The AP had a story on Monday about efforts to detect smuggling tunnels at the US-Mexico border, a technological challenge for which there is no simple solution today. There are a range of technologies that are used today- radar, sonar, electromagnetic waves, seismic technology – but subsurface detection is inherently difficult, and none of these is both accurate and precise enough to effectively uncover potential tunnels on a systematic basis. (Chapter IV of this National Academy of Sciences study from 2000 discusses the inherent limitations of these technologies).
The article notes:
A U.S. government effort to find tunnels used to smuggle drugs from Mexico into the United States with ground-penetrating radar and other high-tech gear has had little success.
Human intelligence has proven to be the most effective method to find secret passageways. Case in point: Last week’s discovery of the longest tunnel ever found along any U.S. border resulted from a tip….
“The problem is the technology picks up some kind of anomaly or variation of soil,” said Lauren Mack, a spokeswoman for U.S. Immigration and Customs Enforcement. “We go in with big backhoes and bulldozers, we spend all day doing it, and all we hit is rock or water tables.”
That’s what happened earlier this month when high-tech gear alerted authorities to a possible tunnel near Boulevard, a hamlet about 60 miles east of San Diego along the Mexican border. A full day of digging turned up nothing.
“It’s not there yet,” Mack said. “What we’ve seen so far just hasn’t proven itself to be effective.”
The article goes on to detail other efforts to find border tunnels on the southern border, and it makes clear that this recent incident is far from an anomaly. This 2003 piece from the San Diego Union-Tribune reinforces that idea, quoting from an unnamed government official who estimated the existence of at least 100 border tunnels.
The government definitely could benefit from new approaches to detecting border tunnels, a fact acknowledged in the Secure Border Initiative industry day last week when an official noted that the scope of the project included subsurface security. The key government agency researching this topic today seems to be the Army Corps of Engineers; this fact sheet details some of their initiatives. And the AP story provides additional context on research that might make a contribution to this effort:
Steve Danbom, a board member of the Society of Exploration Geophysicists who teaches at Rice University, said the tunnel offers a testing ground for promising technologies, including microgravity science and a technique known as multielectrode resistivity, which uses multiple electrodes to search for underground gaps in the soil.
Finally, maybe this kid is on to something that might address this issue….