3 Apr 2012

Big quakes at longer intervals than thought

9:01 pm on 3 April 2012

Scientists have discovered that major earthquakes in the South Island have occurred at longer intervals than first thought.

A recent study by GNS scientists, Otago University's geology department and American researchers has found ruptures along the Alpine Fault seem to have occurred between 450 and 480 years apart.

The research looks at the last three major earthquakes that occurred as far back as 750 AD.

GNS scientist Kelvin Berryman says while the cycle of large quakes is longer than scientists originally believed to be, there is still no way of knowing when the next might be.

"We could be ... a hundred years or more away if this 480-year cycle continues into the next one, or it could be back into the average of 300 years, and of course it could be tomorrow."

Dr Berryman says it would be unwise and unsafe for people to relax preparations for a major earthquake.

Major quakes are those at between magnitude 7 and 8.