Preparing for the big one on the Alpine Fault

Friday, 17 March 2017

Urgent national planning for a devastating magnitude-8.2 rupture of the Alpine Fault is underway with a formal plan to be released next year.

In meeting rooms across the South Island hundreds of people have been talking about a disaster high in the mountains above.

They've never met before, but they'll be on the front-line when it happens. They need a plan.

These are the authorities who have spent recent months developing a coordinated response to a disaster of unprecedented scale in New Zealand, and likely happen in the near future.

**READ MORE:

*** Magnitude-8.2: A disaster scenario

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* Southland families urged to plan a meeting place in case of a natural disaster

* Environment Southland receives $245k grant for Alpine Fault research

* Are we ready? What to expect when the Alpine Fault ruptures

* Alpine Fault moves more than any other land fault

* Alpine fault could isolate West Coast for six weeks

* Scientists digging into new part of Alpine Fault

While the fault has been known about for many decades, as has its destructive impact, preparing a response has only become urgent recently.

The latest incarnation is Project AF8 (Alpine Fault 8), a partnership between the South Island's disaster management groups.

The project is funded by the Ministry of Civil Defence & Emergency Management and will culminate in a formal plan, set for release next year.

Workshops throughout the country have joined hundreds of people from dozens of agencies, thinking about the nearly endless possibilities arising from an earthquake in the mountains and how to respond.

The scenario posits an earthquake of an 8.2 magnitude, centred near Haast, with a rupture length of approximately 400km.

The energy released would be four times that of the Kaikoura earthquake, and 700 times that of the 2011 Christchurch earthquake.

It could be felt as far away as Sydney and have a major impact the length of the South Island with thousands of landslides, the damming of major rivers and tsunamis on inland lakes.

It's one scenario of many, which makes planning such a difficult task.

'What we learned from the Kaikoura quakes is you have to expect the unexpected,' said Dr Caroline Orchiston, science leader of Project AF8.

'I don't think the science community would have expected that complex sequence of events, of there being multiple ruptures on multiple faults simultaneously.'

There's generally high public awareness of earthquake hazards following Canterbury and Kaikoura.

It has prompted deeper thinking about the Alpine Fault, long-known to be the most dangerous hazard of all, but rarely thought about in great detail.

But that has changed recently.

Research has looked at the threat of rockslides and tsunamis, the impact of tourism, the individual communities likely to be isolated.

Pulling this together, along with the work of numerous scientist and disaster management experts, has concentrated more knowledge about what to expect than ever before.

'We've come a long way in 10 or 20 years, for sure,' Orchiston said.

'There's no point burying your head in the sand. We have to start thinking about it.'

While the scientific community has broad agreement on the threat posed by the Alpine Fault, it hasn't always transferred to the communities most affected.

Late last year, the Westland District Council removed a fault avoidance zone from Franz Josef.

The zone prevented development on the fault, which runs through the town.

Orchiston was one of four University of Otago scientists who urged the council in a letter to keep the restriction.

They said the town faced the likelihood of 'significant loss of life and property within the township during our lifetimes.'

'It's a real tragedy that's been removed, in my opinion,' she said.

'It's one of the big challenges with any natural hazard planning. There's a lot of politics and human behaviour involved in it, you can't just dictate what's going to happen based on what the risks are.'

When the time comes, each region will effectively be alone, presenting a huge coordination challenge.

Electricity will be down, as will most forms of communication.

Building the relationships between regions beforehand had been crucial, said Project AF8 programme manager Jon Mitchell.

'It is a significant coordination challenge, that's for sure,' he said.

'There are people from agencies who have never met before, who would need to in any significant emergency response. That in itself has been extremely valuable.'

The disaster will present problems impossible to plan for.

But getting everyone together to plan what they could control was a start.

'We will continually have to do better. But this project gives us an opportunity to focus on doing that, in some parts better than has been the case before.'