Week in Review

How much risk is too much?

White Island tour operators have said that the eruption risk level on the island yesterday was within their guidelines to keep operating.

Yet when tragedy strikes, it’s natural to question whether the powers that be made the right decisions. It's important to remember that people assess risks, and decide to take them, every day, says David Johnston, a senior scientist at GNS and Professor of Disaster Management at Massey University’s School of Psychology.

Newsroom: The tragedy at Whakaari-White Island has got people talking about whether we struck the right balance in assessing the risk of an eruption. I don’t expect you to comment on the specifics of that yet, but, generally speaking, how do we make these decisions?

Professor Johnston: We assess risks from a range of natural and other hazards in New Zealand. There are various statutes we manage the risk through, such as our Health and Safety legislation, and those do indirectly cover volcanoes, including the risk to employees. The tour companies needed licences for operating and it’s already been reported that there was a Memorandum of Understanding in place for White Island. (The MOU is between the Government and the Bay of Plenty Civil Defence Emergency Management Group and covers who will respond to an eruption.)

Then we also have the volcano alert levels. We separate the scientific risk assessment from the decision-making around the actions that people take. So, it’s not the scientists who close off things or allow things, the police do that based on advice from technical experts, not just experts on volcanoes but in health and other areas.

Newsroom: We’ve seen in this case that GNS has raised and lowered its volcano alert levels for White Island over time. It will raise it to a 2, then put it down to 1, then back again. How do people make decisions with that information? Because it seems like there is always some level of risk.

Professor Johnston: Yes, and that’s reflected in the (emergency) plans. If you leave aside volcanoes for a minute and think about avalanches, it’a similar scenario. They (scientists) are doing risk assessments all the time. The ski industry is a good analogy because there are a whole lot of safeguards in place and a whole lot of training, and but you still have avalanches. There is a duty of care, but things happen. Volcanoes and ski fields operate under similar legal and regulatory frameworks.

Newsroom: It’s tempting at awful times like this to think, we should never have taken that risk. Are some activities inherently risky?

Professor Johnston: There is a lot of literature about how people perceive risk. There are tensions between state and individual rights in lots of settings. In 1973 when we introduced seat belts there was great lobbying against that, and we saw it with bicycle helmets and speed limits too. I want to stay away from the volcano decision because obviously there’s going to be a review, but you can see parallels in many of the risk decisions we make in society. How do you make those calls? Sometimes, we were slow. We killed 800 people on the roads in the 1970s and we then decided we should do something about it. There are always hard decisions made.

Newsroom: Is there a correct level of risk?

Professor Johnston: Acceptable risk is a social construct because the question is, acceptable to who? An example was the Port Hills assessment for rockfalls and whether houses should be red zoned or not (after the Christchurch earthquakes). There was a formal process of assessing risk, however, the process was highly contested and someone had to make a call about what was safe and not safe. They went through a lengthy scientific process, but even then it is just opinions.

Newsroom: Another example that’s geographically close to White Island is Matata, where the experts are saying there’s a risk of deadly flooding and they need to move the houses. And some of the residents are saying 'No, you're wrong, we don't want to go'.

Professor Johnston: Until maybe after an event, and then they will say 'Why didn’t we?'. Hindsight is always useful. Because our decision-making is so much shaped by context and experience, often people are not looking at it from all directions, and how can you, if you don't have experience of [a danger]? Pike River also raised many of these questions. We make very complex risk decisions, and there are often multiple trade-offs and it's very hard to get a simple answer. It’s quite subjective. Simultaneously, people will say we overestimate a risk and others will say we underestimate a risk, on the same hazard. We’ve got to be comparable. We let people drive to the ski field but should we stop them from skiing? It’s actually more dangerous on the road to the ski field than at the ski field. We have a high tolerance in certain domains. I don’t think anyone would seriously propose banning vehicles because they allow us to live our lives as we do.

Newsroom: What will be considered in the review of the White Island tragedy?

Professor Johnston: They will look at the long-term risk assessment, as well as the immediate response to it. That’s how society learns, and I think the public will expect a review. It’s too early to call, but I think we will be asking 'Was this risk acceptable and at what thresholds?'.

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