Between 15,000 and 25,000 buildings believed to be at risk of collapse in a moderate earthquake.
The Alpine fault, the most likely source of a catastrophic New Zealand earthquake, has a 6 to 9 per cent chance of rupturing in the next 20 years.
The Wellington Fault, which runs under the city's CBD, produces a large earthquake every 500 to 1000 years.
Since 1843, 483 people have died in quakes.
Unreinforced masonry buildings resulted in the death of 39 people in the February 22, 2011 earthquake in Christchurch.
