GNS Science says the chance of a magnitude 6.0 to 6.9 earthquake in Canterbury within 12 months has gone up to 30% since Monday's earthquakes.
Vulcanologist Gill Jolly told Morning Report that before Monday, the likelihood of a large quake was expected to be 25%.
Dr Jolly said that more aftershocks on Wednesday morning of magnitude 5.0 and 4.2 are within the expected range following Monday's large quakes and appear to be on the same faultline as the earthquake on February.
