This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

This tile contains all multibeam data held by Geoscience Australia on August 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.

A bathymetric grid of the South Tasman Rise Region (Longitudes 138° E - 158° E, Latitudes 38° S - 54° S) is produced. In doing so, the individual datasets used have been closely examined and any deficiencies noted for further follow up or have been rectified immediately and the changes documented. These datasets include modern multibeam data, coastline data obtained from georeferenced SPOT imagery, hydrographic quality data, echosounder data from research vessels and satellite derived bathymetric data. A hierarchical system was employed whereby the best and most extensive datasets were gridded first and applied as a mask to the next best dataset. A new masking grid would be formed from these datasets to pass non-overlapping data in the next best dataset. This procedure was employed until finally the satellite data were masked. All the various levels of masked data were then brought together by the gridding algorithm (Intrepid - Desmond Fitzgerald Associates) and an ERMapper format grid produced. A grid cell size of 0.00225° (nominal 250m) was used with many iterations of minimum curvature gridding and several passes of smoothing. The final grid is available in ERMapper, ArcInfo and ASCII xyz formats

The Geophysical Processing and Data Access (GPDA) project at Geoscience Australia has undertaken a programme of collating, editing and cataloguing all bathymetry data in the Australian Region. For convenience this region has been loosely defined as extending from 5CS to 80CS and 45CE to 180CE. The contents of the Bathymetric Database consists of four datatypes: - Multibeam Echosounder Data (including LADS) - Singlebeam Echosounder Data - Depths from the digitisation of pre-existing maps - "Depths" derived from remote sensing techniques (and produced grids) The dataset described by this metadata record is the Digitised Bathymetric Maps Dataset. The history of this dataset is somewhat convoluted as the digitising has been conducted by a number of organisations over a number of years using a variety of approaches. Essentially the dataset consists of any bathymetric data that were acquired by GA as the result of digitising a paper based map (or its electronic image). The types of maps that have been digitised include - AHS Fairsheets - AHS/Admiralty and IHO Charts (supplied by AHS) - NATMAP Bathymetric Series Maps (supplied by AHS) - State government Department of Works Maps - Miscellaneous maps produced by other organisations The data digitised by the AHS are supplied to GA in AHS Hydrographic Transfer Format (.htf). This ASCII based format has excellent metadata header records and a uniform organisation of the depth data, making them ideal for incorporation into a relational database. In addition the AHS have supplied Geotif images of the original maps (Fairsheets and Charts) that were used to produce the .htf files as well as ESRI Shapefiles that show the data extent and metadata for each of the original maps. These form an additional layer of metadata which can be used to aid data discoverability and quality control. The other sources of digitised map data are much less in number and data volume and generally do not come with the ancillary information (metadata, images and Shapefiles). Where possible these extra information have been produced at GA to maintain consistency with the AHO datasets. As at April 2007, the numbers of digitised maps are 2200 in number.

No abstract available

In September and October of 2011 Geoscience Australia surveyed part of the offshore northern Perth Basin in order to map potential sites of natural hydrocarbon seepage. The primary objectives of the survey were to map the spatial distribution of seepage sites and characterise the nature of the seepage at these sites (gas vs oil, macroseepage vs microseepage; palaeo vs modern day seepage) on the basis of: acoustic signatures in the water column, shallow subsurface and on the seabed; geochemical signatures in rock and sediment samples and the water column; and biological signatures on the seabed. Areas of potential natural hydrocarbon seepage that were surveyed included proven (drilled) oil and gas accumulations, a breached structure, undrilled hydrocarbon prospects, and areas with potential signatures of fluid seepage identified in seismic, satellite remote sensing and multibeam bathymetry data. Within each of these areas the survey acquired: water column measurements with the CTD; acoustic data with single- and multi-beam echosounders, sidescan sonar and sub-bottom profiler (sidescan not acquired in Area F as it was too deep in places); and sediment and biological samples with the Smith-McIntyre Grab. In addition, data were collected with a remotely operated vehicle (ROV), integrated hydrocarbon sensor array, and CO2 sensor in selected areas. Sampling with the gravity corer had limited success in many of the more shallow areas (A-E) due to the coarse sandy nature of the seabed sediments. This dataset comprises sediment oxygen demand measurements from the upper 2 cm of seafloor sediments.