Posted on behalf of Nicola Nosengo.

Public prosecutors in L’Aquila, Italy, have requested a four-year prison term for the six scientists and one government official charged with manslaughter after a magnitude-6.3 earthquake hit the city and its surroundings on 6 April 2009, killing 309 people (for more background on the case, read the Nature feature article ‘Scientists on trial: At fault?‘).

All those indicted took part in a meeting held in L’Aquila on 30 March, 2009, during which they were asked to assess the risk of a major earthquake in view of many shocks that had hit the city in the previous months. At the end of the meeting the Department of Civil Protection held a press conference where it downplayed the risk of a major quake and urged the population to stay calm. In particular Bernardo De Bernardinis, then deputy head of the department and among those indicted, said in a TV interview: “The scientific community tells me there is no danger because there is an ongoing discharge of energy”, a statement that most seismologists consider to be scientifically incorrect. According to the relatives of some victims and to the prosecutors, those reassurances prompted many people not to evacuate, hence the manslaughter charge (See ‘Italy puts seismology in the dock‘).

The trial began a year ago, on 20 September 2011 (See ‘Scientists on trial over L’Aquila deaths‘), and has proceeded at an unusually fast pace (by the standards of the Italian judicial system), with an average of one hearing per week. The prosecution’s closing arguments lasted from Monday morning until Tuesday afternoon, and were shared between two prosecutors, Fabio Picuti and his assistant Roberta D’Avolio. Picuti made it clear that the scientists are not accused of failing to predict the earthquake. “Even six-year old kids know that earthquakes can not be predicted,” he said. “The goal of the meeting was very different: the scientists were supposed to evaluate whether the seismic sequence could be considered a precursor event, to assess what damages had already happened at that point, to discuss how to mitigate risks.” Picuti said the panel members did not fulfill these commitments, and that their risk analysis was “flawed, inadequate, negligent and deceptive”, resulting in wrong information being given to citizens.

Picuti also rejected the point – made by the scientists’ lawyers – that De Bernardinis alone should be held responsible for what he told the press. He said that the seismologists failed to give De Bernardinis essential information about earthquake risk. For example, he noted that in 1995 one of the indicted scientists – Franco Boschi, former president of the National Institute for Geophysics and Vulcanology (INGV) – had published a study that suggetsed a magnitude-5.9 earthquake in the L’Aquila area was considered highly probable within 20 years. Similarly, said that in 2009 INGV’s maps of seismic risk estimated the probability of a magnitude 5.5 shock in the following decade to be as high as 15%. Such data were not discussed at the meeting, as the minutes show.

“Had Civil Protection officials known this, they would probably have acted differently,” said Picuti. “They were victims of the seismologists”.

Claudio Eva – a professor of physics at the University of Genoa who is among the indicted – said after the hearing that he had been expecting the request for a four-year sentence. He declined to comment further, as did the others.

The defence will present its closing arguments on 9 and 10 October, and the court’s decision is expected on 23 October.