Lord Howe Rise Marine Seismic Survey 2016 (GA-0354/ KR1605) Bathymetry grids

Brief description

This dataset contains bathymetry products from the Lord Howe Rise 2D Seismic Survey undertaken by Geoscience Australia (GA) and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) during the period from 17 March to 16 May 2016 onboard the RV Kairei (Survey KR1605). The Lord Howe Rise (LHR) is a submerged plateau that extends from southwest New Caledonia to the west of New Zealand. Much of the LHR lies within the Australian marine jurisdiction at water depths of 1000-3000m. The Commonwealth conducted a scientific seismic survey over the Lord Howe Rise in 2016 in collaboration with JAMSTEC. This collaboration contributes to a larger research proposal submitted to the International Ocean Discovery Program (IODP) that would provide the first deep stratigraphic record for the Cretaceous Eastern Gondwana Margin. The IODP proposal, if funded, is to drill a deep stratigraphic well to a depth of 2-3 km below the seabed, possibly in 2020. In order to select the drill sites, GA and JAMSTEC are conducting site assessments that involve a seismic survey in 2016 and a geotechnical survey in 2017. Multibeam bathymetry data were acquired during the survey covering an area of 62,360 km2. Eight bathymetry grids of 50 to 80m resolution were produced using the shipborne 12 KHz sonar system.

This dataset is not to be used for navigational purposes.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: The Lord Howe Rise (LHR) 2D Seismic Survey, GA-0354/ KR1605 was acquired by Geoscience Australia on board the RV Kairei from the 17 March to 16 May 2016. The chief scientist on board was Dr Shuichi Kodaira (JAMSTEC) and Dr Scott Nichol (GA). The bathymetry dataset was acquired by JAMSTEC on board the RV Kairei and processed in the office by Michele Spinoccia, using CARIS HIPS & SIPS ver. 7.1.2. 1. First a vessel configuration file was created where the co-ordinates of the motion sensor and DGPS antenna and patch test offsets were recorded. 2. A new project was then created and the vessel configuration file was attached to the project file. 3. The raw swath sonar data, in raw.all format, for each line was then imported into the project and the vessel information assigned to the data. 4. The motion sensor, DGPS and heading data were then cleaned using a filter that averaged adjacent data to remove artefacts. 5. Different sound velocity profiles data for each block were attached to the corresponding raw swath sonar data files to correct the depths for changes in the speed of sound through the water column. 6. Then a new blank field area was defined that specified the geographic area of study and the co-ordinate system used. The co-ordinates for the study areas were WGS84 UTM-56S, 57S and 48S. 7. The data was cleaned by applying several filters that removed any remaining spikes in the bathymetry data using user defined threshold values. A visual inspection of the data for each line was then undertaken where artefacts and noisy data not removed by the filtering process were removed manually using Swath and subset editors modules of the Caris HIPS/SIPS software. 8. All the data for each bathymetric, motion sensor, DGPS, heading, tide and sound velocity profile data were merged to produce the final processed data file. A weighted grid of the processed data was then created for each Block. In GA the tide was applied to the grid to correct for tidal variations and velocity corrections were performed to correct for different artefacts and mismatches. 9. The processed data was finally exported as grids soundings or false coloured images for presentation and reporting and as final processed data in ASCII XYZ as well as geotif formats of 50, 70 and 80m resolution. - Vertical Datum: MSL - Horizontal Datum: WGS84 UTM Zones 56, 57 and 58S.