The largest aftershock, on Oct. 4, measured 5.3 instead of 5.5, she said.

The largest aftershock was measured at 5.2 and struck at 1.52 pm.

It was the sixth largest aftershock since the magnitude 7.1 shake in September 2010.

Several large aftershocks were felt in the general area, described as a low rumble followed by a loud bang.

A large aftershock of magnitude 6.3 occurred on 22 February 2011 at 12:51 pm.

The two largest aftershocks measured 6.0 and 6.1 M.

Three large aftershocks occurred several weeks after the main event.

The two large aftershocks at 12:55 and 13:02 could also be felt in Austria.

There have been at least nine large aftershocks in total.

On 13 June 2011 Christchurch was again rocked by two more large aftershocks.