Millions of shipwrecks are found scattered across the oceans. The recent studies reveal that satellites are used to locate the shipwrecks.
In a study published in the Journal of Archaeological Science, a marine geologist Matthias baeye at the Royal Belgian Institute of Natural science and colleagues reveal that wrecks produce Suspended particulate Matter (SPM) concentration signals. A high resolution ocean colour satellite data such as NASA’s Landsat-8 can detect these SPMS.
Baeye and colleagues wrote “Landsat-8 data is free and therefore the method presented in the study is an expensive alternative to acoustic and laser survey techniques”.
How does this work?
Distinctive linear plumes of these particles extend as far as 2.5 miles downstream from shallow shipwreck sites and are therefore easily detectable from space.
According to their study, the researchers analysed four known wreck sites near the port of Zeebrugge on the Belgian Coast. Located within 3 miles of each other on a sandy sea floor in less than 49 feet of water, the wrecks were all civilian vessels.
Findings:
Of the four, two ships, the SS Sansip and the Samvurn, sank after being mined during World War II. The Swedish steamship Nippon collided with another vessel in 1938, while the SS Neutron, a Dutch Steel cargo vessel, went down in 1965 after hitting a wreck, presumed to be the SS Sansip.
Using tidal models and a set of 21 cloud free Landsat- 8 images, the sediment plumes were mapped extending from the wreck locations.
- The substantial portions of the SS Sanship and the SS Samvrun were unburied, which was originating the SPM plumes. This could be traced downstream during ebb and flood tides.
- No SPM plumes were recorded in association with the SS Neutron and the SS Nippon, which are buried deeper in the seabed.
Baeye and colleagues wrote “SPM plumes are indicators that a shipwreck is exposed at the seabed and certainly not buried”.
According to the researchers, it’s the exposed structure of the ships that creates scour pits around the wrecks. These act as sinks where fine-grained suspended material is deposited during slacks (the period of relatively still currents between ebb and flood tides.)
- The scour pits then act as sources for suspended material when the bottom current increases again.
- The moment sediments reach the surface, they create linear plumes. It is not assured whether depth is a limit to the new wreck-detecting technology since the four wrecks in the study all rest in relatively shallow waters.
- Satellites may not image plumes from deep sea wrecks. Still, given the millions of ship wrecks spread all over the Oceans, having one more tool to catch them is significant.
The researchers concluded that “The capability to detect the presence of submerged shipwrecks from space is of great value to archaeological scientists and resource managers are interested in locating wrecks”.
Source: Discovery News
