SAN FRANCISCO — After six Italian scientists were sentenced to six years in prison for failing to warn the public of a devastating 2009 earthquake, experts are rethinking how they communicate risk.

The magnitude-6.3 earthquake hit the town of L'Aquila, Italy, on April 6, 2009, killing 309 people. A week prior to the quake, city officials had made reassuring statements that downplayed the risk, according to prosecutors, of a major quake linked to a series of smaller tremors. Prosecutors argued that the seismologists' risk analysis was flawed and that the statements made by city officials convinced residents not to evacuate, costing lives.

The group "got snookered into answering a simple yes or no question: Will we be hit by a large earthquake?" said Thomas Jordan, a researcher at the Southern California Research Center at the University of Southern California. "Seismologists can't provide an answer to that type of question."

The scientific community has been frightened by the possibility that seismologists could face criminal charges for failing to predict an earthquake — even though there's no way to truly forecast a temblor. [See Photos of L'Aquila Earthquake Destruction]

But the L'Aquila events have also forced hazard experts to reassess how they discuss risk with the public. For instance, scientists should actually state the numerical odds of a catastrophe striking, not rely on qualitative descriptions like "low chance," Jordan told LiveScience.

Downplaying risk

Prior to the quake, the quaint medieval town of L'Aquila had experienced a swarm of temblors. But in a press conference a week before the main earthquake, a city official (who was not a seismologist) said "the scientific community tells me there is no danger because there is an ongoing discharge of energy," reported Nature News.

That statement, which most experts think is not scientifically accurate, may have kept people from evacuating the town. The statement was a key part of the prosecution's argument that city officials and scientists were guilty of manslaughter, said Max Wyss, the director of the World Agency of Planetary Monitoring and Earthquake Risk Reduction.

Conveying the odds

So how should scientists communicate the odds of a cataclysmic event?

In 2008, Jordan and colleagues conducted a study that assessed the disaster protocols in six major countries known to have a lot of seismic activity. None of the countries had a formalized process to calculate earthquake probability and describe it to the public, he said.

Jordan and his team concluded that giving hard numbers is key: For instance, saying the odds of "the big one" are 1 in 100 or 1 in 10,000.

It's also important to compare the odds of an infrequent disaster with everyday risks that people are familiar with, such as a hurricane for people in the Caribbean, said Stephen Sparks, a volcanologist at the University of Bristol. People should also be told how much the odds of an earthquake or volcanic eruption have risen relative to the baseline, or normal seismicity in that area, he said.

But beyond that, seismologists need to convey the uncertainty in those estimates of probability, Jordan said.

"You actually have to deal with probabilities of probabilities," Jordan said. "That can be a technically difficult conversation."

5 Comments

1. 1. rshoff 07:22 PM 12/12/12

   I'm still trying to digest this. Are scientists really spending 6 years in prison because of the failure of public policy? Are the politicians going to jail too, because all things equal, they should. Were there underlying criminal actions that we're not aware of? This just cannot be true. Do the Italians still believe the world is flat and that science comes from a book of answers? Everybody who has been to junior high school should know that earthquakes are unpredictable and can happen at any time. So are hurricanes, tornados, tsunamis, etc, etc, etc.

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2. 2. alan6302 08:36 PM 12/12/12

   If something happens on dec 21, NASA will be in big trouble.

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3. 3. rshoff in reply to alan6302 08:47 PM 12/12/12

   Then we should throw them in jail now! We may not have the chance if we wait! ;-)

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4. 4. nissankananayakkara 06:36 AM 12/13/12

   Science still looks in its early stage while we are seeking solutions for most of the open questions notably in geology of this planet. So far Plate tectonics,progressing of space exploration as well have made us stunned last few years.The instruments planet having now are still to-be-improved stage.Exploration is to be going on until we find better predictions when the unknown crosses our path.Everybody living on this planet is a free thinker.

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5. 5. ErnestPayne 05:07 PM 12/13/12

   The geologists looked at the situation and went with the very high odds there would not be another event. They must know how Galileo felt.

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