Queenstown conference told of potential impact of alpine fault rupture

Friday, 14 October 2016

Geologists have indicated another big quake on the Alpine Fault is due.

An earthquake triggered by a rupture in the Alpine Fault would be like 'Christchurch on steroids', an emergency management conference has been told.

About 50 emergency-related organisations from across the country were introduced to Project AF8 [Alpine Fault Magnitude 8], a group set up to 'collectively plan for an Alpine Fault event'.

University of Otago scientist Dr Caroline Orchiston addresses an emergency management conference in at the Copthorne Hotel and Resort in Queenstown on Friday.

The talk was part of the South Island Civil Defence Emergency Management Conference held at the Copthorne Hotel and Resort in Queenstown on Friday.

Emergency Management Southland manager Angus McKay said an Alpine Fault rupture and resulting earthquake would 'change life in New Zealand'.

The Alpine Fault scarp crosses fields near Haast before heading southwest into isolated country and finally going out to sea at the mouth of Milford Sound.

Franz Josef sits right on top of the alpine fault. The scarp runs through the township and can be seen here tracking across a road and underneath motels.

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'If you thought Christchurch [earthquake] was bad, that's Christchurch on steroids. It's going to change the way of life.'

About one million people visited Milford Sound annually and 30 per cent of all international visitors went to Milford Sound, the closet human habitation point to the Alpine Fault's likely rupture point, McKay said.

'When the Alpine Fault pops, there won't be a Milford Sound anymore,' he said.

'After two years, we're hoping to have a South Island Emergency Response Plan for the Alpine Fault. If we don't get this right, we're not serving our people.'

The Project AF8 funding of $245,000 was part of the Government's annual $889,000 Civil Defence and Emergency Management's Resilience Fund announced in June.

Project AF8 science liaison Dr Caroline Orchiston from the University of Otago, said the fault had the potential to 'pop off a big one [earthquake] pretty soon', but with research data from as far back as 1770AD, the group hoped to be able to prepare people for it.

When an earthquake did occur along the Alpine Fault, the damage would be widespread as the fault 'is going to unzip basically', Orchiston said in a phone interview.

'Queenstown would be badly affected but so would other places across the South Island.'

The central and southern parts of the Alpine Fault run for about 400 kilometres up the spine of the South Island, and are about 40 times longer than the fault responsible for the fatal February 2011 earthquake in Christchurch.

GNS science said in May there was a 30 per cent chance of a large earthquake on the Alpine Fault in the next 50 years, which could cause horizontal movement of up to eight metres.

Researchers from Victoria University and GNS Science have said the Alpine Fault has moved more than any other known fault on land in the world.

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