"I think there will be lots of aftershocks around Christchurch for about a year, But they won't be as big as the latest one. They are likely to get smaller and less frequent", said Kevin McCue, director Australian Seismological Centre.
He said: "The biggest surprise about Tuesday's 6.3-magnitude aftershock in Christchurch was that it took so long after a powerful quake last Sep, which caused no fatalities but weakened many buildings. I expected it within the first four or five days."
According to News.com.au website, some Australian and New Zealand seismologists are in dispute over whether this earthquake is related to the Sep aftershock or not.
Australia seismologist Dr Trevor Allen said that Christchurch earthquake happened in a different fault line.
He added: "We say that if it happens on a different fault line or a different section of the same fault line, then it is its own earthquake."
A New Zealand geologist Kelvin Berryman said that the strength of the deadly earthquake on Tuesday might have been magnified as it reflected off hard volcanic rock below its epicentre.