Best Of Both Worlds
A technique developed at Belgium’s LGIH lab in the University of Liège during the late 1980s to assess the dredge-ability of rocks has helped paint an underwater picture of Monaco Bay, writes G-Tec’s general manager Jan Robert Huisman
The best known seismic measuring technique in marine engineering is the sub-bottom profiler (SBP), which provides clear pictures of rock levels, but gives no information about characteristics as the seismic wave bounces back from the top of rock without penetrating it.
But LGIH’s refraction technique – which is not so well known – uses seismic signals propagating in the rock that allow us to measure the propagation velocity of the seismic compressive waves, commonly called ‘seismic velocity’. It’s been further developed and used by G-Tec for marine applications since 1993, resulting in today’s Nemo refraction device that can be used in water depths up to 80m.
Background
So when the Monegasque authorities – Direction de la Prospective, de l’Urbanisme et de la Mobilité – decided to better know and understand their surrounding marine environment and award a geophysical survey contract to G-tec, Nemo was an obvious tool.
The principality’s magnificent scenery owes much to the complexity of the loc ...