MH370: Bathymetric Survey
Geoscience Australia is applying specialist knowledge and capability in the search for missing flight MH370. This expertise proved critical in understanding the environment in which the search is operating.
Video: Mapping the deep ocean
The Joint Agency Coordination Centre (JACC) is the lead agency in the search for missing Malaysia Airlines Flight MH370, coordinating all Australian Government assistance and is responsible for whole-of-government information, including keeping the families of those onboard and the general public, informed of the progress of the search.
The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator and is leading the search operations for MH370.
Geoscience Australia provides advice, expertise and support to the ATSB in sea floor mapping (bathymetric survey) and the underwater search.
The search for MH370 includes a bathymetric survey, providing a detailed map of the sea floor topography of the search area; and an underwater search using scanning equipment or towed submersible vehicles. The information gained in the bathymetric survey is used to build a map of the sea floor in the search area, aiding navigation during the underwater search.
Bathymetric surveys were conducted from May to December 2014, collecting data over 200,000 square kilometres in the search area and producing high resolution maps of the sea floor to safely conduct the underwater search.
Survey vessels undertaking the bathymetric survey used a multibeam sonar mounted on the hull to obtain measurements and produce a map charting the water depth and hardness of the sea floor. High resolution multibeam data acquisition is time-consuming. It is a little like mowing grass, where bathymetry is mapped line by line.
In general, the world's deep oceans have had little exploration. Previous maps of the sea floor in the search area were derived from satellites and only indicated the depth of the ocean at a coarse resolution, not showing the shape of the sea floor in enough detail for safe navigation of underwater vehicles. These coarse maps provide data at a low resolution of approximately 1500 metres (per pixel), while the recent multibeam bathymetric survey collected data at 40 to 110 metres (per pixel). This newly acquired data is some of the first high resolution data available for these areas.
Sea floor in MH370 search area
Very little is known about the sea floor in the MH370 search area, as few marine surveys have taken place there. What was known, however, was that the search area encompasses the seabed on and around Broken Ridge, an extensive linear, mountainous sea floor structure that once formed the margin between two geological plates. These plates evolved and spread apart between 20 and 100 million years ago, under similar processes found today at spreading plate margins (such as the Mid-Atlantic Ridge).
The sea floor around Broken Ridge still retains many of the large geological structures typical of spreading plate margins where volcanism and tectonic movements produce volcanoes (now extinct), high rugged ridges and deep trenches.
The high resolution bathymetry data collected in the search for MH370 has revealed many finer-scale seabed features for the first time that were not visible in the previous low resolution, satellite-derived bathymetry data. It has also revealed regions of harder and softer sea floor composition (sediment versus rock). This information has been useful in identifying and discriminating certain features, but also in providing a guide on the complexity of the sea floor for the underwater search. The following 3D models present some of the features.
Visualisation of Sea Floor Terrain
Video: Bathymetry of the MH370 Search Area
Before the underwater search for MH370 could begin, it was necessary to accurately map the sea floor to ensure that the search is undertaken safely and effectively. Bathymetry survey vessels spent months at sea, scanning the sea floor with multibeam sonar to gather detailed, high-resolution data. The data has revealed many seabed features for the first time. This computer-animated `flythrough' shows a visualisation of some of the sea floor terrain in the search area.
Three-dimensional models of the sea floor terrain
These three-dimensional models of the sea floor terrain have been developed from high resolution (90 metre grid) bathymetric data from the survey in the southern part of the Indian Ocean.
These models show newly discovered sea floor features including:
- seamounts (remnant submarine volcanoes), up to 1400 metres high and often forming a semi-linear chain
- ridges (semi-parallel) up to 300 meters high, and
- depressions up to 1400 metres deep (compared to the surrounding seafloor depths) and often perpendicular to the smaller semi-parallel ridges.
The identification of these features will assist in navigation during the underwater search.
The data acquired as part of the bathymetric survey has been collected for the sole purpose of finding the missing plane and to bring closure to the families of those on-board. However, as it is some of the first high resolution data available in these areas, it is of great interest to the scientific community and will be released to the public by Geoscience Australia in due course.
For scientists, a greater understanding of deep ocean bathymetry is useful for a range of purposes, including geological interpretation to better understand plate tectonic history; as a baseline product in the creation of hydrodynamic models to gain knowledge on ocean currents and connectivity; the identification of sea floor features; and with the depth of oceans playing a major role in defining the habitat for flora and fauna - to locate areas where unique biological communities may exist.