Monday, October 29, 2012

Prison Terms for Careless Words: The L’Aquila Seismology Verdict

Suppose you are a citizen of the medieval Italian town of L’Aquila.  Your city has survived several earthquakes in its history, including ones that led to considerable loss of life in 1461 and 1703.  In late March of 2009, you notice that there have been small tremors lately that perhaps rattle a dish or two, but this is nothing particularly unusual in highly seismic Italy.  However, a lab technician in a town thirty miles away garners some publicity when he announces that a method he’s come up with to predict earthquakes is telling him there’s going to be a big one soon.  You wonder whether it will be worth the trouble to sleep outside, which is something you have done on occasion when the temblors get severe.

Then you tune in to a news report of an announcement by a seven-member expert commission made up of seismologists, engineers, and a government official.  The panel’s conclusion is that the tremors over the past four months pose “no danger.”  In fact, one of the panelists says that “in fact it is a favorable situation, that is to say a continuous discharge of energy.”  This makes you feel better, and you decide to continue sleeping indoors.

Six days later, at 3:30 in the morning on April 6, a 5.8-magnitude earthquake hits L’Aquila.  You survive, but many people are killed, about 300 in all, and hundreds of buildings of both medieval and modern construction either collapse or are severely damaged.  Now the question:  what should be done about that panel of experts?

The Italian legal system has answered that question.  On Oct. 22 of this year, all seven members of the panel were convicted of manslaughter and sentenced to six years in prison.  This verdict has made headlines around the world for a number of reasons.

Italian prosecutors insist that the scientists and engineers are not being charged with failing to predict the earthquake.  Everyone (or nearly everyone) acknowledges that earthquake prediction is still an inexact science compared to weather forecasting, for instance.  But except for relatively rare fatal storms such as hurricanes and tornadoes, one’s life does not depend on the accuracy of a weather forecast.  The government prosecution contended that the panel’s reassurances that the temblors did not mean an earthquake was imminent, prevented L’Aquila residents from sleeping outside and thus led to a larger number of deaths than if they had kept quiet.

For the convicted scientists and engineers, things may not be quite as bad as they seem.  On average, in Italy about four out of five convictions involving prison terms are never put into effect, due to reversals on appeal or other reasons.  Nevertheless, these convictions are a sobering warning to experts who make public pronouncements about the possibility of earthquakes.

An article on the conviction in The Economist carried the subhead “Damned if you do, damned if you don’t.”  Earthquake experts asked to predict quakes face a classic dilemma.  If they fail to predict an earthquake that occurs, they can be charged with negligently giving bad advice that led to fatalities, at least in Italy.  But if they go to the other extreme and sound the alarm any time it looks like a quake might happen, they are liable to cause panic, or else to be wrong so often that people will ignore them even when they turn out to be right.  The independent prediction by the lab technician that his radon-based method was saying an earthquake was coming caused panic in a nearby town, and it is possible that the L’Aquila commission felt obliged to calm troubled waters.  It was their bad fortune to take that position less than a week before the fatal quake that did happen.

While the U. S. has perhaps a more robust tradition of free speech, including the freedom to give opinions about public dangers without worrying about manslaughter charges, the unhappy experience of the Italian earthquake scientists and engineers is a cautionary tale for any expert who makes public pronouncements on matters relating to safety.  Despite appearances, people do listen to experts and sometimes even take their advice.  I am not aware of any doctors from the 1950s who were quoted in TV ads as saying smoking was harmless, and then were sued or charged with manslaughter after it was shown that cigarettes cause cancer.  But that may be because a powerful industry fought the idea for decades.  No well-funded interest group had a vested interest in showing that the scientists had science on their side when they dismissed the possibility of an imminent quake.  Other members of the Italian National Institute of Geophysics and Vulcanology (NIGV) did some Monday-morning quarterbacking after the quake and calculated that the chances of a big earthquake happening in the 10-km region around the city rose from a normal background of 1 in 200,000 to a much greater, but still small, chance of 1 in 1000 a few hours before it actually occurred.  But one chance in a thousand is still a pretty long shot, and even if the panel had announced this relatively great increase in the likelihood of an earthquake, they might still have found themselves in the dock.

Part of the problem is that most average citizens do not want to deal in probabilities.  They want to know, “Are we going to have an earthquake or aren’t we, and if so, when?”  Unfortunately, the science we have so far can only deal in probabilities, and if experts are asked to give more than raw statistics about a possible future event, they tend to send a message that is either reassuring or alarming, depending on the tone of the situation and any number of other extraneous factors.

Let us hope that the Italian convictions don’t persuade seismologists to eschew forecasting as too personally risky to engage in, because a robust and reliable science of earthquake forecasting would be a valuable thing that could save lives.  But if earthquake scientists feel that they are putting their personal lives and liberty at stake every time they issue an opinion, the science and engineering pertaining to earthquakes could itself suffer long-term damage as an unexpected casualty of the L’Aquila disaster.

Sources:  Besides the two articles in The Economist on the seismologists’ trial (one on Sept. 17, 2011 after the indictment at
and the second on Oct. 27, 2012 at, I used an article on the Italian legal system at, and I referred to the Wikipedia articles “Italian Code of Criminal Procedure” and “2009 L’Aquila earthquake.”

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