Six Italian scientists and an ex-government official have been sentenced to six years in prison over the 2009 deadly earthquake in L'Aquila.
A regional court found them guilty of multiple manslaughter.
Prosecutors said the defendants gave a falsely reassuring statement before the quake, while the defence maintained there was no way to predict major quakes.
The 6.3 magnitude quake devastated the city and killed 309 people.
Many smaller tremors had rattled the area in the months before the quake that destroyed much of the historic centre.
It took Judge Marco Billi slightly more than four hours to reach the verdict in the trial, which had begun in September 2011.
Lawyers have said that they will appeal against the sentence. As convictions are not definitive until after at least one level of appeal in Italy, it is unlikely any of the defendants will immediately face prison.
The seven - all members of the National Commission for the Forecast and Prevention of Major Risks - were accused of having provided "inexact, incomplete and contradictory" information about the danger of the tremors felt ahead of 6 April 2009 quake, Italian media report.
The Apennines, the belt of mountains that runs down through the centre of Italy, is riddled with faults, and the "Eagle" city of L'Aquila has been hammered time and time again by earthquakes. Its glorious old buildings have had to be patched up and re-built on numerous occasions.
Sadly, the issue is not "if" but "when" the next tremor will occur in L'Aquila. But it is simply not possible to be precise about the timing of future events. Science does not possess that power. The best it can do is talk in terms of risk and of probabilities, the likelihood that an event of a certain magnitude might occur at some point in the future.
The decision to prosecute some of Italy's leading geophysicists drew condemnation from around the world. The scholarly bodies said it had been beyond anyone to predict exactly what would happen in L'Aquila on 6 April 2009.
But the authorities who pursued the seven defendants stressed that the case was never about the power of prediction - it was about what was interpreted to be an inadequate characterisation of the risks; of being misleadingly reassuring about the dangers that faced their city.
Nonetheless, the verdicts will come as a shock to all researchers in Italy whose expertise lies in the field of assessing natural hazards. Their pronouncements will be scrutinised as never before, and their fear will be that they too could find themselves embroiled in legal action over statements that are inherently uncertain.
In addition to their sentences, all have been barred from ever holding public office again, La Repubblica reports.
In the closing statement, the prosecution quoted one of its witnesses, whose father died in the earthquake.
It described how Guido Fioravanti had called his mother at about 11pm on the night of the earthquake - straight after the first tremor.
"I remember the fear in her voice. On other occasions they would have fled but that night, with my father, they repeated to themselves what the risk commission had said. And they stayed."
The judge also ordered the defendants to pay court costs and damages.
Reacting to the verdict against him, Bernardo De Bernardinis said: "I believe myself to be innocent before God and men."
"My life from tomorrow will change," the former vice-president of the Civil Protection Agency's technical department said, according to La Repubblica.
"But, if I am judged by all stages of the judicial process to be guilty, I will accept my responsibility."
Another, Enzo Boschi, described himself as "dejected" and "desperate" after the verdict was read.
"I thought I would have been acquitted. I still don't understand what I was convicted of."
One of the lawyers for the defence, Marcello Petrelli, described the sentences as "hasty" and "incomprehensible".
The case has alarmed many in the scientific community, who feel science itself has been put on trial.
Some scientists have warned that the case might set a damaging precedent, deterring experts from sharing their knowledge with the public for fear of being targeted in lawsuits, the BBC's Alan Johnston in Rome reports.
Among those convicted were some of Italy's most prominent and internationally respected seismologists and geological experts.
Earlier, more than 5,000 scientists signed an open letter to Italian President Giorgio Napolitano in support of the group in the dock.
After the verdict was announced, David Rothery, of the UK's Open University, said earthquakes were "inherently unpredictable".
"The best estimate at the time was that the low-level seismicity was not likely to herald a bigger quake, but there are no certainties in this game," he said.
Malcolm Sperrin, director of medical physics at the UK's Royal Berkshire Hospital said that the sentence was surprising and could set a worrying precedent.
"If the scientific community is to be penalised for making predictions that turn out to be incorrect, or for not accurately predicting an event that subsequently occurs, then scientific endeavour will be restricted to certainties only and the benefits that are associated with findings from medicine to physics will be stalled."
Não conheço muito bem os contornos da história, mas fiquei