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 EGGS database contains point depths to chronostratigraphic surfaces obtained from boreholes and four magnetic modelling methods. In regards to the depths obtained from inclined boreholes there are uncertainties on their measurement of the true vertical depths. These are currently being looked into and would be resolved in due course. Future development will include AEM, reflection seismic, MT and passive seismic. A Web Service will allow the public to download this data and will be accessed through the EFTF (Exploring for the Future) web portal.

The Bureau of Mineral Resources has again'extended its geophysical programme in the search for oil to the continental shelf area of Australia by carrying out a combined gravity, and seismic survey in the Timor Sea/Joseph Bonaparte Gulf area of northwest Australia. The survey investigated the capabilities of the surface marine gravity meter for reconnaissance gravitywork at sea, and the penetration and quality of seismic reflections obtainable using a spark discharge source consisting of an array of electrodes. The possibility of operating the two methods simultaneously was also investigated. The seismic reflection sections recorded were much better than expected, with good-quality reflections being recorded to 1.6.sec. the gravity meter and seismic'equiPment were operated simultaneously at boat speeds of 8 to 9 miles per hour. The-seismic results have shown that a large Permian and Mesozoic sedimentary basin exists in the Joseph Bonaparte Gulf and extends to the north and north-west into the Timor Sea. It is an offshore extension of the Bonaparte Gulf Basin, and contains at least 10,000 feet of post-Permian sediments. .Although the trends of the gravity anomalies agree with the general shape of the basin as defined by the seismic results, a large positive anomaly occupies the central deep part of the basinand does not seem to be related to basement relief.

At the request of West Australian Petroleum Pty. Ltd. and the Department of Mines, Western Australia, the Bureau carried out a seismic velocity survey in Rough Range No.1 Well, with the object of obtaining velocity distribution data for use in the interpretation of results of seismic refraction surveys in the area. Twenty-two shots were fired from a shot point about 1,000 feet from the well. Geophone depths in the welI ranged from 2,000 feet to 14,000 feet, usually at intervals of 500 feet, but the intervals were varied at points where there was a significant change in the stratigraphy. Recordings from 16 of the shots were used in the calculations. Results indicated that, as would be expected, the hard crystalline limestone which comprises the top 700 feet of section has a much higher velocity than the clastic limestones which underlie it. An abrupt velocity change from 7,100 ft/sec. to 12,600 ft/sec. at 3,250 feet corresponds approximately with the change from Windalia Radiolarite to Muderong shale, and also with a density change from 2.1 to 2.4. A second major velocity change from 12,600 ft/sec. to 16,500 ft/sec. at 6,800 feet also corresponds approximately with a density change from 2.5 to 2.7. An abnormal increase in velocity recorded at about 9,000 feet must be considered as very doubtful and velocities at this depth have been averaged.

Ice thickness measurements were made in 1961 by seismic methods on a line southward from S-2, a glaciological station 50 miles east-south-east of Wilkes Base, Antarctica. The traverse constituted the first year's work of a three-year programme. The results showed that the rock underlying the ice dips below sea level at a point between 20 and 40 miles south of S-2. It remains below sea level at all the locations occupied to the south, as far as 280 miles south of S-2, where the rock surface is again above sea level. The main feature is a valley disclosed in the rock formation between 40 and 80 miles south of S-2. Midway between these two points the rock lies at approximately 7500 ft below sea level. The positions of the Totten Glacier and the John Quincy Adams Glacier suggest that the valley may have been responsible for their formation.

The Bureau of Mineral Resources has carried out two large scale reconnaissance marine geophysical surveys in the Joseph Bonaparte Gulf and Timor Sea areas in 1965 and 19670 It is proposed to continue this geophysical reconnaissance to the south over the northwest continental shelf from Ashmore reef to Barrow Island. 16 000 line miles should be covered in 3 months on mainly east-west lines 9 nautical miles apart. The boat speed will be about 10 knots. The survey will be done by Ray Geophysics (Australia) Pty Ltd under contract.

At the request of the Australian Atomic Energy Commission, the Bureau of Mineral Resources, Geology & Geophysics conducted a seismic refraction survey on the site chosen for construction of a nuclear power station. The purpose of the survey was to determine the foundation conditions at the site and the properties of the rocks in relation to excavation methods and support of the proposed structures. The bedrock of the area consists of Permian sandstone (Jervis Bay Sandstone) overlain in places by unconsolidated Quaternary beach and dune sands. During the seismic work it was found that the sandstone beds have a relatively wide range of seismic velocities; often a higher-velocity bed overlies a lower-velocity bed, and this makes seismic refraction work difficult and less accurate. This is confirmed by laboratory measurements of seismic velocities on drill cores. Thin beds of higher- and lower-velocity sandstones occur, some too thin to be resolved by the seismic method. The seismic profiles presented must be considered bearing in mind these difficulties, Haterial sufficiently consolidated for foundations is shallow, and the seismic velocities indicate that some blasting will be necessary to excavate to the desired depth of 10 feet above mean high water level.

In November 1964, the Bureau of Mineral Resources made a brief experimental seismic survey near Cockroach Wdterhole in the centre of the Tobermory 1:250,000 map area, Northern Territory. This survey was designed as part of a more extensive reconnaissance seismic survey to be made in 1964 and 1965 on areas of outcropping Lower Palaeozoic rocks in the southern part of the Georgina Basln. In this initial part of the survey a shortial profile was shot using a simple recording technique and noise tests and tests of various shot and geophone arrangements were carried out. It was established that, despite diffibult drilling conditions and the prevalence of random, high frequency noise, a suitable seismic technique for reconnaissance in this area, which it was hoped was representative of a very extensive region, could be developed.

<p>2D seismic reflection data were acquired in the South Gippsland region of Victoria in June-July 2015. The project was a collaboration between the Geological Survey of Victoria (GSV) and Geoscience Australia (GA). The purpose of the survey was to gain an understanding of the geometry and internal structure of the Cretaceous Strzelecki Group and the underlying Palaeozoic basement of the Melbourne Zone. <p>Two hundred and three km of deep crustal reflection data were collected for the South Gippsland seismic survey along four transects 15GA-SG1, 15GA-SG2, 15GA-SG3 and 15GA-SG4. The data processing is being undertaken by a contractor on behalf of GA and GSV and is expected to be released in March 2016. <p>Raw data are available on request from clientservices@ga.gov.au

Seismic refraction velocities were measured in the Archaean or crystalline basement rocks at Mount Davies (SA) and Giles (WA) where the rocks are near the surface. Refraction velocities were measured in the Proterozoic outcrops of the Rawlinson Range and Lake Hopkins. Refraction velocities were measured in the Palaeozoic and Mesozoic rocks at Lake Christopher, and in the Mesozoic rocks at Iragana Turnoff. Those velocities were used as a basis for a suggested correlation between refractors recorded at traverses between Signpost and Mount Beadell. Reflection tecniques, as tried 9 yielded fair reflections at Mount Beadell, and doubtful reflection alignments at trig. point NMF 19. It is likely that the sedimentary basin shows an increasing thickness of sediments from Signpost to Mount Beadell, At Mount Beadoll there is at least 6000 ft of apparently post-Proterozoic sediments. The thickness and degree of metamorphism of Proterozoic ratio below this have not been determined. Present evidence suggests an area of uplift under Lake Breaden.