The head of Italy's disaster body, Luciano Maiani, has resigned in protest at prison sentences passed on seven colleagues over the 2009 earthquake in L'Aquila.
Six scientists and an ex-official were convicted of multiple manslaughter for giving a falsely reassuring statement.
Prof Maiani, a physicist, said the Serious Risks Commission could not work "in such difficult conditions".
The 6.3-magnitude quake killed 309 people and left the city in ruins.
Prof Maiani's decision to quit was announced by the Italy's Civil Protection Department, which said the commission's vice-president, Mauro Rosi, and emeritus president Giuseppe Zamberletti had also tendered their resignations.
"The situation created by yesterday's sentence... is incompatible with running the commission's work in a calm and efficient manner and with its role of giving high level advice to the organs of the state," Mr Maiani said in a statement on the department's website.
"A scientific committee has to give in its own judgement... The advice may be wrong. Or it may be imprecise. But if you have such a heavy punishment the committee will not act properly," he later told the BBC's Newshour.
"A committee will tend to be, always, on the very, very conservative side. I think there is a definite danger that scientific communities will refrain from giving advice to the government."
Prof Maiani, a world-renowned physicist who was director general of the Cern nuclear research centre in Switzerland from 1999-2003, said the possibility of being judged for your scientific judgement was a "serious problem".
"In this condition, and with this precedent, I would not take the job," he added.
'Perverse and ludicrous'
The group, all members of the National Commission for the Forecast and Prevention of Serious Risks, were accused of having provided "inaccurate, incomplete and contradictory" information about the danger of the tremors felt ahead of the 6 April 2009 quake.
At a meeting a few days before the deadly quake, they had told officials in L'Aquila that, while a major earthquake was not impossible, it was not likely.
On the night of the quake, many people are said to have remained in their homes and died because of the advice, while others who had decided to remain outside in the street survived.
In their closing statements at the trial in L'Aquila on Monday, prosecutors quoted a witness whose father had died.
Guido Fioravanti called his mother 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."
However, the six-year jail sentences have shocked the scientific community.
The prestigious science journal, Nature, said "the verdict is perverse and the sentence ludicrous". It called for protests against the sentence's severity and at scientists being criminalised "for the way their opinions were communicated".
Leading political figures in Italy suggested that the case had blurred the lines between science and public life.
"The risk is that doubt will no longer be allowed to form part of scientific judgement," Interior Minister Anna Maria Cancellieri said. "The role of science is not the same as politics or administration."
The speaker of the lower house of the Italian parliament, Gianfranco Fini, was more blunt in his assessment of the verdict: "I trust it will be corrected on first appeal."
Among those convicted are some of Italy's most prominent and internationally respected seismologists and geological experts.
Their defence had called for their acquittal, arguing that it was impossible to predict an earthquake. More than 5,000 scientists said the same thing when they wrote an open letter to Italian President Giorgio Napolitano in support of the men in 2010.
Reacting to the verdict against him, Bernardo De Bernardinis, former vice-president of the Civil Protection Agency's technical department, said: "I believe myself to be innocent before God and men."
While the seven men involved are appealing against their convictions - and remain free while they do so - all are facing the prospect of being barred from ever holding public office again.