The Canterbury earthquakes are the "best-case scenario" for how such a disaster plays out in a coastal New Zealand city, a scientist says.
University of Canterbury coastal scientist Deirdre Hart today told the Australasian natural-hazards conference that Christchurch's geography made it better placed than other New Zealand cities to cope with a major quake.
"At least in Christchurch we had parts of the city that were not coastal. We had inland parts. I'd suggest it is New Zealand's best-case scenario,'' she said.
"If what we've observed here happens to other cities like Auckland, Wellington or Dunedin, the impact would be a lot greater because with the coasts and the rivers, there's a lot less space between them and the city."
Wellington was especially vulnerable, she said.
"I think the waterfront and the CBD, the reclaimed areas, are very much at risk,'' she said.
"Wellington is incredibly vulnerable in terms of its lifelines. [The Eastbourne] road would crack and fall into the sea. The Hutt Hospital would be cut off.
"The emergency response people already have problems with in a bad storm in Wellington. Add that to when the roads are falling into the sea and crumbling buildings having bits falling off ... I think I'll stay here."
Hart told the conference that coastal and river impacts from quakes needed equal standing with seismic and engineering factors.
About 6500 years ago, Christchurch's coastline was much further west, cutting through Riccarton to the base of the Port Hills, and much of the city was built on ancient sea deposits of silt and sand.
As a result, coastal and riverside areas had extremely vulnerable infrastructure, Hart said.
"When you put infrastructure into coastal and river areas, it's harder to put down a nice, neat grid network,'' she said.
"By putting down roads with pipes and holes underneath and having this inbuilt infrastructure in the deposits, you're magnifying the hazards.
''A lot of the liquefaction that we've seen coming up through roading systems, the recent rainfall, the potholing we've seen, is a product of cracks that appeared in pipes during the earthquakes."
The conference will run until Friday.