Bermuda Triangle mystery solved?
Massive gas bubbles rising from the sea floor may be capable of sinking ships and could explain the disappearance of a vessel in a North Sea "Bermuda Triangle", Melbourne researchers have concluded.
In a report published in the September issue of the American Journal of Physics, Monash University's Professor Joseph Monaghan and honours student David May said that a trawler discovered resting in a large methane crater off the east coast of Scotland may have been sunk by a huge gas bubble. The possibly lethal gas bubbles are created by underwater deposits of methane that have built up over thousands of years.
"It's long been known that there are pockets of methane gas, known as methane gas hydrates, beneat the ocean floor that could erupt if they're disturbed or if their internal pressure becomes too large," Professor Monaghan said.
The massive gas bubbles had the potential to cause aircraft to crash, Mr May said yesterday. "In the Bermuda Triangle, methane gas is known to be present and the release of that gas could cause not only boats to sink, as shown in our study, but also aeroplanes to crash," he said. The gas could cause an explosion if it came in contact with the hot engine of a plane.
Oil-drilling platforms are aware of the dangers of ocean floor gas bubbles and have safety procedures to follow if they hit a methane pocket. But the discovery of the fishing trawler in the North Sea suggests that not all vessels were as well prepared. Sonar surveys of the ocean floor 150 kilometres east of Scotland have revealed high levels of methane and gas eruption sites. At a site known as the Witch's Hole, a documentary film crew in 2000 discovered a wreck resting in the centre of an underwater crater, likely caused by a huge methane gas release. The wreck was a 22-metre, steel-hulled fishing trawler, built between 1890 and 1930. The trawler was relatively undamaged and was horizontal on the sea bed.
From laboratory experiments, the Monash University researchers were able to conclude that large gas bubbles, theoretically, had the ability to sink ships. "It is quite possible that the trawler languishing in Witch's Hole was sunk by a bubble with a radius equal to or bigger than the trawler's hull," Professor Monaghan said.
Mr May said they had made a small perspex boat and conducted a number of experiments examining how the size of the bubble related to the size and position of the boat.
They found that if a ship was directly above a gas bubble it was relatively safe, but a vessel on the edge or in the trough of a bubble may be swamped.
"The sinking occurs because a mound of water is raised above the region where the bubble reaches the surface," Professor Monaghan said.
"The flow from the mound creates a deep trough on each side of the mound, and the flow from the mound carries the boat into the trough."
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