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Don't blame sharks for Asian Internet problems, experts say

Tim Hornyak | Jan. 22, 2015
It may not be Shark Week, but don't tell that to people in Vietnam.

The continuing importance of marine cables has been highlighted by Google's recent investments in the infrastructure. NEC, one of the top three submarine cable makers along with Alcatel-Lucent and TE SubCom, is part of a consortium including Google working on the US$300 million FASTER cable system between Japan and the U.S. With six fiber pairs and 100 wavelengths, it will have a capacity of 60Tbps when it comes online in 2016. As Google described it, that's about ten million times faster than your cable modem.

NEC manufactured cables used in the 20,000km-long AAG system. Masuda says that the AAG Consortium is responsible for maintaining the link but said that cables can get cut by dropped anchors, trawler nets and undersea earthquakes. NEC's underwater cables, he said, are rated to last for 25 years at depths of up to 8 kilometers.

Biologists, meanwhile, say sharks are known to bite submarine cables. How much damage they can cause depends on the species and the cable itself.

"Underwater cables are sometimes bitten and damaged by sharks," Kazuhiro Nakaya, a marine scientist and professor emeritus at Hokkaido University, said via email. "Although 8,000m below the sea level is a little too deep for sharks (the deepest shark record is less than 5,000m), it is possible that the cables settled shallower areas are damaged by sharks."

Sharks are attracted by electromagnetic fields they can pick up through sensing organs called electroreceptors, which are located in their snouts and heads.

"They cruise along the bottom trying to detect bioelectric fields from prey living on the bottom and also looking for the light flashes of bioluminescent prey," Dean Grubbs, an associate scholar scientist at Florida State University Coastal and Marine Laboratory, said via email. He was referring to the bluntnose sixgill, which he said is the shark in the 2010 video on YouTube.

"Though their jaws are relatively weak, they have saw blade-shaped teeth and tend to bite large food items (including carrion like dead whales) and then twist their large body until they saw out a hunk of flesh. It is possible that a large shark feeding in this way could damage submarine cables."

Grubbs said he has seen experiments showing sharks orienting to a weak electromagnetic field emanating from an electrode. A transatlantic cable laid in the 1980s by AT&T was found to have been damaged several times by undersea attackers, primarily crocodile sharks, Grubbs said. He added, however, that "most deep-sea sharks have relatively weakly calcified jaws so their bite force is quite low."

That, combined with better protection for cables than in the past, suggests human activity is what has been affecting the Internet in Vietnam. According to the management consortium's Costin, anchoring and fishing were responsible for all the faults last year. It's expected to be fully restored by Jan. 27.

 

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