Scientists think there's a 30 percent chance the South Island's Alpine Fault will generate a large earthquake in the next 50 years.
It comes from a new geological study of the fault by GNS Science, spanning activity over the past 8000 years.
In earthquake terms, scientists have found the fault is remarkably consistent, rupturing on average each 330 years. The last major quake occurred 295 years ago.
When the fault does rupture, it produces an earthquake of about a magnitude 8.0.
Scientists used a range of investigation techniques, including radiocarbon dating of seeds, leaves, and reeds contained in swampy sediments, to determine the ages of the ruptures.The project has produced one of the longest continuous earthquake records of any on-land plate boundary fault in the world. Knowing the ages of so many major earthquakes enables a better understanding of the fault's behaviour.
"There is considerable interest in these new results given that earthquakes on the Alpine Fault pose a threat to large parts of the South Island," said project co-leader Kelvin Berryman of GNS Science.
"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. This will greatly improve the reliability of earthquake hazard modelling," Dr Berryman said.
Release / RBG News