AN EARLY warning system for destructive underwater waves has passed its first test in the Andaman Sea, north-west of Sumatra, Indonesia.
The system is designed to look for solitons, powerful pulses that can be triggered at the boundary between layers of dense and less-dense water, often when a step change in the sea鈥檚 depth disrupts a tidal flow. On the surface they can appear as relatively innocuous white horses, but deep down they can generate powerful vertical currents that are a hazard to divers, says Martin Goff, a UK-based expert on solitons at Fugro GEOS, a geosciences consultancy.
Solitons can be a big problem for oil rigs. In one incident in the Andaman Sea, a soliton shunted a drilling rig so hard it broke the drill string, the rotating pipe that drives the drill bit. Repairing such damage can be seriously expensive.
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To protect the rig, Goff and his colleagues built two buoys able to detect the rapid changes solitons create in water temperature, salinity and current flows. Having located the source of the solitons from satellite images, they placed the two buoys at intervals between the source and the rigs, and used the data sent back to determine the size and speed of the approaching waves.
Fugro operated the system for three months in 2008, during which time it issued several warnings of solitons to the rig owners. This gave staff 10 hours to cease drilling and prepare. With crews able to tighten the moorings in advance, the solitons passed through without incident.
鈥淎dvance warnings issued to rig owners gave staff 10 hours to cease drilling and prepare鈥�
鈥淭his is significant,鈥� says Chris Jackson at Global Ocean Associates, a remote-sensing consultancy firm based in Alexandria, Virginia. 鈥淚t鈥檚 the first deployed system with a real-time warning capability.鈥�
Read more: Oceanology: Farther, deeper, faster
