AGSO Cruise Report: Cruise 210 : The "Sojourn 7" Swath-mapping Cruise of R.V. Melville off Eastern Tasmania and in the Gippsland Basin

From 10 to 17 April 1997, the Australian Geological Survey Organisation (AGSO) chartered the 85 m Research Vessel Melville from Scripps Institution of Oceanography on a cooperative scientific basis, to map the sea bed east and northeast of Tasmania including the deep water part of the Gippsland Basin. The vessel was equipped with the SeaBeam 2000 multibeam sonar system, capable of swath-mapping the morphology and roughness of the sea bed in a swath 3.5 times as wide as the water depth. The central beam gave a 12 kHz bathymetric profile. Other equipment employed included a magnetometer and gravity meter. Navigation, by military standard GPS using the P code, had an accuracy of about 5 m. Detailed ship's tracks for the survey, from south to north, are shown in Figures 2-5.

The aims of the cruise were to determine the morphology and sea bed character of selected areas, to aid in tectonic, basin and sedimentological studies, to aid the fishing industry, and to provide critical information for future seismic profiling and geological sampling. Satellite gravity images, and sparse bathymetric and seismic profiles, were used to plan the survey.