In October 2012, six Italian scientists and one government official were found guilty of the manslaughter of 29 people who died during the 2009 L'Aquila earthquake. Each was sentenced to six years in prison. When the case was first opened, geological societies rushed to the aid of the scientists — a natural reaction to their colleagues being under attack. However, as disaster risk scientist David Alexander argued in a seminar at University College London in January 2013, on closer inspection of the trial and the evidence presented, there could be a case for negligence.

Importantly, the levy against the accused was that of failing to adequately evaluate and communicate risk and presenting falsely reassuring findings to the public, not of failing to predict the quake, as was often assumed after the trial was announced. Comments made by Bernardo De Bernardinis, the government official on trial and deputy head of Italy's Civil Protection Department at the time, could be interpreted as falsely reassuring. Before the earthquake, De Bernardinis stated publicly that ongoing seismic tremors affecting L'Aquila posed no danger, and that the scientific community continued to confirm to him that the situation was favourable. During the trial, several witnesses testified to say that comments from officials lulled the community into a false sense of security. According to the prosecution, some people remained in their homes while the ground shook, whereas ordinarily they would have evacuated, and were killed when the buildings collapsed (Science 338, 184–188; 2012).

The case for inadequate evaluation and communication of risk by the scientists is less obvious. The scientists had explained to the officials that numerous seismic swarms in the past hadn't culminated in large earthquakes and the probability of one on this occasion was low (Science 338, 184–188; 2012). This assessment and communication to the officials seems fair. Why then did the scientists not publicly step forward to correct the overly reassuring statements made by De Bernardinis and to reiterate that there was still an ongoing possibility, even if slim, of an earthquake? Earth scientists should know that the communication of hazard assessments requires utmost care and attention to uncertainty, yet it seems that these scientists didn't speak directly to the public at any point. Perhaps they should have done.

Whether there is a case for negligence or not, the charge of manslaughter is extreme. Such a severe sentence will make scientists hesitant to advise and is unlikely to improve communication. To avoid similar shortfalls in the future, we should focus on equipping Earth scientists with adequate communication skills, and heighten their understanding of how their words — or those of government officials speaking to the public on their behalf — will be perceived. Risk communication and media training are common in many fields: doctors, athletes and even models are groomed on how to deliver an appropriate response during press interrogation.

Earth scientists inform on life-or-death situations, from impending volcanic eruptions and seismic hazards, to flood or tornado warnings and climate change. It is vitally important that those with hazard-related expertise learn and practice early on how to phrase recommendations so that the public gets the right message.