White Island recovery effort hampered by toxic gases and eruption risks
Tuesday, 10 December 2019
Toxic gases and small eruptions are now confronting rescuers planning the recovery of eight tourists killed on Whakaari/White Island.
The volcanic island erupted on Monday afternoon, spewing ash into the air, killing five tourists and injuring 31.
A recovery operation is now being planned. Police on Tuesday confirmed eight people remained on the island, but reconnaissance flights had seen no sign of life.
The risk of another eruption is great, but there are other risks the rescuers are having to weigh up in deciding when to land on the island.
**READ MORE:
* A history of White Island eruptions
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* How will volcanic eruption affect the rest of New Zealand?**
University of Auckland professor Shane Cronin said volcanic activity at Whakaari/White Island may not settle for weeks, or months.
After the eruption, magma beneath the surface continued to release hot water and gases into the 'jumbled mess' of rock that had again settled in the crater.
'The gas is trying to find new pathways out through that jumbled mess … You get build ups of smaller gas pockets that will then also explode and generate similar but, probably, smaller eruptions,' he said.
The landscape would be strewn with rock deposits and difficult to move around.
As poisonous sulfur dioxide and hydrogen sulfide were released, movement across the island would be made further difficult by the breathing and protective gear rescuers may have to wear.
'If they are looking for deceased victims, they're going to be buried [under] a large amount of tephra and rock material,' Cronin said.
On Tuesday afternoon, police said it would continue to work with GNS scientists to evaluate the risk of further eruption, 'as well as any risks posed to recovery teams by gases in the atmosphere'.
GNS Science issued a statement which said there was a 50 per cent risk of another eruption.
Scientists flying over the volcano would be measuring the amount of gas being emitted from the crater, Cronin said.
More gas than usual could mean the magma is closer to the surface, and an eruption was more likely.
But less gas could mean it was trapped beneath the surface, which could also lead to an eruption.
'There's never a straight answer for any of these things,' he said.
Cronin had visited Whakaari/White Island numerous times and participated in similar risk assessments to those happening now.
He said during such evaluation, everyone involved is told the latest information from the volcano and 'robustly' discusses what should be done.
'You basically each cast a vote on what you think is the best response … consensus is built, and if there's a big difference of opinion then you go back to the discussion,' he said.
Massey University professor David Johnston, an expert in disaster management who formerly worked at GNS for more than two decades, said an eruption had been planned for.
'There had been a formal risk assessment and emergency management response plan in place,' he said.
A Bay of Plenty Civil Defence and Emergency Management plan from 2018 shows volcanic activity on Whakaari/White Island was assessed as being the fourth most risky hazard in the region.
Tsunamis, both local and distant, and a human pandemic were considered a higher risk.
Johnston said it was for GNS to provide information about current volcanic risk to agencies and companies, including civil defence and tour operators.
Agencies and companies would then make their own risk assessment.
This separation of advice and decision-making protected 'free and frank advice', he said, and was an arrangement that had developed over years.
'One would go to look at what happened and see whether the system was was robust or not, but that's in the fullness of time,' he said.
Johnston said it appeared the disaster response was being well managed.
New Zealand's response to such disasters had been reviewed a number of times since the 2011 Christchurch earthquake, he said.
The country had seen a number of disasters in recent years, including the Pike River Mine explosion in November 2010, the Kaikōura earthquake in 2016, severe flooding in Edgecumbe in 2017, and the mass casualties of the March 15 terror attack.
'Sadly as a nation we're getting more and more prepared for such things,' Johnston said.