Six Italian scientists and a government official were sentenced to six years in jail on Monday for multiple manslaughter in a watershed ruling that found them guilty of underestimating the risks of a killer earthquake in 2009.

They were also ordered to paymore than nine million euros (almost $12 million) in damages to survivors in the devastated medieval town of L'Aquila in a case that has sparked outrage in the international science community.

Seismologists in Italy and beyond were horrified by the unprecedented sentence and argued that all science was being put on trial.

Under the Italian justice system, the seven remain free until they have exhausted two chances to appeal the verdict.

Prosecutor Fabio Picuti had asked for jail sentences of four years for each defendant for failing to alert the population of the walled medieval town to the risks, days before the 6.3-magnitude quake that killed 309 people.

"I am crestfallen, desperate. I thought I would be acquitted. I still don't understand what I'm accused of," said Enzo Boschi, who was the head of Italy's national geophysics institute (INGV) at the time.

All seven defendants were members of the Major Risks Committee which met in L'Aquila on March 31, 2009 -- six days before the quake devastated the region, tearing down houses and churches and leaving thousands of people homeless.

Picuti had slammed the experts for providing "an incomplete, inept, unsuitable and criminally mistaken" analysis, which reassured locals and led many to stay indoors when the first tremors hit.

"This is a historic sentence, above all for the victims," said lawyer Wania della Vigna, who represents 11 plaintiffs, including the family of an Israeli student who died when a student residence collapsed on top of him.

"It also marks a step forward for the justice system and I hope it will lead to change, not only in Italy but across the world," she said.

The bright blue classroom-sized temporary tribunal in L'Aquila -- built on an industrial estate after the town's historic court was flattened in the quake -- was packed with lawyers, advisors and international media for the verdict.

Four of the defendants were in court, as well as a small group of survivors.

Aldo Scimia, whose mother was killed, welled up as the verdict was read out.

"We cannot call this a victory. It's a tragedy, whatever way you look at it, it won't bring our loved ones back," he said.

"I continue to call this a massacre at the hand of the state, but at least now we hope that our children may live safer lives."

-- A historic legal precedent --

Some commentators had warned that any convictions would dissuade other experts from sharing their expertise for fear of legal retribution.

"We are deeply concerned. It's not just seismology which has been put on trial but all science," Charlotte Krawczyk, president of the seismology division at the European Geosciences Union (EGU), told AFP.

"All scientists are really shocked by this," said Krawczyk. "We are trying to organise ourselves and come up with a strong statement that could help so that the scientists do not have to go to jail."

The current INGV head Stefano Gresta also said the trial had set a legal precedent which would have serious repercussions across the science world.

"What scientist will want to express his opinion knowing that he could finish in prison?" he asked.

Filippo Dinacci, lawyer for the-then deputy director of the Civil Protection agency Bernardo De Bernardinis and its seismic risk office chief Mauro Dolce, said it was "difficult to understand" the verdict -- after criticising the charges last week as something out of "medieval criminal law".

The government committee met after a series of small tremors in the preceding weeks had sown panic among local inhabitants -- particularly after a resident began making worrying unofficial earthquake predictions.

Italy's top seismologists were called to evaluate the situation and De Bernardinis gave press interviews saying the seismic activity in L'Aquila posed "no danger".

"The ruling in my opinion is not fair. We will certainly be appealing," said Alessandra Stefano, lawyer for the head of the European centre of earthquake engineering Gian Michele Calvi.

Over 5,000 members of the scientific community sent an open letter to President Giorgio Napolitano denouncing the trial against colleagues for failing to predict a quake -- a feat widely acknowledged to be impossible.

"Seismologists are more or less reconciled to the fact that the chances of predicting when a large earthquake is going to strike are somewhat more remote than finding the Holy Grail," said Roger Musson at the British Geological Survey, calling the verdict "unbelievable".

The other defendants are Giulio Selvaggi, head of the INGV's national earthquake centre in Rome; Franco Barberi from Rome's University Three and Claudio Eva from the University of Genoa.

About 120,000 people were affected by the quake, which destroyed the city's historic centre and medieval churches as well as surrounding villages.

L'Aquila resident Ortense, whose sister was killed in the quake, said: "We didn't come here to get revenge, these men are all family men. But it does bring some comfort to know that someone will pay the price for misleading us."