Following on from the the 5.5 quake at 1pm today another large quake has just rocked Christchurch.

BREAKING NEWS: Another very powerful earthquake has just struck Christchurch, following a powerful magnitude 5.5 quake which rocked the city this afternoon.

GNS Science spokesman Kevin Fenaughty said the latest aftershock was “over six” in magnitude. ..”More on Stuff

Update:

The following day GNS upgraded the quake to a 6.3, the same size as that which hit Christchurch on 22 February..

Last month GNS officials cautioned that Canterbury has a nearly one-in-four chance of a third major earthquake of up to magnitude 7.0 during the next year. The devastating quake on  22 February 2011 was a magnitude  6.3.

Update:

Within hours Prime Minister John Key confirmed that the quake measured 8 on the Mercalli Scale, i.e. “Severe Shaking.”  The devastating earthquake in February was a Mercalli Scale 9.

“The June 13, 2011 South Island, New Zealand earthquake is a continuing part of the earthquake sequence that initiated with the magnitude 7.0 September 3, 2010 Darfield, New Zealand earthquake. The June 13, magnitude 6.0 earthquake is a dominantly strike-slip faulting earthquake that is at the eastern end of the inferred rupture of the 21 February 2011 magnitude 6.1 earthquake. Both this magnitude 6.0 event and the previous magnitude 6.1 event have an inferred fault plane striking approximately east-northeast. The entire earthquake sequence is broadly associated with regional plate boundary deformation as the Pacific and Australia plates interact in the central South Island, New Zealand.

This latest earthquake, similar to the February 21 earthquake, is close to the main population centers of Christchurch, New Zealand. This region has suffered substantial casualties and damage to buildings, infrastructure, and lifelines from a series of events starting with the February 21 earthquake. Additionally, the earthquakes close to Christchurch caused substantial liquefaction in residential areas. The June 13 earthquake was preceded by a nearby magnitude 5.2 foreshock, about 1 hour and 20 minutes earlier. There is no specific surface fault that has been observed for the post-September 3 earthquakes near Christchurch, or directly linking them to the observed September surface fault rupture. There have however been a substantial number of aftershocks forming a continuous swath extending from the September 3 events to the June 13 earthquake.” source

Our thoughts are with the people of Christchurch on what is going to be a very difficult day.