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Defying assertions that earthquakes cannot be predicted, an Italian court convicted seven scientists and experts of manslaughter Monday for failing to adequately warn residents before a temblor struck central Italy in 2009 and killed more than 300 people.

The court in L'Aquila Monday evening handed down six-year-prison sentences to the defendants, members of a national "Great Risks Commission." In Italy, convictions aren't definitive until after an appeals trial, so it is unlikely any of the defendants would face jail immediately.

The trial -- described in 2011 by a USGS scientist as "a witch hunt" -- sent shock waves of its own through the international science community.

"It's a sad day for science," said seismologist Susan Hough, of the U.S. Geological Survey in Pasadena, Calif. `'It's unsettling."

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Tom Jordan, a seismologist with the University of Southern California (USC), chaired an international committee on earthquake forecasting convened in Italy following the 2009 quake. He agreed that scientists worldwide were rattled.

“It’s widely viewed within the scientific community that this is an unfair result,” Jordan told FoxNews.com. "We can’t predict earthquakes. We can only forecast them with low probability."

Among those convicted were some of Italy's most prominent and internationally respected seismologists and geological experts, including Enzo Boschi, former head of the national Institute of Geophysics and Volcanology.

"I am dejected, desperate," Boschi said after the verdict. "I thought I would have been acquitted. I still don't understand what I was convicted of."

"I consider myself innocent before God and men," said another convicted defendant, Bernardo De Bernardinis, a former official of the national Civil Protection agency.

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The trial began in September 2011 in this Apennine town, whose devastated historic center is still largely a ghost town.

The defendants were accused in the indictment of giving "inexact, incomplete and contradictory information" about whether small tremors felt by L'Aquila residents in the weeks and months before the April 6, 2009, quake should have constituted grounds for a quake warning.

The 6.3-magnitude quake killed 308 people in and around the medieval town and forced survivors to live in tent camps for months.

Many much smaller earth tremors had rattled the area in the months before the quake, causing frightened people to wonder if they should evacuate.

Prosecutors had sought convictions and four-year sentences during the trial. They argued in court that the L'Aquila disaster was tantamount to `'monumental negligence," and cited the devastation wrought in the southern United States in 2005 when levees failed to protect the city of New Orleans during Hurricane Katrina.

A defense lawyer, Filippo Dinacci, told reporters that the sentence would have "big repercussions" on public administration since officials would be afraid to "do anything."

Relatives of some who perished in the 2009 quake said justice has been done. Ilaria Carosi, sister of one of the victims, told Italian state TV that public officials must be held responsible "for taking their job lightly."

The world's largest multi-disciplinary science society, the American Association for the Advancement of Science, condemned the charges, verdict and sentencing as a complete misunderstanding about the science behind earthquake probabilities.

Earthquakes are, of course, nearly impossible to predict, seismologists say. In fact, according to the website for the USGS, no major quake has ever been predicted successfully.

"Neither the USGS nor Caltech nor any other scientists have ever predicted a major earthquake," reads a statement posted on the USGS website. "They do not know how, and they do not expect to know how any time in the foreseeable future."

Jordan told FoxNews.com his report called for the creation of a a system that puts out information about earthquake risk on a regular basis, something he called "operational earthquake forecasting." Even the U.S. system is not ideal, he noted.

"The scientists get caught between a rock and a hard spot in terms of trying to answer the question, 'will there be a big earthquake,'” he told FoxNews.com. The ruling could have a "chilling effect" on future communication efforts, he added.

The verdict also calls for damage payments that could add up to hundreds of thousands of euros, Science magazine wrote.

The Associated Press contributed to this report.