Higher risk of Alpine Fault quake highlights need for preparation on West Coast
Tuesday, 20 April 2021
The West Coast is one of the regions most at risk if a massive earthquake is generated by the Alpine Fault, but local leadership say the region is prepared.
New research has shown the chances of the South Island’s Alpine Fault generating a damaging earthquake in the next 50 years are much higher than previously thought.
The research, led by Te Herenga Waka-Victoria University of Wellington senior lecturer Dr Jamie Howarth, showed the probability of that earthquake occurring before 2068 is about 75 per cent. It had previously been thought to be about 30 per cent.
Scientists from Victoria University, the University of Otago, GNS Science, the University of California, and the United States Geological Survey also calculated there was an 82 per cent chance the earthquake would be of magnitude-8 or higher.
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Westland mayor Bruce Smith said while the latest research was no cause for panic, it underscored the need for the district to increase its investment into preparation.
The Alpine Fault is about 600 kilometres long and runs between Milford Sound and Marlborough, and diagonally through Franz Josef township. The fault has ruptured five times in the past 1100 years, each time producing an earthquake of magnitude 7 to 8.
The fault line poses one of the biggest natural threats to New Zealand – particularly the West Coast, Canterbury and Otago.
“We all know we live next to the Alpine Fault line, and we’ve known it for a long time,” Smith said.
“The question of timing has always been pretty fluid, but this latest report indicates the probability has shifted significantly and from a Civil Defence point of view, that is concerning.”
Smith said the Westland District Council was already preparing the region for the worst, such as getting basic satellite communication systems in place, managing its lifeline assets along the coast, and accelerating the need for fuel storage in the Grey and Buller districts.
“The focus is certainly there, but … we still need the funding to be able to [sufficiently prepare].”
Smith said it was not realistic to expect Westland ratepayers to carry the brunt of the funding needed.
“A really focused response in government funding is necessary to enable practical things to be done on the ground with some urgency.”
West Coast District Health Board deputy chairman and former Grey mayor Tony Kokshoorn was confident the West Coast was prepared for when disaster struck.
Kokshoorn said it was inevitable that a magnitude 8-earthquake would mean major disruption and damage to the region – experts expected one third of the region’s bridges would be destroyed by an Alpine Fault quake and many communities could be isolated for weeks.
But the region was in “as good a position as any” to deal with it, he said.
Kokshoorn referred to the Westland Recreation Centre in Greymouth that had been erected with an importance level four earthquake rating – the highest possible – so it could be used immediately after an earthquake struck.
The stadium was international-grade and had two indoor full-size courts that could be turned into a field hospital.
Grey district mayor Tania Gibson had previously said the council would be happy to open the stadium doors when needed. It could be used as a welfare centre or as a medical centre where people could be treated.
Kokshoorn said ignoring the informed advice of scientists was detrimental, but there was no reason for alarm.
“Forewarned is forearmed. These are estimates. We have to take them seriously, but at the same time we have to be realistic too.
“Life has to go on while we make sure we are as prepared as we can possibly be.”