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.