Geoscience Australia is providing extensive advice, expertise and support to the Australian Transport Safety Bureau (ATSB).
The ATSB is leading a seabed mapping and underwater search for missing Malaysia Airlines flight 370 in the southern Indian Ocean.
Bathymetry is the study and mapping of the sea floor.
It involves obtaining measurements of the depth of the ocean and is equivalent to mapping on land. 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.
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.
This expertise proved critical in understanding the environment in which the search is operating.
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.
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.
The image on the left shows data at around 3400-metre resolution (data acquired predominantly by satellite altimetry), while the image on the right shows data with a combination of 250-metre and 50-metre resolutions (data acquired by bathymetric surveys from a vessel).
The higher resolution data on the right shows underwater features much more clearly.
This figure is for illustrative purposes only and does not show data from the search area.
The bathymetric survey was conducted from May to October 2014, collecting data over 150,000 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.
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 50 to 150 metres (per pixel).
This newly acquired data is some of the first high resolution data available for these areas.
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 50 to 150 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).
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.
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
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' (above) shows a visualisation of some of the sea floor terrain in the search area.
Three-dimensional models of the sea floor terrain
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' (above) shows a visualisation of some of the sea floor terrain in the search area.
3D models of sea floor terrain gallery
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:
Scientific understanding
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.
Scientific understanding
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.
Links :
- GeoGarage blog : Search for MH370 : hopes fresh drift model will improve debris search in Australia / New map exposes previously unseen details of seafloor / Flight MH370: New search images reveal seabed details / Malaysia Airlines flight MH370: Satellite data to be re-examined as ‘more difficult’ phase begins, search on ocean floor widened / MH370: How do underwater sonar subs work? / Appeal to search missing Malaysian flight / Why locating MH370 in the Southern Ocean is so difficult / Malaysia Airlines Flight MH370: Search reveals extent of ocean garbage / Malaysia missing plane search China ship 'picks up signal'
- ATSB : MH370
- EGU : Using seafloor mapping to find missing Malaysia Airlines flight MH 370 (Guest Post: Dr. John W. Jamieson)
YouTube : Mapping the deep ocean: Geoscience Australia and the search for MH370
ReplyDeleteA short film describing the processes of bathymetric mapping and side scan sonar, used to gather data within the search area for missing Malaysia Airlines flight MH370.