Scientists studying the faultline that runs along the Southern Alps have gone back thousands of years further than previous studies and discovered it is "well behaved" and something of a creature of habit.
But they warn the new information leads them to believe there is a 30 per cent chance of a destructive magnitude 8 earthquake within the next 50 years.
Scientists had previously only known the ages for four large Alpine Fault quakes dating back to about 1000AD.
In Science magazine this week, GNS Science, with help from Victoria University of Wellington, as well as scientists from Italy, Israel, and the US, revealed the fruits of their four-year research project.
Focussed on a remote river terrace near Milford Sound, they used radiocarbon dating of seeds, leaves, and reeds contained in swampy sediments, to determine the ages of 24 surface ruptures, of about magnitude 8, dating back to 6000BC.
The findings dramatically improve the known earthquake history of the 600km-long fault which runs up the spine of the South Island.
The mean interval between large earthquakes on the fault is 330 years and two thirds of the intervals were between 260 and 400 years. The fault last ruptured in 1717.
"On a national scale, we can now base our modelling on knowledge of the timing of 24 earthquakes compared to the four that were known prior to this investigation," said project co-leader Kelvin Berryman, of GNS Science.
"This will greatly improve the reliability of earthquake hazard modelling."
University of Otago geologist Richard Norris said a magnitude 8 quake could cause widespread damage in Westland, landslides and damage in places like Queenstown, Te Anau, Wanaka and Mt Cook.
In Christchurch and Dunedin the intensities will be lower but could damage poorly constructed buildings and possibly cause some liquefaction.
Places such as Nelson, Wellington and Invercargill could also expect to feel some shaking.
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