News Service from House Harris

AFR: Tunnel-sniffing revolution on Gaza's last frontline

CAIRO, Jan 13 AFP - From radar to fibre optics and sonar to sweat, the quest to find an efficient method of unearthing Gaza's smuggling tunnels has become crucial to achieving a truce in the beleaguered territory.

The United States has promised Egypt $US33 million ($A48.63 million) of equipment to detect the tunnels which Israel says are used to smuggle weapons, including the rockets that are regularly fired at Israel, as well as food and medicine.

And while Israel says it will not halt its offensive until it has guarantees that tunnel smuggling will end, neither the US nor Egypt will answer questions about what techniques are being used along the 14km border.

The Nazis buried microphones to detect POW escape attempts, while Ground Penetrating Radar (GPR) invented by the US to combat Viet Cong tunnels has been further developed by archaeologists in their quest for the secrets of the past.

Such methods, as well as more bizarre techniques such as sniffing around for human sweat, have remained favourites of tunnel busters from Mexico to Northern Ireland.

Lawrence Conyers of the University of Denver says that GPR -- in this case dragging a radar behind a moving vehicle -- is the best tunnel detecting technology, especially for the sandy type of soil on the Egypt-Gaza border.

"But it's not like turning on a metal detector and having it 'beep' when it finds things," he told AFP. "Data processing and interpretation are needed."

He says that it can be difficult to tell the difference between the top and the bottom of a tunnel using radar techniques.

"Sometimes the radar energy gets into the void space and bounces around a good deal before coming back to the surface, which makes it very complicated."

Egyptian soldiers have reportedly been trained to use the US equipment, but, says Conyers, "it takes someone who has a real interest in doing it, they must make it more than just a 'soldier's job'".

The soldier must learn how to collect the data while dragging the device behind a truck travelling at 30km/h and "take it on a laptop and process it and then spend time looking hard at it".

Conyers dismisses other tunnel busting methods such as sonar, magnetics, resistivity, electromagnetic induction as inferior to GPR.

Another technique, detecting tiny muon particles created by cosmic rays, is "wacky stuff and only just beginning to be understood", he says.

But Israeli researchers have now developed a potentially revolutionary system which uses a fibre optic cable that can detect and identify the most minute soil movements -- and requires no expertise to operate.

"The advantage is that we can monitor 30 kilometres of fibre using only one computer and you don't need to go along the border because it's already buried underground," says Dr Assaf Klar of Israel's Technion Institute of Technology.

"And it costs less than a few dollars per metre," says Klar, who came up with the idea while doing research on the effects of building work on tunnels and pipelines in Britain.

"The major part of the research was the computer brain that can recognise that it's a tunnel and not just traffic or a vehicle or rain, to distinguish the signal of the tunnel compared to other signals," Klar told AFP.

"It's just a program at the end and it will tell the soldier 'I recognise a tunnel at this and this metre. Please go and check'. It's very easy," says Klar, adding that a working prototype could be ready in two months.

But what if a smuggler simply cuts the fibre optic cable?

"You can put two fences either side of the cable to protect it, but even if there's no fence, the cable is buried one metre down and you must start to excavate to reach it."

"And once you do that the cable feels soil movement and it will alert that someone is excavating. Even if someone does manage to cut the cable then we know immediately exactly where it is and just splice it together again."

But Klar admits that while his system is excellent for detecting the digging of new tunnels, it's of little use against the hundreds that reportedly already exist on the border -- for them, old school GPR remains the best way to sniff.