Tunnel detection tech can work for Israel, says expert

Israel has sent troops into Gaza City to blow up terrorist tunnels, at heavy cost. What puzzles one expert is why the IDF hasn’t instead used technology to find the tunnels, just as it has exploited high-tech capabilities for the conflict’s greatest success — Iron Dome.

Paul Bauman, a Canadian who is one of the world’s foremost experts on discovering underground tunnels and voids, insists that the technology exists and has been used in the US, Canada, Korea, and other places. “We actually did some work with the IDF some years ago, showing them how the technology we’ve developed works,” Bauman told The Times of Israel in an interview. “They were interested, but there was no follow-up. Why, I couldn’t say.”

The IDF said it could not comment on the matter.

Had the army worked with Bauman, using the sophisticated methods he has developed and successfully employed over the past decade, things might have been different. While there is no foolproof, single tech solution to discovering tunnels, a combination of several techniques — radar, tomography, and seismic measuring — could give Israel a technological advantage over Hamas, creating a map of what is happening under the surface, and making it much easier to find tunnels and the terrorists who dig them.

Bauman knows all about underground exploration. Along with University of Hartford archaeologist Richard Freund, he gained fame as the team that discovered the lost city of Atlantis — or at least what could be Atlantis, located beneath an underwater marsh outside the Straits of Gibraltar off the coast of Spain.

Using electrical resistivity tomography (ERT), a sort of MRI for below the surface exploration, Bauman and Freund found artifacts, including bronze-age statues, that were carbon-dated to about 4,000 years ago, corresponding to the account of the life and death of Atlantis, as told by Greek philosopher Plato. According to Freund, it is likely that a tsunami destroyed the city, burying it underwater. The saga was memorialized in a 2011 documentary called Finding Atlantis that aired on the National Geographic Channel.

Paul Bauman (Photo credit: Courtesy)

Bauman, technical director of the geophysics group at the Calgary, Canada offices of Australian resources consulting firm WorleyParsons, has also worked with Freund on numerous underground exploration projects in Israel, including discovering a Qumran cave, using ERT to map the floor of the Cave of Letters (where some of the most important Qumran Dead Sea Scrolls were found), enabling archaeologists to discover new artifacts and develop a map of the Second Temple-era Jewish revolt.

It was on one of his exploration trips to Israel that Bauman showed the IDF some of the techniques it could use to discover underground tunnels. At the time, after another Gaza flare-up, Operation Cast Lead in 2009, a Technion team led by researchers Dr. Raphael Linker and Dr. Assaf Klar were developing a system that uses a fiber optic cable buried one or two meters beneath the surface to detect underground movement. The system builds what is essentially an underground fence using BOTDR (Brillouin optical time-domain reflectometry) technology, which measures the stress on the cable underground.

The amount of stress may be very small, the team said, and its research shows that even small levels of deformation can be detected, making the system perfect for keeping tabs on tunnel builders. The cable is cheap, and as much as 30 kilometers of the border can be monitored simultaneously using one device. It’s not clear if the IDF considered that system as well, and in an email this week, Linker said that the system is still under development.

One thing that Israel has considered in the past to deter the Gaza terrorists’ propensity for tunnel construction is a moat. The moat plan, first proposed in 2004, before Israel withdrew from Gaza, would have hadIsrael dig out an inlet along the Gaza-Sinai border, allowing seawater to flow in, thus preventing tunnel digging — or making it much more difficult. At the time, Israel’s main concern was preventing Gazans from smuggling rocket manufacturing material in from Sinai. The problem of underground terror tunnels into Israel wasn’t yet on the IDF’s radar.

A moat, said Bauman, would be a “dumb” idea, because it would pollute the coastal aquifer that both Israel and Gaza rely on for water. Much better, he said, would be a technique like underground radar to find tunnels. “Israel has been very interested in this, and Israeli companies are working on underground radar systems,” said Bauman. “In an underground radar system, you aim the wave down below the ground, and when you get back a signal that is an anomaly — indicating that there is something different about the area you just checked than other areas — you know you’ve found something worth investigating.”

There are limitations to the system, though. “Depending on the frequency of the radar wave, you can have a system that can ‘see’ as far down as 100 meters, but at low resolution, or just 10 meters at a better resolution,” Bauman said. Radar could be very useful in discovering larger concrete tunnels, which have metal rebar in them — concrete and metal being much denser than the gypsum and salt-rich soil around the Gaza border — but not for the simpler, smaller wood-reinforced tunnels.

Radar is just one technique Bauman uses in his exploration of underground tunnels, lakes, and voids — the kind of work he does every day in western Canada, where he searches for old mines and dugouts, in order to ensure that new buildings aren’t constructed in the wrong place. Besides radar, Bauman uses ERT — a technique that lets researchers do inverse modeling of underground features.

“You place electrodes in or on the ground, and send down current. You then measure the voltage that is returned, measuring the resistance of the earth. Again, an anomaly indicates that further investigation is necessary,” said Bauman. For Israel, ERT would likely be a very successful technique. “Israel already has a fence around Gaza, so the electrodes could just be added to the existing foundation of the fence. You could set up an automated system that would send down current probes every few seconds, building a baseline picture of what the readings should be — and setting off an alarm as soon as an anomaly, indicating a tunnel or underground movement, is detected.”

Yet a third technique Bauman has used successfully in the past is a seismic detection technique called MASW — multichannel analysis of surface waves, measuring shear-wave velocity. “You use an acoustic source, like a hammer, to knock the ground and create sound waves known as ground roll. When there is anomaly in the resulting waves when you pass over an area indicating that the area below where you knocked is different than other areas, that is also an anomaly that needs to be investigated.”

Israel is far from alone in dealing with tunnels. The techniques described by Bauman have been used with varying degrees of success to discover tunnels dug by smugglers and drug dealers under the US-Mexican border, and on the border between North and South Korea. “You have to remember that tunnels, for smuggling or terror, are not at all a uniquely Israeli problem,” said Bauman. “Other countries have similar problems, and are searching for tech solutions to tunnel detection.”

The secret of successful tunnel detection, said Bauman, is not to rely on a single technology — but a combination. “Each of these methods has their advantages and disadvantages, but the objective should be building a map of the underground features around Gaza, so that, with constant monitoring, changes can be detected, which would indicate tunnel construction or use,” said Bauman. “Each of these techniques can contribute to building that map. Unfortunately, there’s no single silver bullet, but keeping a watchful eye what is happening underground will, I believe, go a long way to solving the problem.”