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Can radon gas leaks predict earthquakes?

An Italian researcher says he predicted Monday's quake. Is his claim credible?

By Peter N. SpottsStaff writer of The Christian Science Monitor, Anna MomiglianoCorrespondent of The Christian Science Monitor / April 8, 2009

Boston and Milan, Italy

The earthquake that devastated L 'Aquila, Italy, on Monday casts a spotlight on the challenges scientists face as they try to improve earthquake forecasts.

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Specifically, it raises the question of whether the release of radon gases from the ground can accurately predict the arrival of a temblor.

The short answer? Maybe.

Giampaolo Giuliani, a researcher at Italy's Gran Sasso laboratory, alerted authorities in the region of Abruzzo that a quake was imminent – and was condemned for raising a false alarm. Mr. Giuliani declined requests to be interviewed, and according to his wife, who was also reached by phone Tuesday, is busy working at his lab.

While the details about the timing and location of Giuliani's warning remain fuzzy, he reportedly based his warning on radon emissions that instruments at his lab were picking up.

Abruzzo is not an easy place to test such an approach, according to US scientists. It's a mountainous, quake-prone patch of central Italy that covers nearly 4,200 square miles.

It's about as complex a place geologically as one can imagine, notes Felix Waldhauser, a researcher at the Lamont-Doherty Earth Observatory in Palisades, N.Y.

It's under pressure from one of the world's large crustal plates, the African plate, which is rotating. It's also influenced by smaller "microplates" in the region. As a result, Abruzzo hosts several broad fault types. But while they fall into a few broad classifications, each fault carries its own unique traits.

Over the years, scientists have explored a number of techniques for trying to determine with some precision when and where a quake will strike. Radon, a naturally occurring radioactive gas, has been listed as one of several possible indicators of an impending temblor.

Indeed, Giuliani said during a March 23 video interview (click here to view it in Italian) posted on a local Abruzzo website, "Our instrument ... allows us to see continuously the seismic precursors within this element [radon], which manifests itself between six and 24 hours ahead of a quake."

Yet even he reportedly had the quake mistimed by at least a week.

That's one reason why the American scientist who first proposed studying radon emissions – and other potential signals – remains modest about their applications.

For all the study that potential precursor signals (such as radon and the electrical properties of fluids moving through faults) still receive, no single indicator or combination of indicators has panned out as a reliable quake predictor, according to Christopher Scholz, a geophysicist at the Lamont-Doherty observatory. He and two colleagues first set out the proposition that such phenomena might serve as quake warning signals 36 years ago, based on lab experiments of how rocks and liquids behave as stress builds along a fault.