The Basic Facts
In October 2008, the city of L’Aquila in Italy began experiencing earth tremors. Given that the city has been pretty much destroyed by earthquakes twice in the past, this was a matter of some concern. For the next six months the tremors continued. On March 31 the National Committee for the Prediction and Prevention of Major risks had a meeting, and a civil service spokesman re-assured the public that there was no immediate danger. Within a week, more than 300 people were killed when a major earthquake struck.
Seven members of the National Committee were charged with manslaughter for providing the public with information that was “inexact, incomplete and contradictory”, and on Monday this week they were sentenced to jail terms of six years. There are many misleading summaries of this case available, perhaps because of the tangential prosecution and defence cases. The defence, both in court and in public maintained that it was not reasonable to expect scientists to predict the timing of an earthquake. However, that isn’t what the prosecution was alleging. The prosecution case was that the scientists didn’t communicate the risk appropriately. According to the prosecution, at least 29 of the victims stayed in an unsafe situation due to receiving misleading information about the risk they faced.
Two news stories with accurate portrayal:
There are three underlying questions here:
1) Can you do risk estimation for an earthquake?
2) How should you communicate risk information of this sort?
3) Should you get six years in jail if you do either of these incorrectly?
Risk Estimation for Earthquakes
Unlike most infrequent high-consequence events, the risk of an earthquake in certain areas does build up over time. So while it is nonsense to say that we are “overdue” for a big storm, a flood, or a stock-market crash, it does actually make some sense to say that an area is overdue for an earthquake. These are still low probabilities though – for example, Southern California is waiting for the next big one, meaning that there’s around a 2% chance of a major quake in the next thirty years.
Most earthquake science is focussed on modelling what’s likely to happen during an earthquake, rather than when the earthquake will come. This make sense, because the most effective protective measures are long-term anyway: Good building design; removing or protecting buildings built before the modern building codes; and teaching people appropriate earthquake behaviour. By understanding the range of scenarios that are likely or possible, we can put appropriate protection in place.
As far as short-term prediction goes, big earthquakes do often have fore-shocks – smaller movements leading up to the highest energy event. These can, on a scale of a few minutes to a couple of days, give warning of increased risk. There is a lot of uncertainty involved, and it’s an area where more research and more computer power may be able to improve predictions in future. At the moment, it’s akin to clouds as a predictor of rain. You aren’t totally safe if the sky is clear, and seeing clouds doesn’t tell you that it’s going to rain, but looking at the sky does help you determine the odds.
The Southern California Earthquake Center has good general information on earthquake modelling, as well as a handy guide to living in an earthquake-prone area.
Risk communication is a whole scientific field in its own right, with a compelling message that it isn’t enough to simply tell the truth about risk, you have to tell it in a way that people can make sense of. An Australian earthquake expert Professor Paul Somerville said that the Italian team had a case to answer because of the way they communicated. As far as I can tell from the news reports though, his answer is that the scientists should stick to reporting numbers and let society do the interpretation. This isn’t what the research on risk communication suggests.
The archetypical example is doctors telling patients about the risks of treatment. Simply quoting numbers like one in a thousand or one in ten-thousand patients experiencing a side-effect is meaningless without context. Patients can’t make useful sense of these numbers. Comparisons instead or as well are often very useful. “This drug is about as dangerous as panadol, and much safer than doing nothing”; or “There is a small chance that this drug will make things worse – about the same chance as you being in a car accident in the next year”.
One consistent result in risk communication research is that deliberately being inaccurate in order to reassure people doesn’t work. The situation in Italy was complicated by scare-mongering by various parties, including one seismic technician giving warnings through a megaphone. The scientists rightly thought that it was important for people to have a realistic view of the risk. With hindsight, it’s easy to put better words in their mouths such as “The tremors are a sign of increased risk, but they don’t tell us whether or not a big earthquake is about to happen. Citizens should, as always, make sure that they have followed the steps in the earthquake preparedness booklet, and know what to do if an earthquake does happen”.
The work of Professor Terje Aven at University of Stavenger is a good starting point for reading about risk and risk communication.
Jail for Poor Risk Communication?
Personally, I think that not being able to properly communicate the risk of a major hazard is a pretty big deal when your job description is to communicate the risk of major hazards. The committee deserved to be dragged over the proverbial coals whether or not the earthquake happened.
Drawing a causal link between their inept communication and people dieing is another thing altogether. It’s easy to say afterwards that person X would not have stayed in their shaky house if they’d known the true risk. That’s rather hard to prove though, given that people were living in poor housing in an earthquake zone for months and years. Yes, some people might have skipped town for a couple of days, but that wouldn’t have been a rational response to the risk. Those same people would still have been killed if the earthquake happened a week later, or two weeks later, or a month later.
Essentially, the court has found that a combination of proper risk communication, irrational response, and good luck, would have saved lives, therefore the scientists are at fault. Hopefully, they win their appeal. I don’t think that this will have a chilling effect however. I hope and believe that this will make more scientists realise that communication is an important part of their role, and requires as much care and attention as the research itself.
The Professor Paul Somerville interview is here.