Smaller chances of another large Canterbury aftershock

The chances of another big aftershock hitting Christchurch are slowly falling. Photo / Mark Mitchell -

New data shows a steady decline in the chances of another large aftershock striking Canterbury in the next year.

GNS Science data for the year to come projects a four per cent chance of a magnitude 6.5 to 6.9 quake - down from five per cent last month.

The probability of a magnitude 5.0 to 5.4 aftershock dropped from 82 to 78 per cent, while the chance of a 5.5 to 5.9 magnitude shock went down two per cent to 37 per cent.

However, the probability of a magnitude 6 to 6.4 quake remained unchanged at 10 per cent.

The chances of a magnitude 7 or more shock striking the region remained static at two per cent.

The zone covered by the figures extends from Hororata in the west to large parts of Banks Peninsula, and from Kaiapoi in the North to Lincoln in the south.

With every month that passes without a major aftershock probabilities will continue falling, a GNS Science statement said.

"However, if another large aftershock occurs it can re-energise the system and spark a resurgence of earthquake activity for a month or so."

- HERALD ONLINE