described. A comparison between the Intrepid method and traditional Hammer-chart manual methods is described using a test dataset from northern Tasmania. The comparison shows that the IntrepidTM method is suitable for applying coarse corrections using the generally available DEM. However, the limitations of the DEM itself prevent use in extreme topographic situations, where a more detailed DEM is needed. Overall, in Australian conditions, the method should prove practical. Finally, test data are also provided on an ftp site to allow users to test their own terrain correction algorithms.

Flyer to be carried by GA officers while undertaking a building survey in the Brisbane Central Business District

The powerpoint presentations given by specific AGSO authors at the 2000 AAPG International Conference and Exhibition, Energy for the New Millennium, 15-18 October 2000, Bali, Indonesia. Contents: Edwards_Bali.ppt - Paper presented by Dianne Edwards: Edwards, D.S., Kennard, J.M., Preston, J.C., Summons, R.E., Boreham, C.J. and Zumberge, J.E., "Geochemical characteristics of Mesozoic petroleum systems in the Bonaparte Basin, northwestern Australia". Abstracts volume A24 (NOTE: Oil family dendrograms are for company in-house use only) Kennard_Bali.ppt Paper presented by John Kennard: Kennard, J.M., Edwards, D.S., Ruble, T.E., Boreham, C.J., Summons, R.E., Cooper, T.G., King, M.R. and Lisk, M., "Evidence for a Permian petroleum system in the Timor Sea Region, northwestern Australia". Abstracts volume A45.

Why do cliffs and overhangs drop rocks? Cliffs are formed and wear away by erosion. Water and wind blast the rock with solid particles, waves pound the cliffs, and water dissolves minerals in the rocks. As the cliffs wear away, they form overhangs that weaken, break and fall suddenly. Rocks can also fall off cliffs if water or tree roots enter cracks behind the cliff face. On 27 September 1996, people were sheltering under an overhang in a limestone cliff near Gracetown, Western Australia. The overhang and part of the cliff behind collapsed, and about 2500 tonne of rock and sand fell. Nine people were killed and three others injured. The collapse was partly attributed to the rock absorbing water and becoming heavier. Remember, it is natural for rocks to fall off cliffs!

One of Australia's most serious natural disasters occurred when an earthquake shook Newcastle in New South Wales, leaving 13 people dead and injuring more than 160. The damage bill has been estimated at around A$4 billion dollars, including an insured loss of over A$1 billion. All the result of just a few seconds of earthquake ground shaking at 10:27am on 28 December 1989 (McCue and others, 1990). The consequences of this moderate earthquake to Newcastle (Pop. 300 000), an industrial city on Australia's east coast, could so easily have been avoided with the hindsight of history and the application of relatively inexpensive earthquake engineering principles.

OBS experiments in Australia have been limited so far, with the only data set collected by Geoscience Australia in 1995-1996 on a number of coincident reflection/refraction seismic transects across the NW Australian Margin. In 2013 Australia, for the first time in its history, will obtain a National Pool of ocean-bottom seismographs (OBS) suitable for multi-scale experiments at sea and for onshore-offshore combined observations. Twenty broadband OBS were purchased for short and long term deployment (up to 12 months) to a maximum water depth of 6 km. The instruments will be made available to Australian researchers via ANSIR, with only the costs of mobilization and deployment to be met. It is anticipated that the OBS facility will greatly enhance the research capabilities of Australian scientists in the area of Earth imaging, off-shore exploration and natural hazard assessment.

Fundamental to an understandng and management of risk is reliable information about what is exposed to natural hazards and threats. Exposure includes people, buildings, business activity and critical infrastructure. Geoscience Australia (GA) has undertaken the development of the National Exposure Information System (NEXIS) which is a significant national capability to provide reliable and up-to-date information for decision makers. NEXIS collects, collates, manages and provides the information required to assess community exposure, impacts and risk. Presently the capability consistently defines national residential and business exposure using a largely statistical approach with information aggregated at buildings level. The exposure information is derived from the best available datasets and includes a broad range of useful information fields. Progressively this information is transitioning to more specific information in collaboration with a range of data custodians. Furthermore, the capability is being extended to institutional buildings (schools, hospitals, government buildings, emergency assets etc.) and infrastructure assets. Alignment of future development to the needs of stakeholders is vital.