From 1 - 10 / 76
  • The Bureau of Mineral Resources carried out a seismic survey of four months' duration in the Carpentaria Basin, North Queensland, in the second half of 1958. The survey showed that the Carpentaria Basin deepens gradually from the south, east, and west towards the southeastern corner of the Gulf of Carpentaria. The maximum thickness of sediments measured was about 1000 metres near Rutland Plains in the north of the survey area. It was found that gravity anomalies in the area do not correlate with basement relief.

  • On 30th March 1960, a seismic velocity survey was made in the A.A.O. Timbury Hills No. 2 bore, jointly by the Bureau of Mineral Resources and Associated Australian Oilfields N.L. The bore had been drilled to a depth of 4400 ft and was surveyed to a depth of 4304 ft below the rotary table. There remains a doubt whether the breaks recorded on the well geephone were, in fact, cable breaks, particularly between 2300 and 3305 ft below the rotary table. The interpretation has boon made with the belief that true breaks wore recorded. Average and interval velocities were computed and are acceptable geologically. Sandstones, particularly cemented ones, have Renerally higher velocities than shale. The average velocity of the Mesozoic sequence is about 9800 ft/sec. A velocity of 17,980 ft/sec was measured at the bottom of the bore and corresponds to the Timbury Hills Formation of unknown age. The Moolayember Shale has a low velocity calculated as 8360 ft/sec.

  • A seismic velocity survey of the APM Development Pty Limited No. 1 bore at Rosedale, Victoria, was made by the Geophysical Branch of the Bureau on the 3rd May 1960 using a TIC three-component well geophone. Measurements were taken with the geophone suspended in the well at selected intervals down to 5500 ft. It was apparent that signals reached the geophone by transmission along the cable by which it was suspended, and these interfered with the signals reaching the geophone along a path directly through the ground. This made interpretation difficult; however, by careful inspection of both the vertical and horizontal components of the signals received by the geophone at each depth, an interpretation has been made that yields a series of velocity/depth determinations. The average vertical velocity increases from 5000 ft/sec at the surface to 8930 ft/sec at a depth of 5500 ft. The average velocity in the Tertiary (0-2159 ft below datum) was computed to be 6420 ft/sec; the -werage velocity in the Mesozoic rocks penetrated (2159-5314 ft below datum) was 12,180 ft/sec. Two reflection spreads laid out and recorded in the vicinity of the bore showed the presence of reflectors at depths estimated to be in excess of 7700ft.

  • Between August and December 1960 a seismic party from the Bureau of Mineral Resources carried out a reconnaissance seismic survey, using reflection and refraction techniques, across the Murray Basin. Traverses were placed at selected localities at Carrathool, Hay, Maude, Balranald, Wentworth, Merbein, Lake Victoria, and Loxton. In general, the results show that the Basin, at least along the line of traverse, consists of essentially undisturbed sediments above a high-velocity basement. The thickness of Basin sediments ranges from about 900 ft at Carrathool to 2200 ft at Lake Victoria and Merbein. Most of the sediments are of Tertiary age, with Mesozoic at Loxton and Wentworth and perhaps at other traverses in the western part of the Basin. The seismic velocity in the sediments has a typical value of about 6000 to 7000 ft/sec, while the velocity in the basement ranges from 15,750 ft/sec (at Hay) up to 20,000 ft/sec (at Lake Victoria). The geological nature of basement is not known, but it is considered that it definitely marks the floor of the Tertiary (or Tertiary - Mesozoic) basin. Refraction velocities alone are of doubtful value in identifying the floor, as it is known that crystalline basement, metamorphosed sediments, or unmetamorphosed sediments such as limestone, may have velocities within this range.

  • Between February and April 1961 the Bureau of Mineral Resources, Geology and Geophysics made a seismic survey in the Rosedale area of the Latrobe Valley, partly at the request of the State Electricity Commission of Victoria to provide more information about the brown coal measures in this area, and partly in order to test the Bureau's latest seismic recording equipment. One traverse, combining both reflection and refraction profiling techniques, was run south from the A.P.M. No.1 bore at Rosedale as far as Merrimans Creek, and a second traverse was run west from the bore as far as Toongabbie. Results show that the maximum thickness of the Tertiary sequence is about 3000 ft and that it thins gradually to 1000 ft at Toongabbie and rapidly to about 750 ft on the Baragwanath Anticline. It is shown that early Tertiary deposits were laid over the whole area but have been uplifted and partly eroded in late Tertiary or post-Tertiary times in the Toongabbie and Baragwanath areas, but the main syncline sank and accumulated thick Tertiary sediments. Results show alao that on the northern flank of the Baragwanath Anticline where crossed by the seismic lines the Tertiary and Jurassic sediments are steeply folded but not necessarily faulted. No positive information was obtained below 4500 ft but long refraction shots suggest that a high-velocity basement does not exist at a depth less than 12,000 ft.

  • Geoscience Australia in collaboration with the Geological Survey of NSW acquired the Yathong Trough Deep Crustal Seismic Survey in 2013. The survey involved the acquisition of seismic reflection and gravity data along two traverses, 13GA-YT1 (98km) and 13GA-YT2 (132km) near Hillston, NSW. The purpose of the survey was to acquire new data to better understand the regional geology and major structured of the Yathong Trough within the Darling Basin, NSW. Funding was from the Geological Survey NSW through the New Frontiers Initative. Raw data for this survey are available on request from clientservices@ga.gov.au

  • We report four lessons from experience gained in applying the multiple-mode spatially-averaged coherency method (MMSPAC) at 25 sites in Newcastle (NSW) for the purpose of establishing shear-wave velocity profiles as part of an earthquake hazard study. The MMSPAC technique is logistically viable for use in urban and suburban areas, both on grass sports fields and parks, and on footpaths and roads. A set of seven earthquake-type recording systems and team of three personnel is sufficient to survey three sites per day. The uncertainties of local noise sources from adjacent road traffic or from service pipes contribute to loss of low-frequency SPAC data in a way which is difficult to predict in survey design. Coherencies between individual pairs of sensors should be studied as a quality-control measure with a view to excluding noise-affected sensors prior to interpretation; useful data can still be obtained at a site where one sensor is excluded. The combined use of both SPAC data and HVSR data in inversion and interpretation is a requirement in order to make effective use of low frequency data (typically 0.5 to 2 Hz at these sites) and thus resolve shear-wave velocities in basement rock below 20 to 50 m of soft transported sediments.

  • The Oaklands-Coorabin Coalfield in the Riverina Division of New South Wales has been known for many years. Seismic refraction tests were carried out on a number of sections to assist in the interpretation of the gravity results during July and Sepetember, 1949.

  • Geoscience Australia acquired the Canning Coastal Deep Crustal Seismic Survey in 2014. The survey involved the acquisition of seismic reflection and gravity data along two traverses, 14GA-CC1 (562km) and 14GA-CC2 (143km) between Port Hedland and Derby, WA. The purpose of the survey was to image the crustal architecture of the geology underlying the Canning Basin and its relationship to the boundaries between the crystalline hard rock areas of the North (Kimberley) and West Australian (Pilbara) cratons. As well as establishing the subsurface extent of the Canning Basin and the extent and nature of its sub-basins and troughs. The project was collaboration between the Geological Survey of Western Australia and Geoscience Australia with funding from the Western Australian Royalty for Regions Scheme. Raw data for this survey are available on request from clientservices@ga.gov.au

  • The preliminary investigation was made when the Bureaut s seismic party was held up by flooded rivers, while on its way t o Christmas Creek in May, 1954. Results show that the seismic aethod is applicable to the Broome area, and that a sedimentary section of the order of 12,500 feet exists. They further show that a syncline and anticline not known from the surface geology may possibly exist at depth.