Geohazard Investigation within the Irish Sea utilizing Seismic and Seabed Mapping Methods (GIST)
twenty fourth October – sixth November 2019
Hello all, my title is Jan Majcher and I’m a 2nd 12 months PhD researcher from Ulster College, reporting from the RV Celtic Voyager.
My job on board is to supply seabed mapping information for my analysis into scour processes at shipwreck websites. I’m nonetheless admiring the vessel’s hydrographic gear, together with cutting-edge dual-head multibeam echosounder, which might be mechanically lowered under the keel to keep away from noises brought about for instance by bubbles forming close by the hull. I’m effectively acquainted with the outputs which this gear can ship (Fig. 1). I plan to do repeat survey of chosen websites, persevering with the custom of accumulating the absolute best high quality of hydrographic information over shipwrecks; no strain so! Thankfully, we’ve got the most effective crew on board with further assist on land (thanks Fabio Sacchetti, Ruth Plets and Rory Quinn) to carry out the duty! I have to admit that the ocean state is in our favor too.
This 12 months we are going to resurvey World Battle I websites; RMS Leinster, SS Polwell, SS Hare, SS WM Barkley, SS St Michan and HMS Vanguard. However what’s all of it about? Why will we acquire extra information on the shipwreck websites which had already been surveyed so exactly earlier than? The marine near-seabed setting tends to be very dynamic, particularly in coastal areas. The sediments are shifting continuously, with dunes greater than the shipwrecks themselves progressing over them. A number of the wrecks trigger the sediment to be washed away or scoured – typically to nice distances (Fig. 2), creating scour holes – these in flip can affect the shipwrecks considerably. A few of them are actually being buried inside their very own erosional scour pits under the encircling seabed. What does it imply for the state of preservation of the shipwrecks, a few of that are so in style amongst divers and essential from the cultural heritage viewpoint? Are the scour pits nonetheless deepening or have they stabilized already? Are the megadunes progressing on the tempo, which might be harmful for the shipwrecks? We are able to discover solutions to all these questions by evaluating high-quality datasets which have been acquired through the years. They are going to enable us to see native modifications in bathymetry on the websites, with a centimetric accuracy.
Fig. 2: SS Polwell web site with depositional and erosional scour options extending as much as 1 km from the shipwreck.
The data concerning the native dynamics on websites additionally offers us with a useful info for offshore engineering. For instance; when a wind farm basis is positioned on a seabed, it is going to trigger the scour of native sediments and be affected by this course of in the same means because the shipwrecks we survey. We are able to say that they’re indicators, or in different phrases pure laboratories which permit us to garner details about the impact native sediment dynamics has on man-made buildings.
Fig. 3. Multibeam’s workstation with a ‘multibeamer’ on obligation. Thankfully, our work is a workforce effort, so we’ve got sufficient eyes to look into all of the screens.
Want us good luck and keep tuned for the following updates from our cruise!
Blogs from the earlier surveys performed over the shipwrecks might be discovered at:
Submit by Jan Majcher, PhD researcher from Ulster College.