Aftershocks in Canterbury are decreasing, but GNS Science says there is still a possibility of a magnitude 6.0 or above to hit the region.
The agency has issued updated figures, based on a new forecasting model.
It says there is a 15% chance a magnitude 6.0 - 6.4 to aftershock will hit in the next year.
But just a 4% chance of a quake measuring magnitude 6.5 - 6.9.
Anything above that is very unlikely with only a 1% chance of a quake measuring more than magnitude 7.0.
GNS forecasting also shows the probability of magnitude 5.0 aftershocks is still quite high, (88% for 5.0 - 5.4 and 46% for 5.5 - 5.9) and there will likely be several per year over the next few years.
The aftershock zone encompasses Christchurch city, Banks Peninsula, and west to Hororata, north to Kaiapoi and south to Lincoln.