An Israeli technology that's groundbreaking - literally

05/04/2011 20:25


Archeologists around the world rely on a repertoire of only partially effective methods - historical texts, surface indicators and technology - to decide where to break ground to uncover sites of archeological significance. But the decision often comes down to educated guesswork, because it isn't possible to get a really clear look at what is going on underground.

Now it is, thanks to Prof. Lev Eppelbaum of Tel Aviv University's Department of Geophysics and Planetary Sciences. Eppelbaum has created a new non-disruptive, ecologically sound geophysical methodology, an "algorithmic toolkit," capable of cutting through the "background noise" of irrelevant underground features. It can detect archeological structures and artifacts up to 150 meters deep, producing an accurate 3D or even 4D image.

"It's the most conclusive evidence ever produced about what's below the ground's surface," says Eppelbaum, who immigrated to Israel from Azerbaijan in 1990. "Until now it was very difficult to reveal relevant archeological components, given the strong background noise of irrelevant components, and now it's possible."

Commonly used methods including radar, satellite imagery and infrared technology often produce inconclusive results, and can only be applied to sites located some distance away from modern urban and industrial areas, due to interference, or "noise" produced by modern underground features like water pipes, telephone cables and electrical power lines.

Taking a picture of the underground landscape

Eppelbaum's method, dubbed the "Multi-PAM" (physical archeological models) System, uses a combination of up to seven different geophysical components to get an estimation of the underground landscape: magnetism; gravity; self-potential; VLF (very low frequency electromagnetic radio transmissions, the type the military uses to communicate with nuclear submarines deep below the water's surface); resistivity; induced polarization (based on differences in electromagnetic properties); and piezoelectricity, which detects minerals and some archaeological objects made from fired clay.

In most cases, not all seven methods are applied; mostly because of the expense. "Usually we can get an accurate image using two or three methods per site," the former chess champion says. Eppelbaum explains that the survey technology can be strapped to a remote-operated unmanned aircraft, the kind most often used by the military, and sent to scan the desired tract of land. The data it returns is then converted into an advanced mathematical algorithm that can be translated into a model image.

The new methodology is somewhat costly to perform - in the thousands of dollars range. And, as Eppelbaum puts it, "Archeology is not a profit maker." However, the system has the potential to save archeologists a lot of money and time in the long run, since surveyors will be able to determine the location of sites with much more accuracy.

Archeologists typically don't have the resources to explore more than five percent of a site over a period of many years. "Without geophysics, millions of dollars will be spent looking for archeological sites incorrectly and perhaps hundreds of archeological sites will be ruined because of industrial development," projects Eppelbaum.

Hurdles to overcome

Besides the expense of the new technique, there may be a more insidious factor preventing its popular adoption by excavation administrators. "Even if the money did exist for it, many archeologists would be hesitant to take it on because of the implied reduction in time and budget that would result," he says. There also may be objections from property developers and government officials in Israel, who already need to consult with archeologists before starting to build in particular areas.

The method has nevertheless been tested quite extensively, both in Israel and in Italy, Austria and the United States. In Israel, which boasts the greatest density of archeological sites in the world - an estimated 30,000 current sites with another 20,000 waiting to be found in a country of some 22,000 square kilometers - the method has been tested at 20 sites including Banias and Sha'ar HaGolan in the Golan Heights; Halutza, south-west of Beersheva; Nahal-Zehora, northeast of Tel Aviv; Munhata, south of Lake Kinneret (Sea of Galilee); Yodefat, northeast of Haifa; and Tel Kara Hadid, north of Eilat.

In Israel, Multi-PAM may be useful not only to survey the enormous number of archeological sites underground, but also to detect minerals and elements under the earth and sea's surface, and to uncover terrorist tunnels. "We are happy to apply it to other sites if we have the possibility," says Eppelbaum.

Until the advent of Multi-PAM, archeologists were largely unaware of geophysical methods. According to Eppelbaum, some 95% of archeologists don't understand such methods and prefer to jump right into excavation. Nowhere is this truer than in Israel, where unlike Europe and America, there are no dedicated geological-archeological interdisciplinary centers. Over the last three years, Eppelbaum has pushed for the creation of such a center at TAU.

"For Israel, I think archeo-geophysical investigation is an absolute necessity," he says. "But it's hard to gather the support."


Share |