Chris De Freitas: Inaccurate prediction more harmful than no prediction

Knowledge of the past is an important ingredient of any recipe for predicting the future. Photo / Ben Fraser

Opinion

The past few years have not been great for those in the business of predicting natural disasters. Think of the doomsday forecasts of Christian radio broadcaster Harold Camping and that of the much hyped Mayan calendar.

New Zealand disaster experts have been better at their predictions, though we don't know by how much - think Christchurch.

Six years in jail and an average fine of over $1 million was the punishment given to six Italian scientists late last year for getting their earthquake advice wrong.

So what will our expert geologists and vulcanologists say the next time they are asked about the likelihood of an earthquake or volcanic eruption?

Knowledge of the past is an important ingredient of any recipe for predicting the future. There are many reminders: Christchurch most recently, the big Wellington quake 158 years ago and the large Napier earthquake 70 years later. Mt Ruapehu has erupted 10 times in the past 150 years. But prediction of such events is problematic.

The Italians were found accountable for multiple cases of manslaughter. The court alleged the men were guilty because they failed to give an adequate risk assessment of a magnitude 6.3 earthquake near the Italian town of L'Aquila, which killed 309 people in April 2009.

At the heart of the case was the claim that 29 of those who died had considered leaving L'Aquila, but they were influenced to stay by statements the scientists were suspected of making. On the one hand tremors and radon emissions from the earth in the locality were seen as precursors to a serious earthquake event; on the other, as a manifestation of an ongoing release of energy and a basis for denying the likelihood of a serious event.

One assumes that science-based predictions are objective. But prediction for risk assessment is as much an art as it is a science.

The lesson to be learned from the Italian court decision is in the disaster that science brought upon itself. Sometimes scientists invest too much of their credibility in one side of an issue.

On the other hand, the problem might have been poor risk communication. Quality risk communication involves providing the public with information necessary to minimise injury, loss of life and property damage.

Fear of outcomes such as illustrated by the Italian court case may inspire scientists to take a more precautionary route. No matter how small the assessed risk, they will be inclined to "predict" a possible occurrence of a hazard event.

The public deserve objective information and they will resent the costs of false alarms.

It is necessary to consider the social and economic impact of the prediction itself. If we were confident in our prediction, dangerous buildings could be knocked down. It is likely that a large number of people would move away, businesses would shut down, and the local economy would probably go into decline.

An inaccurate prediction can have worse consequences than if there had been no prediction at all.

To be useful, a prediction needs to include a correct estimate of the earthquake's magnitude, location and time of occurrence. As this is not possible, the focus should shift to adaptation. We have the knowledge and skills to reduce the impacts of such events.

Many natural hazard professionals consider the key to reducing losses is to implement measures that increase community awareness, readiness and resilience. The emphasis needs to be on dealing with the social, political and economic impediments that prevent effective disaster risk reduction.

Associate Professor Chris de Freitas is a geographer in the school of environment at the University of Auckland.