Making the Invisible Visible
The dynamics of surveying the seabed of Malta with the help of an automated underwater vehicle (AUV)
The inescapable presence of the sea has shaped the islands history, traditions and culture bringing with it not only goods, but also people and their ideas. For millennia now, the people of Malta and Gozo have witnessed maritime traffic, be it for commerce, travel or war.
The surroundings
The seabed of the Maltese Islands is a reflection of this traffic, through the foundering of ships off the island’s coasts, the jettisoning of cargo or the resting place for ships and aircraft from recent conflicts
Context for the research
Malta’s 7500 years of history have shaped the island’s landscape and it's culture. Our aim is to understand to what extent Malta’s rich history is also reflected on the seabed surrounding the island.
AUV on the surface (2019) by University of MaltaUniversity of Malta, Department of Classics & Archaeology
The only way to determine what lies on the seabed is to survey it. A side-scan sonar, mounted on an Automated Underwater Vehicle (AUV), is the main tool utilised to achieve this goal.
Survey plan (2020) by University of MaltaUniversity of Malta, Department of Classics & Archaeology
The seabed is scanned and mapped by systematically dividing the areas of interest into survey blocks
Survey block (2020) by University of MaltaUniversity of Malta, Department of Classics & Archaeology
Approximately five square kilometres are covered at a resolution that allows the team to annotate human-made objects on the seabed.
AUV Work day (2020) by University of MaltaUniversity of Malta, Department of Classics & Archaeology
The generated files are ‘stitched’ together to create a mosaic of the surveyed area. Using satellites and an inertia navigation system, all data generated by the AUV are geo-referenced, and inserted into a map, which allows us to create a general image of the surveyed seabed.
Possible "anomaly"
Once data are collected and mosaiced the analysis is started on a line by line basis. During this part of the project we eventually start to encounter what are called ‘anomalies’ or ‘targets’.
Posible archaeological target (2020) by University of MaltaUniversity of Malta, Department of Classics & Archaeology
These could be anything from potential anthropic elements, such as aircraft, shipwrecks, or even a modern transport container, to natural features on the seabed.
Target of archaeological interest (2020) by University of MaltaUniversity of Malta, Department of Classics & Archaeology
All targets of archaeological interest are marked, saved and prioritised.
Higher definition documentation
Once a target is marked, a second dive is planned with the AUV in order to generate higher resolution data. This is achieved by flying the AUV closer to the seabed using a higher frequency sonar (1600KHz).
Additional footage
During the high resolution dive, a video camera is mounted onto the AUV to provide additional verification footage of any potential targets. This footage provides an additional perspective to what lies on the seabed, and allows the team to gain a more insightful view into the data.
Wrecking site (2019) by University of MaltaUniversity of Malta, Department of Classics & Archaeology
Documentary research begins on targets securely identified as material culture. In cases of aircraft or modern wrecks, these are usually easily identifiable from the sonar data.
Finding references
For relatively modern wreck remains from the First and Second World War, sources such as engineering blueprints can provide essential information that aids in the identification of the specific variant type of aircraft, vessel or other remains.
Photography: University of Malta & Heritage Malta.
Special thanks to everyone who participated in this project and made it possible.
