An aftershock struck Christchurch on Sunday night, with reports it was strong enough to knock items from shelves.
The 5.1 magnitude aftershock struck at 9.47pm, and was at a depth of 10 kilometres. One of the strongest aftershocks since the 22 February quake, it was centred 10 kilometres east of the city.
Civil Defence says a quick inspection by authorities of buildings in the inner city has shown that some loose masonry has fallen. A dairy towards the east of Christchurch was damaged.
Christchurch mayor Bob Parker says in the eastern suburbs where the quake was centred, the reports were of a violent shake.
"Our thoughts are with the folk who've just had, to put it bluntly, a gutsful of nights of trauma - and here's another one."
Mr Parker says teams were checking for damage.
GNS seismologist Caroline Ashenden says the aftershocks are part of the normal sequence following the 7.1 earthquake on 4 September 2010.
Later, a 2.9 quake was recorded at 10.05pm and a 3.2 tremor at 1.22am on Monday, both 10 kilometres east of the city.
