Wellington’s disaster planners are preparing for the possibility that a major earthquake will fracture the region so severely it effectively splits into seven “islands”.
The fear is that a rupture of magnitude 7.5 or greater along the Wellington Fault will damage road and water links in the capital so badly that its northern and western suburbs are cut off from its central, eastern and southern suburbs. They could remain cut off by road for up to 10 weeks.
Not only that, but Wellington’s two halves would join Tawa-Porirua, Kapiti, Lower Hutt, Upper Hutt and Wairarapa in being separated from each other when it comes to roads, water supply, power and access to medical care.
The seven “islands” would not be separated by water, but would be cut off from each other by crumbled infrastructure. In some cases, main roads could be out of action for four months.
It is for this reason that Capital and Coast District Health Board (CCDHB) has stored water, fuel and emergency supplies at locations across the region, so the so-called islands can be self-sufficient.
Health board members were briefed this week on the complexities of responding to a devastating earthquake.
Up to 150 people could lose their lives, while another 750 could be seriously injured and 11,000 could sustain minor injuries.
Board members were told medical staff would be overwhelmed and probably have to work from remote locations, such as carparks. Some staff may suffer injuries themselves in the quake.
CCDHB acting chief operating officer Carey Virtue said the bleak scenario had been known for some time, but the “seven islands” terminology was born from Civil Defence in the wake of November’s 7.8 magnitude Kaikoura earthquake.
“We anticipate that a seven island scenario would result in enormous disruption to the region’s infrastructure and, therefore, delivery of our usual health services.”
Wellington Region Emergency Management Office regional manager Bruce Pepperell said the contingency plan was for food, clean water and vital medical supplies to be delivered by air and sea.
That meant relying on Wellington’s port, which was damaged in the Kaikoura quake, to hold up. Failing that, ships with their own cranes would be brought in.
Many roads, such as the Centennial Highway – SH1 from Wellington to Paekakariki – would be completely inaccessible in the event of an adjacent cliff falling.
But construction of the planned Transmission Gully motorway and Petone-Grenada highway would provide more flexibility, Pepperell said.
“There’s no doubt it would be a sizeable challenge, but it’s not something the region would deal with alone.”
The Wellington Fault last ruptured between 170 and 370 years ago, and there is a 10 per cent chance it will rupture again within the next century, according to GNS Science.
IF THE BIG ONE HITS WELLINGTON
Roads: State Highways 1 and 2 – the only two main highways in and out of Wellington – would be knocked out for 120 days along with the region’s linking roads – Akatarawa Rd, Paekakariki Hill Road and SH58 – and the region’s rail lines.
Utilities: Most of the region would be without gas for nearly three months, without wastewater systems for potentially as long, without power and water for anywhere between three weeks and two months, and without phones for 10 days.
Water: 100,000 people in Wellington city could face up to 20 days without access to water. GNS Science has said stored water could run out weeks or months before supply can be restored to the central city and outlying suburbs.
Source: Wellington Lifelines Group report 2012 and GNS Science report 2013